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Glossary
 
  • Abrasive
     

    1. Small, hard, sharp cornered, fragments of natural or synthetic material that will scratch or wear another material.

    2. A substance used to smooth or polish a surface by grinding or scrapping.

     
         
  • ABS
     

    Antilock braking system.

     
         
  • ABS override
     

    Switch for the driver to turn off the ABS system when on soft surfaces (like sand or deep gravel) where locking the wheels would be an advantage.

     
         
  • Accelerator
     

    1. A device for increasing the speed of a motor vehicle engine. 2. A foot-operated throttle that varies the supply of fuel-air mixture to the combustion chamber. 3. Pedal operated by the driver s right foot that controls the flow of air into the engine.

     
         
  • Accelerator pump
     

    Part of the carburetor. A small pump that enriches the fuel-air mixture during acceleration.

     
         
  • Aftermarket
     

    Vehicle accessories that are not fitted by the manufacturer.

     
         
  • Aftermarket Parts
     

    New parts that replace damaged parts. They may be a generic part.

     
         
  • Airbag
     

    A secondary safety restraint which will inflate in 25 milliseconds in serious front collisions to protect the passengers and driver.

     
         
  • Air cooled engine
     

    An engine which is cooled directly by ambient air, where the cooling air passes directly over fins on the cylinders and cylinder hood, without the need for a water jacket and radiator.

     
         
  • Air filter
     

    A device on the engine air intake that prevents dust and dirt entering the engine.

     
         
  • Airflow
     

    The passage of air over a moving vehicle.

     
         
  • Air-fuel Mixture
     

    The air and fuel mixture mixed by the carburetor or fuel injection system and vaporized.

     
         
  • Air Jack
     

    A device for lifting a car.

     
         
  • Alignment
     

    The angles at which each wheel should be adjusted to maintain the specifications engineered by the vehicle manufacturer for the best performance of both the steering and suspension.

     
         
  • Alternator
     

    An electrical generator that mechanical energy into electrical energy for powering circuits in a vehicle. With the engine running, the alternator recharges the battery. The alternator provides as well all the electrical power needed to run the headlights, radio, air conditioner etc.

     
         
  • Antifreeze
     

    A liquid added to the water in the cooling system of a vehicle to lower its freezing point, raise the boiling point as well as prevent corrosion.

     
         
  • Antilock Brakes
     

    A computerized control system designed to prevent wheels from locking during hard braking; thereby allowing some steering control during an emergency.

     
         
  • ARA
     

    Automotive Recyclers Association. A non-profit trade association representing an industry dedicated to the efficient removal and reuse of automotive parts and the safe disposal of inoperable motor vehicles

     
         
  • Automotive Recycling
     

    The efficient, ecological disposal of inoperable motor vehicles and reclaiming reusable parts and components

     
         
  • Automotive Recyclers Association
     

    An international trade association which has a represented an industry dedicated to the efficient removal and reuse of automotive parts, and the safe disposal of inoperable motor vehicles.

     
         
  • Automotive Recycler
     

    A professional who purchases vehicles for re-use. Dismantles vehicles, collects and disposes of fluids in an environmentally responsible fashion, tests salvageable parts, classifies and prices them for sale and disposes of remaining vehicle hulk

     
         
  • Automatic Transmission
     

    A computer system which decides when the transmission should shift and then delivers an electrical signal to create that shift. Power is transferred from the engine using a fluid coupling called a torque converter.

     
         
  • Axle
     

    A metal shaft that transfers torque from the differential to the wheels.

     
         
  • ABS
     

    Abbreviation for Anti-Lock Braking System.

     
         
  • ABS Pressure Switch
     

    Sensor that monitors hydraulic system pressure and controls pump motor in an ABS application.

     
         
  • AC
     

    Alternating current.

     
         
  • Acceleration Sensor
     

    Provides acceleration data to computer in electronic shock absorber system.

     
         
  • Accelerator Pump
     

    Device to force a fuel stream into air horn as needed.

     
         
  • Accessory Systems
     

    Those that increase comfort or are a convenience for vehicle occupants, such as air conditioning or power windows, and a window defogger.

     
         
  • Accumulator
     

    Air conditioning system component that removes moisture and stores extra refrigerant.

     
         
  • AC Generator
     

    Device that produces alternating current; an alternator.

     
         
  • Active Sensor
     

    One that generates its own voltage signal in response to a change in a condition.

     
         
  • Active Suspension System
     

    A method of ride control using hydraulic rams, rather than conventional shock absorbers and springs.

     
         
  • Actuator
     

    Device that performs an action or outputs a signal in response to a signal from a computer.

     
         
  • Adhesive
     

    Substance used to chemically and mechanically bond two materials together

     
         
  • Adjustable Rocker Arm
     

    Used with mechanical lifters; permits changing valve train clearance.

     
         
  • Air Blowgun
     

    Tool used to blow off bits of dirt, solvent, or other debris from parts.

     
         
  • Air Chisel
     

    A cutting tool powered by compressed air that is used to remove faulty exhaust system parts.

     
         
  • Air Cleaner Carbon Element
     

    A canister of carbon granules that absorbs fuel vapors when engine is shut off.

     
         
  • Air Compressor
     

    A pump that forces air, under pressure, into a storage tank.

     
         
  • Air Cooling system
     

    The use of cooling fins and air movement to dissipate heat from the engine.

     
         
  • Airflow Sensor
     

    Device to monitor flow of outside air into engine.

     
         
  • Air Horn
     

    Part of the carburetor that channels air into the intake manifold.

     
         
  • Air Injection System
     

    A method of reducing HC and CO emissions by forcing fresh air into the exhaust ports of the engine.

     
         
  • Air Jet Chamber
     

    One that uses an injected stream of air for improved fuel mixing and combustion.

     
         
  • Air Pollution
     

    Release of harmful substances into the air due to engine operation and similar causes.

     
         
  • Air Pump
     

    Belt-driven pump that provides input for the air injection system.

     
         
  • Air Shocks
     

    Shock absorbers that use air pressure, rather than springs, to maintain vehicle height.

     
         
  • Air Spring
     

    Air-filled rubber cylinder that is lighter than the equivalent coil spring.

     
         
  • Air Tests
     

    The use of air pressure to diagnose automatic transmission problems.

     
         
  • Air Tool
     

    A tool powered by compressed air.

     
         
  • ALDL
     

    Assembly line diagnostic link, also called the diagnostic connector.

     
         
  • Alignment Rack
     

    Fixture onto which the vehicle is driven for alignment measurement and adjustment activities.

     
         
  • Alternate Engine
     

    Engine types other than traditional internal combustion, four-stoke-cycle, piston engine.

     
         
  • Alternate Fuel
     

    Fuels other than gasoline and diesel fuel.

     
         
  • Alternator
     

    An AC generator.

     
         
  • Alternator Bearings
     

    Needle or ball-type bearings used 10 provide a low-friction surface for a rotor.

     
         
  • Altitude Compensator
     

    A system that changes the air-fuel ratio as the vehicle moves to higher or lower elevations.

     
         
  • AM
     

    Amplitude modulation (type of radio broadcasting).

     
         
  • Ambient Temperature Switch
     

    One that prevents air conditioner operation when outdoor temperatures are below a set point.

     
         
  • Amplifier
     

    Electronic circuit that uses a small current to control a much larger current.

     
         
  • Amplify
     

    To increase in strength or volume.

     
         
  • Anaerobic Sealer
     

    A sealer that cures in the absence or air.

     
         
  • Analog
     

    A signal that can vary continuously in value.

     
         
  • Analog Signal
     

    One that continually changes strength. Analog voltmeter code Trouble code read by counting the number of needle deflections on a meter.

     
         
  • Antenna Trimmer
     

    Adjustment screw on a radio, used to obtain best reception.

     
         
  • Antifreeze
     

    Liquid used in a cooling system that is mixed with water and prevents the water from freezing. The solution serves as the engine coolant.

     
         
  • Antifreeze Strength
     

    Measurement of concentration of coolant solution.

     
         
  • Antifriction Bearing
     

    Bearing that uses balls or rollers to decrease friction.

     
         
  • Anti-Lock Brake Computer
     

    ECM that accepts wheel sensor inputs and controls braking of the vehicle.

     
         
  • Anti-Lock Brakes
     

    Computer-controlled brakes that will not "lock" and permit wheels to skid.

     
         
  • Anti-Rattle Clips
     

    Metal components designed to keep brake pads from vibrating and rattling.

     
         
  • Anti-Skid System
     

    Another name for anti-lock braking system.

     
         
  • Apprentice Mechanic
     

    A beginner who is learning under direction of an experienced auto technician.

     
         
  • Armature
     

    Rotating support for multiple windings in a motor.

     
         
  • Asbestos
     

    A mineral material once widely used on clutches and brake linings. Asbestos dust is a known cancer-causing agent.

     
         
  • Asbestos Lining
     

    Anti-friction material once widely used for brake linings.

     
         
  • ASE
     

    Abbreviation for National Institute for Automotive Service Excellence, which certifies auto technicians.

     
         
  • Aspect Ratio
     

    The relationship of tire height to width, or profile.

     
         
  • Asphyxiation
     

    Death resulting From lack of oxygen to breathe.

     
         
  • Atmospheric Pressure
     

    The pressure exerted by the Earth's atmosphere (14.7 psi at sea level).

     
         
  • Automatic Clutch Adjuster
     

    A mechanism designed to automatically remove any play from a clutch cable system.

     
         
  • Automatic Temperature Control System
     

    A method of climate control using sensors and a computer to maintain a preset temperature in the vehicle's passenger compartment.

     
         
  • Automatic Transmission
     

    One that does not have to be shifted manually.

     
         
  • Automatic Transmission Electronic Controls
     

    Computerized selection of shift points, based on input from sensors.

     
         
  • Automatic Transmission Fluid
     

    Oil with special additives to make it compatible with Friction clutches arid bands.

     
         
  • Automatic Transmission Slippage
     

    Condition in which engine races as transmission shifts (in severe cases, the car may not move at all).

     
         
  • Automotive Clutch
     

    A mechanical device used to connect and disconnect a manual I transmission from engine power.

     
         
  • Auto Technician's Certification
     

    A program in which technicians take written tests to become certified by the National Institute for Automotive Service Excellence (ASE).

     
         
  • Auxiliary Chain
     

    A chain and sprocket combination used to drive engine auxiliaries, such as the oil pump.

     
         
  • Axle C-clip
     

    Spring steel retainer that fits in a groove on the axle end.

     
         
  • Axle End Play
     

    In-and-out movement OF the axle, adjusted to specification by using shims.

     
         
  • Axle Retainer Plate
     

    See axle shaft retainer.

     
         
  • Axle Shaft Retainer
     

    Devices that attach to the outside of an axle housing to prevent axles from sliding out.

     
         
  • Axle Shims
     

    Used between axle housing and retainer to limit end play of the axle.

     
         
  • Battery
     

    Storage device for electrical power. In a vehicle this lead acid secondary cell stores chemical energy which can then be released as electrical power.

     
         
  • Battery Acid
     

    A liquid mixture of 40% to 60% sulphuric acid and 60% water to form an efficient electrolyte.

     
         
  • Battery Cable
     

    Heavy cable that provides power from the battery to the rest of the car.

     
         
  • Battery Charger
     

    An electrical device used to recharge a vehicle battery from mains power.

     
         
  • Battery Terminal
     

    The exposed ends of a battery that provide voltage when connected to a circuit; soft metal projection on the battery to which the electrical cable is clamped.

     
         
  • Ball Joint
     

    A ball-and-socket joint giving good flexibility within a range of motion. Allows the suspension to move up and down while still being able to turn the wheels.

     
         
  • Black Smoke
     

    Smoke from the tailpipe caused typically when the air-fuel ratio mixture is too high. The fuel is not fully burned and soot results.

     
         
  • Blindspot
     

    An area behind and to either side of the drive which he cannot see when facing straight ahead.

     
         
  • Brake
     

    A device that creates friction to a surface to slow it, stop it, or hold it stationary; a device that slows or stops the rotation of the wheels, so tire friction slows or stops a vehicle.

     
         
  • Braking Distance
     

    The distance for a moving vehicle to stop on a clean dry surface, not including any mechanical failures, perception problems of the driver, reaction time. The distance needed is increased with speed, poor road surface or any other non-ideal conditions.

     
         
  • Backfiring
     

    Condition caused by air-fuel mixture igniting in the intake manifold or exhaust system.

     
         
  • Backing Plate
     

    Component that holds the shoes, wheel cylinder, and other parts inside a drum brake.

     
         
  • Back Pressure
     

    Pressure developed in the exhaust system when the engine is running.

     
         
  • Backup Light Switch
     

    An electrical switch that completes a circuit to the back up lights whenever the reverse gear if engaged.

     
         
  • Bad Hydraulic Lifter
     

    A cause of valve clatter.

     
         
  • Balancer Shaft
     

    A Rotating component used in some engines to cancel vibration produced by another rotating shaft such as the crankshaft.

     
         
  • Ball and Trunnion U-joint
     

    A seldom-used type of constant velocity U-joint.

     
         
  • Ball Joint
     

    Swivel joint that provides free movement for steering knuckle and control arm.

     
         
  • Ball Joint Balloon Seal
     

    An airtight seal used to protect the ball joint.

     
         
  • Ball Joint Wear Indicator
     

    An indicator on the shoulder of the ball joint that shows the amount of wear.

     
         
  • Ball Nut
     

    Component that rides up and down a worm gear as the worm rotates in a recirculating ball gearbox.

     
         
  • Ball Sockets
     

    Components that allow motion in up-and-down and side-to-side direction.

     
         
  • Band
     

    A metal strap with a frictional material lining that can clamp a clutch drum in an automatic transmission to stop its rotation.

     
         
  • Band Adjustment
     

    Check and adjusting the tightness of automatic transmission band for proper automatic transmission shifting and driving conditions.

     
         
  • Bare Cylinder Head
     

    A head with all of its components removed including valves, springs, seals, etc.

     
         
  • Barrel
     

    A cylinder.

     
         
  • Basic Circuit Problem
     

    One caused by something in the circuit itself that increases or decreases an electrical value.

     
         
  • Battery Activation
     

    To fill with electrolyte then charging a dry battery.

     
         
  • Battery Cables
     

    Heavy gauged wires connected to the battery. Typically two are used. One, connects the battery to the starter (positive) and the second from the battery to a grounding point on the vehicle.

     
         
  • Battery Charge Condition
     

    The state of its plates and electrolyte.

     
         
  • Battery Charger
     

    Device for restoring battery to a proper electrical charge.

     
         
  • Battery Drain Test
     

    A method of checking for unusual current draw with ignition key off.

     
         
  • Battery Leakage Test
     

    Check to determine if current is discharging across top of battery case.

     
         
  • Battery Load Test
     

    A test for battery capacity, made under full electrical load.

     
         
  • Battery Terminal Test
     

    A test for good contact between cables and terminals.

     
         
  • Battery Voltage
     

    For batteries used in modern cars, 12.6V; older cars, 6.3V.

     
         
  • Battery Voltage Test
     

    Check of battery charge with a voltmeter.

     
         
  • BDC
     

    Bottom Dead Center. The lowest position a piston can reach with in its cylinder.

     
         
  • Bearing Clearance
     

    Small space between moving parts, permitting oil to enter for lubrication.

     
         
  • Bearing Crush
     

    Slight oversize of bearings to jam them in place when cap is tightened on connecting rod.

     
         
  • Bearing Housing
     

    Section of the turbocharger housing containing the shaft bearings and oil seals.

     
         
  • Bearing Noise
     

    Constant whir or humming sound due to damage or wear of bearings in the carrier or axle assemblies.

     
         
  • Bearing Packer
     

    Tool used to simplify packing of grease into wheel bearings.

     
         
  • Bearing Spread
     

    Practice of making bearing halves slightly wider than necessary to hold them in place during installation.

     
         
  • Bell Housing
     

    The metal shell surrounding the clutch assembly that bolts to the rear of the engine.

     
         
  • Belted Bias Tire
     

    A bias-ply tire with extra belts added beneath the tread area.

     
         
  • Belts
     

    Fabric made of steel or other material that is placed between body plies and tread.

     
         
  • Belt Squeal
     

    Noise resulting from a slipping drive belt.

     
         
  • Bench Bleed
     

    Method of filling and hand-pumping a master cylinder before installation to remove trapped air.

     
         
  • Bent Push Rod
     

    A cause of valve clatter. Bent rods usually must be replaced.

     
         
  • Bhp
     

    Abbreviation for brake horsepower, a measurement of usable horsepower of an engine.

     
         
  • Bias Ply Tire
     

    One with plies running at an angle from bead to bead.

     
         
  • Bleeder Screw
     

    Fitting on top of brake caliper that allows air to be bled from system.

     
         
  • Bleeding
     

    Process of removing any trapped air from a hydraulic system.

     
         
  • Block Diagram
     

    A simple drawing, using rectangles and lines, that shows how sensors, computers, and actuators are interconnected.

     
         
  • Block Heater
     

    A heating device used to warm the block of a diesel engine in cold weather.

     
         
  • Block Line Boring
     

    A technique used to "true" misaligned main bearing bores.

     
         
  • Blow-By
     

    Oil vapors and other emissions that leak past piston rings into the crankcase.

     
         
  • Blower
     

    A fan that forces air to move tough the evaporator of an air conditioning system.

     
         
  • Blow Gun
     

    An air-powered device used for cleaning and drying parts washed in solvent, or blowing away accumulations of dust and dirt.

     
         
  • Blown Head Gasket
     

    Leak of compression from one or more cylinders results from failure of the gasket.

     
         
  • Blow-through Turbo
     

    A turbocharger located ahead of the compressor or throttle body. It compresses only air.

     
         
  • Body Lubrication
     

    Applying oil and grease to such friction points as hinges and latches.

     
         
  • Boiling a Block
     

    Cleaning technique in which strong solvents and heat are used to remove mineral deposits from the water jacket.

     
         
  • Bolt Size
     

    Measurement of the outside thread diameter.

     
         
  • Boost Pressure
     

    The additional amount of pressure supplied to the intake system produced by a turbocharger or blower.

     
         
  • Boot
     

    Flexible pleated covers placed over the CV joints of a front-wheel-drive vehicle to keep road dirt out of them.

     
         
  • Boot Deterioration
     

    Cracking, tearing, or other damage to a boot, which would allow road dirt and moisture to enter the CV-joint.

     
         
  • Bowl Vent
     

    Passageway that prevents a pressure buildup in fuel bowl.

     
         
  • Box End
     

    A wrench that has completely closed ends that surround and grip a bolt head.

     
         
  • Brake Booster
     

    Component operated by vacuum or power steering system to decrease braking effort needed.

     
         
  • Brake Lines
     

    Metal tubing and rubber hoses connecting master cylinder to wheel brake assemblies.

     
         
  • Brake Pads
     

    Replaceable friction surfaces mounted on caliper of disc brake system.

     
         
  • Brake Pedal Assembly
     

    Foot lever for operating brake system.

     
         
  • Brake Pedal Vibration
     

    Pulsing movement of brake pedal, usually caused by out-of-round brake drum or warped rotor.

     
         
  • Brake Sensor
     

    Provides braking data to computer in electronic shock absorber system.

     
         
  • Brake Shoes
     

    Curved, replaceable friction surfaces used with drum-type brakes.

     
         
  • Brake System
     

    Components that are used to stop a vehicle.

     
         
  • Brake System Flushing
     

    Removal of all old fluid by pressure bleeding, then replacing it with fresh fluid.

     
         
  • Brake Warning Light
     

    Dashboard indicator that warns of low brake system hydraulic pressure.

     
         
  • Braking Ratio
     

    Comparison of front wheel to rear wheel braking effort.

     
         
  • Break-Away Torque
     

    In a limited-slip differential, the amount of torque needed to make one axle rotate the clutches.

     
         
  • Brushes
     

    Sliding electrical contacts that ride on the slip rings of a generator.

     
         
  • BTU
     

    British thermal units; the units used to measure heat transfer.

     
         
  • Bubbling Sight Glass
     

    A sign that the air conditioning system is low on refrigerant and that air may be present.

     
         
  • Burned Fluid
     

    Condition caused by overheating due to slippage of transmission bands.

     
         
  • Burned Piston
     

    Actual melting or breakage of a part of the piston, resulting in a hole.

     
         
  • Burned Valve
     

    Valve face damaged by heat, allowing leakage of air-fuel mixture from cylinder during compression.

     
         
  • Bus
     

    A pathway for data inside a computer.

     
         
  • Bypass Lubrication System
     

    One that filters only some of the oil going to bearings.

     
         
  • Bypass Valve
     

    Method used to permit coolant circulation in engine when thermostat is closed.

     
         
  • Caliper
     

    Part of the braking system the holds and operates the brake pads; presses disk brake pads against brake rotor to provide friction to stop the wheel.

     
         
  • Cam
     

    A rotating lobe that changes regular circular motion into an irregular circular motion or into a back and forth motion.

     
         
  • Camshaft
     

    A shaft having a series of cams at intervals along its length, for operating the engine valve mechanism. Made up of a series of egg-shaped sections, which as they rotate raise and lower part of the valve train, which in turn causes the valves to open and close.

     
         
  • Capacitor
     

    A device for receiving and storing a charge of electricity; condenser.

     
         
  • CAR
     

    Certified Automotive Recycler. A designation awarded by ARA to recyclers who meet a set

     
         
  • Carbon Monoxide CO
     

    extremely poisonous gas which is potentially lethal. Created during combustion of fuel and is the result of incomplete combustion due to lack of oxygen.

     
         
  • Carburetor
     

    A device that vaporizes fuel and mixes it with air in an exact ratio and rate before it is supplied to the intake manifold. A meter that controls engine rpm and fuel mixture.

     
         
  • Catalytic Converter
     

    Exhaust emissions device that breaks down harmful exhaust emissions into carbon dioxide nitrogen and water by use of catalysts.

     
         
  • Chassis
     

    Frame of a car, which the body, engine, suspension, transmission of a vehicle are fastened.

     
         
  • Choke
     

    A valve at the top of the carburetor designed to richen mixtures for easier starting in colder weather.

     
         
  • Clutch
     

    A device in a machine for transmitting motion or for disconnecting related moving parts.

     
         
  • Combustion Chamber
     

    The area in the cylinder where the air/fuel mixture actually ignites and burns. Located between the top of the piston and the cylinder head.

     
         
  • Coolant
     

    Liquid designed to remove surplus heat from the engine. Coolant lowers the freezing point and raises the boiling point as well as prevents corrosion.

     
         
  • Cooling Fan
     

    A fan that pulls air past the radiator to keep the engine from overheating at low vehicle speeds.

     
         
  • Crankshaft
     

    A series of offset levers that connect to the pistons through connecting rods. As the pistons move, they turn the crankshaft, which turns the combustion into torque to drive the car.

     
         
  • Cylinder
     

    A round chamber for the piston to travel through.

     
         
  • Cylinder Head
     

    A casting forming part of the combustion chamber; housing for the valves, sparkplugs and injectors and carries part of the cooling system.

     
         
  • Cylinder Head Gasket
     

    Gasket located between the cylinders and the cylinder head to prevent leaks of compression and coolant.

     
         
  • Calibration Fluid
     

    A fluid that is less flammable than diesel fuel, used when testing injectors out of the engine.

     
         
  • Caliper
     

    The component that houses disc brake pads on both sides of the brake rotor and are forced together through applied brake fluid pressure to stop the rotor from turning, thus stopping the car. It is also the name of a tool to measure small inside and outside diameters.

     
         
  • Camber
     

    The inward or outward tilt of a wheel assembly.

     
         
  • Cam Ground Piston
     

    One that is ground slightly out of round to compensate for different rates of expansion.

     
         
  • Cam Lobe Wear
     

    Reduces valve lift, causing reduced engine power and rough idle.

     
         
  • Camshaft
     

    Rotating shaft with lobes that open valves at the correct times for proper engine operation.

     
         
  • Camshaft Drive
     

    Gears, a chain and sprockets, or a belt and sprockets that run the camshaft at half the speed of crankshaft rotation.

     
         
  • Camshaft Lift
     

    Amount of valve train movement produced by the cam lobe.

     
         
  • Cam Thrust Plate
     

    Component that limits front-to-rear movement of camshaft.

     
         
  • Cap Pressure Rating
     

    Pressure at which the cap valve opens to vent coolant to the overflow tube or recovery tank.

     
         
  • Caps
     

    Covers over cell openings on top of a battery.

     
         
  • Carbon Trace
     

    Small line of conductive carbon-like material on a distributor cap or rotor.

     
         
  • Carburetor Cleaner
     

    A chemical used to dissolve gums and material from carburetor parts.

     
         
  • Carburetor Flooding
     

    Excess fuel flow, preventing starting of engine.

     
         
  • Carburetor Fuel System
     

    One that mixes air and fuel and directs it to engine cylinders through an intake manifold.

     
         
  • Carburetor Kit
     

    Gaskets, needle valves, and other parts needed to rebuild a carburetor.

     
         
  • Carburetor Rebuild
     

    Overhaul, with cleaning and part replacement.

     
         
  • Carburetor System
     

    Network of passages that control the air-fuel ratio under specific engine conditions.

     
         
  • Cartridge Oil Filter
     

    One with a replaceable filter element.

     
         
  • Case
     

    The outer protective shell of a battery, or any other component or device.

     
         
  • Case Bearing Preload
     

    Amount of force pushing differential case bearings together.

     
         
  • Caster
     

    Forward or backward tilt of steering knuckle.

     
         
  • Caster-Camber Bubble Gauge
     

    Instrument with bubbles that indicate degree of tilt.

     
         
  • Catalytic Converter
     

    Device in the exhaust system that oxidizes most harmful emissions from the engine.

     
         
  • Cell
     

    An electrical energy storage device, consisting of negative and positive plates immersed in a conductive fluid (electrolyte).

     
         
  • Cell Voltage Test
     

    Check of individual battery cells for correct charge.

     
         
  • Center Support Bearing
     

    A ball or roller bearing unit that supports the middle of a two-piece drive shaft.

     
         
  • Centrifugal Advance
     

    A system that uses pivoting weights to advance timing as engine speed increases.

     
         
  • Certified Master Technician
     

    Auto technician who has passed all eight ASE tests.

     
         
  • Certified Technician
     

    Auto technician who has passed at least one ASE test.

     
         
  • Cetane Number
     

    An indication of the cold-starting ability of a diesel fuel.

     
         
  • CFM
     

    Cubic feet of air per minute.

     
         
  • Chain Slap
     

    Flapping motion of chain if slack is permitted.

     
         
  • Charcoal Canister
     

    Unit that traps and stores fuel vapors when engine is not running.

     
         
  • Charge Indicators
     

    Dash-mounted warning light, voltmeter, or ammeter used to show charging system status. Also the visual symbol (often a green dot) that shows state of charge in a battery.

     
         
  • Charging
     

    Current flowing into a battery from an alternator. Also, adding new or recycled refrigerant to an air conditioning or refrigeration system.

     
         
  • Charging Station
     

    Usually, a wheeled cart containing a tank of refrigerant, vacuum pump, and manifold set for adding refrigerant to an air conditioning system.

     
         
  • Charging System
     

    One that uses an alternator to replace the electrical energy drawn from the battery during starting.

     
         
  • Charging System Output Test
     

    A measurement of current and voltage output of the charging system under load.

     
         
  • Charging Voltage
     

    Alternator output that is higher than battery voltage (usually 1 3V- I 5V).

     
         
  • Chassis
     

    The frame and other parts of a vehicle other than the body.

     
         
  • Check Valve
     

    Valve that permits fuel flow in only one direction.

     
         
  • Chemical Burns
     

    Injury to the skin from exposure to toxic or corrosive chemical substances.

     
         
  • Chemical Flushing
     

    Method of removing scale buildup, using a strong chemical and water flush.

     
         
  • CID
     

    Cubic inch displacement.

     
         
  • Circuit Board
     

    A base upon which computer circuits are printed and components are mounted.

     
         
  • Circuit Breaker
     

    Device that interrupts current if a circuit is overloaded or a short occurs. Unlike a fuse, it can be reset.

     
         
  • Circuit Resistance Tests
     

    Measurements of resistance in the insulated and ground circuits of the system.

     
         
  • Clear Sight Glass
     

    A sign that the air conditioning system is operating properly.

     
         
  • Climate Control Computer
     

    ECM that controls temperature levels in the vehicle's passenger compartment.

     
         
  • Clogged Heater Core
     

    One that restricts or blocks flow of coolant, due to an accumulation of rust particles.

     
         
  • Closed Loop
     

    Control system that is constantly changing, based on inputs from sensors.

     
         
  • Closed System
     

    Cooling system using a recovery tank for coolant.

     
         
  • Cloud Point
     

    Temperature at which wax separates out of the fuel.

     
         
  • Cloudy Sight Glass
     

    A sign that desiccant from the receiver-drier is circulating through the air conditioning system.

     
         
  • Clutch
     

    Device that allows the driver to engage or disengage the engine and transmission.

     
         
  • Clutch Adjustment
     

    Process of setting the correct amount of free play in the release mechanism.

     
         
  • Clutch Cable
     

    A simple mechanical arrangement that uses a cable to transmit clutch pedal movement to the clutch fork.

     
         
  • Clutch Chatter
     

    A condition in which clutch severely vibrates as car accelerates.

     
         
  • Clutch Disc
     

    A disc that is splined to transmission input shaft and pressed against the face of the flywheel.

     
         
  • Clutch Fork
     

    Lever that forces the throw-out (release) bearing into pressure plate of clutch.

     
         
  • Clutch Lining
     

    Frictional material riveted to the face of the clutch disk.

     
         
  • Clutch Linkage
     

    A mechanical arrangement of levers and rods that transmits force from the clutch pedal to the clutch fork.

     
         
  • Clutch Master Cylinder
     

    The device that produces the hydraulic pressure needed to operate the clutch.

     
         
  • Clutch Pedal Free Travel
     

    Distance the pedal moves before the throw-out bearing acts on the pressure plate.

     
         
  • Clutch Pilot Shaft
     

    Tool used to keep clutch disc from falling as pressure plate is loosened during clutch disassembly.

     
         
  • Clutch Piston
     

    A piston that moves back and forth inside the clutch drum to clamp driving and driven discs together.

     
         
  • Clutch Release Mechanism
     

    Cable or linkage permitting driver to disengage clutch with foot pedal.

     
         
  • Clutch Slippage
     

    Condition in which engine rpm increases without increase in car's road speed.

     
         
  • Clutch Start Switch
     

    Safety switch that prevents starting motor operation until the clutch is disengaged.

     
         
  • CO
     

    Abbreviation for carbon monoxide, a toxic byproduct of partial burning of fuel.

     
         
  • C02 Readings
     

    Used to evaluate the air-fuel ratio of the engine; measured in percent by volume.

     
         
  • Coast Side
     

    Concave side of gear tooth.

     
         
  • Cogged Belt
     

    Rubber belt with built-in cogs (teeth) that engage the teeth of camshaft and crankshaft sprockets to form a positive drive.

     
         
  • Coil Oscillations
     

    Voltage fluctuations shown on an oscilloscope after the spark plug stops firing.

     
         
  • Coil Spring
     

    Length of spring steel rod wound into a spiral.

     
         
  • Coil Spring Compressor
     

    Tool used to safely compress a spring for removal or installation on a vehicle.

     
         
  • Coil Wire
     

    Conductor carrying high voltage from the coil to the distributor.

     
         
  • Cold Cranking Rating
     

    The amount of current a battery can deliver for 30 seconds at 0~F

     
         
  • Cold Plug
     

    One with a short insulator tip, used in engines operated at high speed.

     
         
  • Cold Soak Cleaner
     

    Cleaning method using unheated solvents to remove oil and grease from disassembled engine parts.

     
         
  • Cold Start Injector
     

    Valve that supplies extra fuel for cold starts.

     
         
  • Combination Valve
     

    One that includes both a suction valve and an expansion valve (used in air conditioning systems). Also braking system valve that can function as a metering or proportioning valve and a brake warning light switch.

     
         
  • Combination Wrench
     

    One that has an open jaw on one end and a box (closed end) on the other.

     
         
  • Combustion Chamber
     

    Area at the top of the cylinder where a spark plug ignites the compressed air-fuel mixture.

     
         
  • Combustion Leak Test
     

    Test that checks for presence of combustion gases in cooling system.

     
         
  • Commutator
     

    Sliding electrical connection between motor windings and brushes.

     
         
  • Commutator End Frame
     

    The end housing on a motor, holding the brushes, brush springs, and shaft bushing.

     
         
  • Compact Spare
     

    Small-diameter spare tire for use in emergencies.

     
         
  • Compression Gauge
     

    Dial indicator used to measure cylinder compression.

     
         
  • Compression Ignition
     

    Ignition of an air-fuel mixture by heat that results from high pressure (compression).

     
         
  • Compression Pressure
     

    The amount of pressure produced in the cylinder by the compression stroke.

     
         
  • Compression Ratio
     

    The relationship of cylinder volumes with the piston at TDC and at BDC

     
         
  • Compression Ring
     

    Ring that fills the gap between the piston and cylinder wall, preventing blow-by of compression pressure into the crankcase.

     
         
  • Compression Stroke
     

    Piston stroke that compresses the air-fuel mixture in the cylinder.

     
         
  • Compression Test
     

    To check of the compression developed in each engine cylinder and is a means of determining engine condition.

     
         
  • Compressor
     

    Device that pressurizes a refrigerant and forces it through a refrigeration system.

     
         
  • Compressor Assembly
     

    Motor-powered air pump that produces pressure for an electronic height-control system.

     
         
  • Compressor Housing
     

    Outer case around the compressor wheel section of turbocharger.

     
         
  • Compressor Shaft Seal
     

    A common point of refrigerant leakage in a system.

     
         
  • Compressor Wheel
     

    Fan-like wheel that forces air, under pressure, into the engine's intake manifold.

     
         
  • Computer
     

    Electronic device used to control many systems of modern vehicles.

     
         
  • Computer Amplifier
     

    Device that strengthens signals inside the computer.

     
         
  • Computer Analyzer
     

    A more complex testing instrument than a scanner.

     
         
  • Computer Clock
     

    Pacing device that keeps all input, processing, and output operations "in step."

     
         
  • Computer-Coil Ignition
     

    A distributor less ignition system using sensors, a control unit, and multiple ignition coils.

     
         
  • Computer Conditioner
     

    Interface that converts digital signals to analog and vice versa.

     
         
  • Computer Controlled Carburetor
     

    One that calculates and sets air-fuel ratio based on input from sensors.

     
         
  • Computer Harness Connector
     

    Plug at the end of a wiring harness, with one prong for each wire.

     
         
  • Computerized Emission Control System
     

    A computer controlled system that uses sensors, a catalytic converter, and fuel injection to minimize emissions of harmful substances.

     
         
  • Computer Memory
     

    Storage area where data is held electronically.

     
         
  • Computer Menu
     

    The list of tasks or programs initially shown on a computer screen

     
         
  • Computer Scan Values
     

    Output from the vehicle's computer system that can be read by a diagnostic scanner.

     
         
  • Computer Terminal Values
     

    Voltage and resistance values at the ECU connector, read by a digital VOM.

     
         
  • Computer Trouble Codes
     

    Numeric codes, shown on a display or as pulses, that indicate the nature or location of a problem.

     
         
  • Computer Voltage Regulator
     

    Device that provides a very smooth DC voltage for circuits and devices controlled by the computer.

     
         
  • Condensation
     

    Change from a gas to a liquid state.

     
         
  • Condenser
     

    An electrical component in contact point distributors that prevents arcing as points open and close. Also, a device that allows refrigerant to give off absorbed heat and change from a gas back to a liquid state.

     
         
  • Conduction
     

    Method of heat transfer through direct contact.

     
         
  • Conductor
     

    A material that permits easy flow of electrons.

     
         
  • Connecting Rod
     

    Part that fastens the piston to the crankshaft.

     
         
  • Connecting Rod Side Clearance
     

    Distance between side of the connecting rod and the side of the crankshaft journal.

     
         
  • Constant Velocity Joint
     

    One that uses two cross-and-roller joints connected by a centering socket and center yoke.

     
         
  • Contact Pattern
     

    The area of a gear tooth where the matching gear's tooth physically contacts it.

     
         
  • Contact Point Regulator
     

    An older type of voltage regulator that has largely been replaced by the electronic type.

     
         
  • Contact Points
     

    In older distributors, the spring-loaded electrical "make/break" switch contacts.

     
         
  • Continuous Injection
     

    Fuel injection that is constant.

     
         
  • Continuously Variable Transmission
     

    One that has an infinite number of driving ratios and uses belts and pulleys, rather than planetary gear sets.

     
         
  • Control Arm Bushing
     

    Sleeve that allows control arm to swing up and down.

     
         
  • Control Arms
     

    Movable lever arm that forms part of a vehicle's suspension system.

     
         
  • Control Rod
     

    A toothed shaft that rotates control sleeves to control the output of a diesel injector pump.

     
         
  • Control Sleeve
     

    Rotating sleeve around the plunger of a diesel injection pump that helps control pump output.

     
         
  • Convection
     

    A method of heat transfer through air or fluid medium.

     
         
  • Conventional Measuring System
     

    The system of feet, inches, pounds, etc., traditionally used in the United States.

     
         
  • Converter Housing
     

    Case containing the fluid coupling (torque converter) used with an automatic transmission.

     
         
  • Cooling System
     

    Radiator and other components that allow a coolant to circulate and maintain a constant engine operating temperature.

     
         
  • Cooling System Hydrometer
     

    Test instrument used to check specific gravity of coolant.

     
         
  • Cooling System Pressure Test
     

    A method of checking for leaks by placing system under pressure.

     
         
  • Cooperative Training
     

    Work release program combining school classes with work experience.

     
         
  • CO Readings
     

    When reading CO levels, an exhaust analyzer provides a percentage by volume output.

     
         
  • Cotter Pin
     

    A soft metal pin that fits through hole in a nut and is then spread to lock components in place.

     
         
  • Countershaft
     

    A Shaft on which cluster gears are mounted that transmits force from input gears to output gears.

     
         
  • Countershaft Gear
     

    Cluster of gears in a manual transmission that transmit force from input gears to output gears.

     
         
  • Cradle
     

    Sub-frame supporting the engine of some vehicles.

     
         
  • Crankcase
     

    Lower portion of the block, containing the crankshaft.

     
         
  • Crank Position Sensor
     

    Similar to a distributor pickup coil, the sensor is activated by the teeth on a pulse ring in a crankshaft triggered ignition system.

     
         
  • Crankshaft
     

    Component that changes the up-and-down motion of the pistons into rotating motion.

     
         
  • Crankshaft End Play
     

    End-to-end movement of crankshaft in block.

     
         
  • Crankshaft Front Oil Seal
     

    Component that keeps oil from leaking between the crankshaft snout and the engine front cover.

     
         
  • Crankshaft Position Sensor
     

    Device to monitor engine speed.

     
         
  • Crankshaft Pulley
     

    Pulley, attached to harmonic balancer, that drives belts for alternator and other units.

     
         
  • Crankshaft Triggered Ignition
     

    System that places trigger wheel and pickup coil on the crankshaft damper at the front of the engine.

     
         
  • Crankshaft Turning
     

    Grinding or otherwise smoothing the surface of crankshaft rod and main journals to repair damage or wear.

     
         
  • Creeper
     

    A low, wheeled cart used to work under a car supported by jackstands.

     
         
  • Crimping Pliers
     

    Special tool used to mechanically fasten connectors to wires.

     
         
  • Crisscross Pattern
     

    Typical pattern used to tighten cylinder head bolts to provide even pressure.

     
         
  • Crossflow
     

    Type of radiator arrangement with tubes running horizontally.

     
         
  • Crossover Pipe
     

    Connector between left and right header pipes in a dual exhaust system, used to equalize backpressure.

     
         
  • Curb Height
     

    Distance from a given point on the car to the ground.

     
         
  • Curb Weight
     

    Weight of vehicle with full gas tank and no passengers or cargo.

     
         
  • Current
     

    The flow of electrons through a conductor.

     
         
  • Cushioning Springs
     

    Flat springs under the friction material on the clutch disc that help smooth the clutch engagement.

     
         
  • CV
     

    Constant velocity.

     
         
  • CV-Joint Repair Kit
     

    Kit containing joint components, replacement boot, grease, and other necessary items for joint repair.

     
         
  • Cybernetics
     

    The study of how electrical-mechanical devices can duplicate actions of the human body.

     
         
  • Cylinder Balance Test
     

    Oscilloscope test that measures the power output from each of the engines cylinders.

     
         
  • Cylinder Block
     

    Another name for the engine block, or main body of the engine.

     
         
  • Cylinder Bore
     

    Diameter of the engine cylinder.

     
         
  • Cylinder Boring
     

    Machining of cylinder walls to make them perfectly straight and smooth, removing signs of wear and damage.

     
         
  • Cylinder Head
     

    Component that bolts to the top of the engine, enclosing the tops of the cylinders.

     
         
  • Cylinder Head Stand
     

    A fixture used to hold the cylinder head off the workbench surface.

     
         
  • Cylinder Hone
     

    A tool used to develop a pattern of fine scratches on cylinder walls to aid in new ring break-in.

     
         
  • Cylinder Leakage Tester
     

    Instrument used to determine amount of air leakage from combustion chamber.

     
         
  • Cylinder Out-of-Roundness
     

    Condition in which a cylinder diameter is different when measured front-to-back than when measured side-to-side.

     
         
  • Cylinder Sleeving
     

    The practice of inserting a liner into a bored cylinder to restore it to its original diameter.

     
         
  • Cylinder Taper
     

    The slight difference in diameter, due to wear, from the top to the bottom of an engine cylinder.

     
         
  • Cylinder Wear
     

    When the natural up and down movement of the engines piston physically erodes the cylinder walls.

     
         
  • Dash Light Code
     

    The Morse type trouble code conveyed by a flashing light on dashboard.

     
         
  • Dash Warning Light
     

    A labeled indicator that lights to show there is a problem of malfunction.

     
         
  • DC
     

    Direct current.

     
         
  • DC Generator
     

    Device that produces direct current.

     
         
  • Dead Axle
     

    A solid, straight rear axle on a front-wheel-drive vehicle.

     
         
  • Dead Battery
     

    One that has become discharged.

     
         
  • Dead Cylinder
     

    One in which the spark plug is not firing.

     
         
  • Decimal Conversion Chart
     

    Table showing equivalent quantities in fractions of an inch, decimal fractions, and millimeters.

     
         
  • Deck Warpage
     

    Twisting or distortion of engine block surfaces as a result of overhearing.

     
         
  • Delivery Valve
     

    Spring-loaded valves in the outlet fittings to diesel injector pump.

     
         
  • Detonation
     

    Explosive, uneven burning of fuel causing engine knock.

     
         
  • Diagnosis Chart
     

    A listing of problem causes and corrections.

     
         
  • Diagnostic Connector
     

    A terminal to which a diagnostic scanner can be connected to check vehicle operation.

     
         
  • Diagonally Split
     

    Term for a braking system that has each master cylinder piston actuating wheel cylinders that are diagonally opposed.

     
         
  • Diagrams
     

    Drawings that are used to show wiring, vacuum, or hydraulic systems.

     
         
  • Dial Bore Gauge
     

    A tool used to quickly and accurately measure cylinder taper.

     
         
  • Dial Indicator
     

    A device used to measure tiny movements and display the distance on a dial.

     
         
  • Diaphragm Spring Clutch
     

    One that uses a single diaphragm spring, rather than several coil springs, to help release the clutch disk.

     
         
  • Die
     

    Tool for cutting threads on the outside of a rod or shaft.

     
         
  • Diesel Cylinder Balance Test
     

    Diagnostic procedure to determine whether cylinders are firing properly.

     
         
  • Diesel Engine Maintenance
     

    Since diesel engines do not have ignition systems, maintenance (tune-up) work is primarily devoted to making adjustments, changing oil, and replacing filters.

     
         
  • Diesel Fuel Grade
     

    Viscosity rating of a diesel fuel.

     
         
  • Dieseling
     

    Continued engine operation with the ignition turned off (also called "run-on").

     
         
  • Diesel Injection
     

    A mechanical system that forces diesel oil directly into combustion chambers.

     
         
  • Diesel Injection System Tester
     

    Device used to test a number of diesel components and functions by checking pressures.

     
         
  • Diesel Maximum Speed Adjustment
     

    A limitation that can be set by using an adjusting screw on the injection pump.

     
         
  • Diesel Tachometer
     

    Device used to establish the revolutions per minute of a diesel engine.

     
         
  • Differential
     

    An assembly of gears used to provide power to the rear axles and allow them to rotate at different speeds as necessary.

     
         
  • Differential Carrier
     

    Component used to mount the differential assembly on the rear axle housing.

     
         
  • Differential Case
     

    Case that holds the ring gear, spider gear, and inner ends of the axles.

     
         
  • Differential Lubricant
     

    High viscosity oil used to reduce friction between differential components.

     
         
  • Differential Yoke
     

    Component that connects the rear universal of the drive line to the differential.

     
         
  • Digital Code
     

    Trouble code displayed as actual digits (numbers), rather than flashes.

     
         
  • Digital Display
     

    An oscilloscope that displays a numerical reading (digital display) on a separate screen.

     
         
  • Digital Pyrometer
     

    An electronic device for making accurate temperature measurements.

     
         
  • Digital Signal
     

    One made up of strictly on-off (or high-low) pulses.

     
         
  • Dimmer Switch
     

    A switch that controls high-beam and low-beam headlamp functions.

     
         
  • Diode
     

    Electronic device that allows current flow in only one direction.

     
         
  • Diode Test
     

    Check for open or shorted conditions in a diode, using an ohmmeter or special test equipment.

     
         
  • Dipstick
     

    Strip of stiff metal used to check fluid levels. Markings indicate whether more fluid must be added.

     
         
  • Disc Brakes
     

    Brakes using a caliper that clamps against a rotor for stopping.

     
         
  • Disc Brake Service
     

    Procedure involving worn pad replacement, caliper rebuilding, rotor surfacing, and system bleeding.

     
         
  • Discharging
     

    Flowing out (describing current movement related to a battery).

     
         
  • Disc Resurfacing
     

    Machining the rotor surface to remove wear marks or correct run out.

     
         
  • Disc Run out
     

    Amount of side-to-side movement of brake disc (rotor).

     
         
  • Displacement
     

    The volume displaced by the pistons in moving from BDC to TDC.

     
         
  • Display Output
     

    Actuator that provides readable characters on a small screen or liquid crystal display.

     
         
  • Distilled Water
     

    Water that has been purified.

     
         
  • Distributor Cap
     

    A plastic, insulating cover that encloses the distributor rotor and other components.

     
         
  • Distributor Injection Pump
     

    A pump that uses one or two cylinders to handle injection of diesel fuel for an engine, as compared to an inline pump with a plunger for each cylinder.

     
         
  • Distributor Point Gap
     

    Recommended distance between points when fully open.

     
         
  • Distributor Rotor
     

    A slotted shaft on a distributor injector pump that controls fuel flow to each nozzle.

     
         
  • Distributor Tester
     

    Test device used to check operation of an ignition system distributor.

     
         
  • Distributor Wrench
     

    A specially shaped wrench that allows technician to reach under distributor housing to adjust timing.

     
         
  • Diverter Valve
     

    Component that prevents air from entering the exhaust system during deceleration.

     
         
  • DOHC
     

    Dual Overhead Cam engine.

     
         
  • DOT Number
     

    The Department of Transportation code that indicates the tire has passed required safety rests. It also identifies manufacturer, construction type, and other data.

     
         
  • Double Lap Flare
     

    Approved method of preparing steel fuel lines for connection.

     
         
  • Down flow
     

    Type of radiator arrangement with tubes running vertically.

     
         
  • Dragging Brakes
     

    Braking friction material that remains partially applied, even after the brake pedal is released.

     
         
  • Dragging Clutch
     

    Failure of friction disc to fully disengage from flywheel, even though clutch pedal is depressed.

     
         
  • Draw-Through Turbo
     

    A turbocharger located behind the compressor or throttle body. It compresses the air-fuel mixture.

     
         
  • Drilled Rod
     

    Connecting rod with an oil passage drilled through its length to deliver oil to the piston pin.

     
         
  • Drive Chain
     

    A chain used with some longitudinally mounted engines to transfer power from the engine crankshaft to the transaxle.

     
         
  • Drive Housing
     

    Case surrounding the pinion gear on a starter motor.

     
         
  • Drive Line
     

    The parts that transfer power from the transmission to the drive wheels.

     
         
  • Drivers
     

    Power transistors in a computer that control current flow to actuators.

     
         
  • Drive Shaft
     

    Steel tube that transfers rotating motion from transmission to rear wheels of a car.

     
         
  • Drive Shaft Angle
     

    The angle at which the drive line meets the differential or the transmission.

     
         
  • Drive Shaft Assembly
     

    Components between the transmission and differential, including front and rear yokes, universal joints, and a drive shaft.

     
         
  • Drive Shaft Balance
     

    Equal weight distribution around the axis of the shaft.

     
         
  • Drive Shaft Noise
     

    Sounds typically caused by worn U-joints, worn slip joints, or a faulty center support bearing.

     
         
  • Depreciation
     

    Loss of value of a vehicle due to age and mileage, as well as physical condition.

     
         
  • Detonation
     

    Slang for pinking or engine knock (US pinging); uncontrolled secondary explosion in the combustion chamber occurring after the spark.

     
         
  • Diagnostic Fault-Code
     

    Numerical code that indicates problems in the computer system. (US Diagnostic Trouble Code)

     
         
  • Diesel
     

    An internal combustion engine that fires without the use of an ignition system. Diesel engines use high compression to fire the mixture in the cylinders. Uses oil rather than petrol, no spark ignition system.

     
         
  • Dieseling
     

    The engine seems to continue running after the ignition has been turned off; run-on that occurs when a petrol engine is idling too high. Differential A geared unit that allows the wheels on opposite sides of the vehicle to turn at different speeds. This is vital while turning.

     
         
  • Diminished Value
     

    The value established by comparing the pre-accident value of a vehicle, the amount of damage to the vehicle, and the post-repair value of the vehicle.

     
         
  • Dipstick
     

    A calibrated measuring rod for checking the level of fluids, e.g. oil

     
         
  • Direct Drive
     

    A condition where the transmission connects the engine to the differential directly without altering the gear ratio.

     
         
  • Dismantle
     

    to take a used vehicle apart for the purpose of reclaiming usable parts. Dismantling takes place in a dismantling bay.

     
         
  • Dismantler
     

    term describing anyone who takes a vehicle apart.

     
         
  • Dismantling Bay
     

    An area used by the dismantler to pull parts from vehicles. Often equipped with machinery to safeguard equipment environment and persons.

     
         
  • Distributor
     

    A rotary switch that distributes the high voltage ignition spark and delivers it to the proper cylinders at the right moment.

     
         
  • Distributor-less ignition
     

    An electronic ignition system that creates spark without the use of a mechanical distributor using signals from electrical sensors on the crankshaft.

     
         
  • Driveshaft
     

    The rotating shaft that transfers power from the transmission to the differential on rear-wheel drive cars. Propeller shaft.

     
         
  • Drive wheel
     

    Any wheel that transmits driving power from the engine to the road.

     
         
  • Dynamometer
     

    A set of rollers designed to provide a load to simulate actual driving conditions while in the shop.

     
         
  • Drive Shaft Run out
     

    Lack of straightness, due to being bent or because of U-joint wear.

     
         
  • Drive Shaft Vibration
     

    A rapid oscillation caused by a shaft imbalance or excessive shaft run out.

     
         
  • Drive Side
     

    Convex side of gear tooth.

     
         
  • Drive Size
     

    The size of the square opening for the handle of a socket wrench set.

     
         
  • Driving Hub
     

    Mounting for wheel on end of axle.

     
         
  • Driving Range
     

    Distance a vehicle can be driven without refueling.

     
         
  • Drop Light
     

    An electrical extension cord with a light bulb in a safety cage attached.

     
         
  • Dropping Brake Pedal
     

    Slow descent of brake pedal to floor when brakes are applied. Usually caused by internal leak in master cylinder.

     
         
  • Drum
     

    The housing that holds the parts of a clutch assembly for an automatic transmission.

     
         
  • Drum Brakes
     

    System that forces brake shoes against the inside of a rotating drum to stop vehicle.

     
         
  • Drum Brake Service
     

    Process that involves dismounting, disassembling, cleaning, and replacing parts as necessary. Usually, shoes are replaced, wheel cylinders replaced or rebuilt, and the drum is turned (resurfaced). System is then reassembled, bled, and tested.

     
         
  • Drum Grinding
     

    Sometimes done to remove hard spots on a brake drum.

     
         
  • Drum Maximum Diameter
     

    Largest inside diameter allowed for safe operation of drum brakes.

     
         
  • Drum Resurfacing
     

    Machining of brake drum to remove surface damage.

     
         
  • Dry Charged
     

    Battery that is filled with electrolyte just before being installed in a vehicle.

     
         
  • Dry Park Test
     

    Visual check for looseness of steering components.

     
         
  • Dry Sleeve
     

    A thin cylinder liner that is not exposed to coolant.

     
         
  • Dual Reservoir Master Cylinder
     

    Brake system pump with two pistons and fluid reservoirs for safety.

     
         
  • Dummy Shaft
     

    Tool used to drive out countershaft and reverse idler shaft when disassembling manual transmission.

     
         
  • Dust Cap
     

    Metal cover on end of axle or spindle to keep grease in and road dirt out of bearings.

     
         
  • Dwell
     

    The amount of time distributor points remain closed between openings.

     
         
  • Dwell Meter
     

    One that measures point setting in degrees of distributor rotation.

     
         
  • Dwell Section
     

    Section of oscilloscope pattern used to identify problems in the distributor or electronic control unit.

     
         
  • Dwell Signal
     

    Electronic signal output by carburetor that can be read on a special meter for troubleshooting.

     
         
  • Dwell Variation
     

    Change in meter readings indicating distributor wear.

     
         
  • Dye Penetrate
     

    A testing material that can be sprayed on aluminum or cast iron engine parts to locate cracks.

     
         
  • Dynamic Imbalance
     

    Tire imbalance that causes both up-and-down and side-to-side movement while rotating.

     
         
  • Dynamometers
     

    Instrument used to measure power output and performance of an engine.

     
         
  • Dyno
     

    An engine dynamometer, used to measure brake horsepower.

     
         
  • Early Model
     

    An old production. For example early model vehicles would be vehicles produced more than 15 years ago.

     
         
  • eBay Power Seller
     

    A seller on eBay that maintains a high volume of sales and high standards in customer service.

     
         
  • Electrolysis
     

    A chemical process for developing electricity; decomposition of a substance by passing of an electric current through an electrolyte.

     
         
  • Electronic Parts
     

    In late-model vehicles. Includes electronic fuel or ignition systems, computer boards

     
         
  • ELV
     

    End-of-Life Vehicle: any vehicle that is deemed to be for parts or recycling only.

     
         
  • Engine Block
     

    The large part of the engine that houses the cylinders and water jacket; a metallic casing with a bore for each piston.

     
         
  • Engine Control Module
     

    Electronic controller; computer that controls the engine operation only.

     
         
  • Evaporator
     

    Heat exchanger that transfers heat from the passenger compartment to the A/C refrigerant.

     
         
  • Exhaust
     

    The expulsion of waste gasses after combustion.

     
         
  • Exhaust Gas
     

    Recirculation Valve that allows a metered amount of exhaust into the intake to reduce combustion temperature. Lowers nitrous oxide levels.

     
         
  • Exhaust Manifold
     

    A steel or cast series of channels that collect exhaust from the cylinders and direct it to the exhaust system.

     
         
  • Expansion Valve
     

    Variable orifice that forces refrigerant to expand and take on heat. This makes the refrigerant very cold.

     
         
  • Extras
     

    Accessories that may be fitted by the manufacturer, dealer or owner.

     
         
  • ECA
     

    Electronic control assembly; another name for an automotive computer.

     
         
  • ECM
     

    Electronic control module; another name for an automotive computer.

     
         
  • ECU
     

    Electronic control unit; another name for an automotive computer.

     
         
  • Effective Plunger Stroke
     

    The amount of plunger movement that pressurizes fuel in a diesel injector pump.

     
         
  • EFI
     

    Electronic fuel injection.

     
         
  • EFI Self-Diagnosis
     

    The ability of an electronic fuel injection system to display trouble codes.

     
         
  • EFI Tester
     

    A diagnostic device used with EFI systems that do not feature self-diagnosis.

     
         
  • EFI Trouble Code
     

    A digital display or on-off sequence that shows a number code for problem identification.

     
         
  • EGR Valve
     

    Air Gas Re-circulation Valve. A valve allowing exhaust gases to re-enter the intake manifold to be burned again, reducing cylinder temperature and some types of toxic emissions.

     
         
  • Electrical Fire
     

    One that involves, or begins in, electrical wiring.

     
         
  • Electric Engine Fan
     

    One operated by an electric motor, under control of a thermostatic switch.

     
         
  • Electric Fuel Pump
     

    An electrical device that uses a rotary motion to move fuel.

     
         
  • Electrolyte
     

    Liquid that surrounds the plates of a battery and allows a free flow of electrons.

     
         
  • Electronic Advance
     

    A system that uses sensor input and the vehicle's computer to control spark timing.

     
         
  • Electronic Airbag System
     

    System using impact sensors to deploy an airbag that cushions vehicle operator (and in some cases, passengers) in a collision.

     
         
  • Electronic Coil Module
     

    Grouping of ignition coils and the control unit needed to operate them.

     
         
  • Electronic Control Unit
     

    Another term for a computer used in a vehicle.

     
         
  • Electronic Ignition System
     

    One that uses an electronic control circuit and distributor pickup coil points and condensers to break the field of the ignition coil, sending voltage to the spark plug.

     
         
  • Electronic Ignition Tester
     

    Instrument used to identify source of ignition problems.

     
         
  • Electronic Modules
     

    Small computers in a vehicle, used for specific systems (such as anti-lock brakes or climate control).

     
         
  • Electronic Regulator
     

    Solid-state regulator separate from the alternator.

     
         
  • Electronic Shock Absorber System
     

    One that uses a computer, actuators, and adjustable shock absorbers to regulate stiffness of the vehicle's suspension.

     
         
  • Electronic Steering Assist
     

    Power steering system using an electric motor, rather than hydraulic components.

     
         
  • Electronic Transmission/Transaxle Control System
     

    A computer-based system that controls shift points and torque converter lockup for improved fuel economy.

     
         
  • Element
     

    One of the cells that can be combined to form a battery.

     
         
  • Emergency Brake
     

    Mechanical means of applying rear brakes.

     
         
  • Emission Control System
     

    Components and adjustments used to reduce the amount of pollutants released by operation of an automobile.

     
         
  • Engine
     

    The propulsion system that provides motive power for a vehicle.

     
         
  • Engine Analyzer
     

    Grouping of instruments used to check various engine functions and components.

     
         
  • Engine Blow-By
     

    Leakage of unburned fuel and other pollutants past piston rings and into the crankcase.

     
         
  • Engine Bottom End
     

    The block, crankshaft, connecting rods, pistons, and related components.

     
         
  • Engine Break-in
     

    Sequence of acceleration, deceleration, and other operations designed to properly seat and seal new piston rings.

     
         
  • Engine Crane
     

    A portable, wheeled hoist used to lift and remove engines from vehicles.

     
         
  • Engine Efficiency
     

    Ratio of power produced by the engine to the power supplied to that engine.

     
         
  • Engine Firing Order
     

    The sequence in which spark plugs are fired.

     
         
  • Engine Flooding
     

    Excess fuel in the intake manifold, preventing starting.

     
         
  • Engine Front Cover
     

    Housing of sheet metal or cast aluminum that covers the timing chain or gears.

     
         
  • Engine Front End
     

    A combination of components that operates the camshaft.

     
         
  • Engine Miss
     

    Roughness in engine operation, indicating failure of a spark plug to fire.

     
         
  • Engine Off Self-Test
     

    Test conducted with engine off but ignition key on to cause displaying of trouble codes.

     
         
  • Engine On Self-Test
     

    One conducted with the engine fully warmed up, allowing check of the sensors under normal conditions.

     
         
  • Engine Operating Temperature
     

    Temperature reached by coolant during normal engine operation.

     
         
  • Engine Overhaul
     

    Process of servicing all internal parts of an engine.

     
         
  • Engine Sensors
     

    Devices that monitor temperatures, fluid levels, and other engine conditions for computer input.

     
         
  • Engine Smoke
     

    Emissions during acceleration or deceleration. Color can indicate engine condition.

     
         
  • Engine Surge
     

    Rise and fall of engine speed in cruising operation.

     
         
  • Engine Temperature Sensor
     

    Component that measures temperature of engine coolant.

     
         
  • Engine Top End
     

    The cylinder heads, valves, camshaft, and related parts.

     
         
  • Engine Torque
     

    A rating of turning force at the engine crankshaft.

     
         
  • Engine Tune-up
     

    A process of parts replacement and adjustment to return an engine to its peak performance.

     
         
  • EPROM
     

    Erasable programmable read-only memory.

     
         
  • Erasing Trouble Codes
     

    Removing trouble codes from computer memory after they have been read and the problems corrected.

     
         
  • Ethyl Alcohol
     

    Grain alcohol or ethanol.

     
         
  • Evacuation
     

    A process of removing air and moisture from an emptied air conditioning system, using a vacuum pump.

     
         
  • Evaporator
     

    A device in which refrigerant changes from a liquid to a gas and absorbs heat from its surroundings.

     
         
  • Exhaust Gas Analyzer
     

    Testing device to measure the chemical content of exhaust gases.

     
         
  • Exhaust Gas Sensor
     

    See oxygen sensor.

     
         
  • Exhaust Manifold
     

    Component that directs output of the exhaust ports to the exhaust system.

     
         
  • Exhaust Manifold Heat Valve
     

    A component that forces hot exhaust gases to circulate through intake manifold as an aid to cold-weather starting.

     
         
  • Exhaust Stroke
     

    Piston stroke that forces byproducts of combustion out of the cylinder.

     
         
  • Exhaust System
     

    Components that quiet engine operation and direct combustion products (exhaust gases) to the rear of the vehicle.

     
         
  • Expander-Spacer
     

    Metal ring used with two rails to form oil control ring.

     
         
  • Expansion Plug
     

    Freeze plug designed for installation in tight quarters.

     
         
  • Expansion Tube
     

    A device with a small orifice that meters refrigerant into the evaporator of an air conditioning system.

     
         
  • Expansion Valve
     

    Temperature-sensitive valve that controls refrigerant flow and air conditioner evaporator temperature.

     
         
  • Extension Housing
     

    A separate housing bolted to the transmission housing, containing the output shaft and rear oil seal.

     
         
  • External Oil Leakage
     

    Escape of oil from the engine, usually around gaskets or seals.

     
         
  • Failsafe Brakes
     

    An air brake system whereby loss of air pressure causes springs to apply the brakes.

     
         
  • Fan belt
     

    A belt with a rubber and fiber structure, used to drive auxiliaries from the engine; water pump, cooling fan, ac compressor, air compressor etc.

     
         
  • Fast Idle
     

    1. A condition used during cold operation to increase idle speed so the engine will run with a richer mixture.
    2. A higher than normal idle speed due to the operation of a choke, or when the ac compressor or other auxiliaries are running.

     
         
  • Filter
     

    A screen or mesh through which gas or a liquid passes to remove impurities.

     
         
  • Final Bill
     

    Itemized repair invoice detailing what repairs were actually performed (not just an estimate of repairs). Included in the itemized statement will be codes designating the type of parts used.

     
         
  • Firewall
     

    The bulkhead between the engine and the passenger compartment.

     
         
  • First Party Claimant
     

    Vehicle Owner's insurance company will be paying for the costs of the repairs.

     
         
  • Fluid Recovery system
     

    The system the automotive recycler has set up to collect and recycle or dispose of the fluids remaining in salvage vehicles in an environmentally responsible fashion

     
         
  • Flywheel
     

    Plate mounted to the back of the engine with a gear for the starter to turn the engine.

     
         
  • Frame
     

    Chassis of a vehicle. The square, rectangular, or tubular steel undercarriage that has the suspension, drive train, engine and body bolted to it.

     
         
  • Front Wheel Drive
     

    A vehicle in which the engine drives the front wheels. Fuel A combustible substance, usually a hydrocarbon; petrol diesel, gas.

     
         
  • Fuel Cell
     

    A catalyst that creates electricity by combining hydrogen and oxygen into water.

     
         
  • Fuel Charge
     

    The air-fuel mixture in the combustion chamber.

     
         
  • Fuel Injector
     

    A small valve, usually electronically controlled, that controls the amount of fuel entering the engine.

     
         
  • Fuel Pump
     

    An electrical or mechanical pump that delivers fuel from the tank to the carburetor or injection system.

     
         
  • Full Flow Oil Filter
     

    A filtering system that filters all of the oil before it is circulated around the engine.

     
         
  • Face
     

    Area of a gear tooth above the pitch line.

     
         
  • Fast Charge(r):
     

    A charger or charge that provides a high current flow for quickly recharging a battery.

     
         
  • Fastener
     

    Devices that hold parts together.

     
         
  • Fast Flushing
     

    Flushing system through a heater hose fitting, without removing the thermostat.

     
         
  • Fast Idle Cam
     

    A cam that increases idle speed when the choke is closed.

     
         
  • Fast Idle Solenoid
     

    Device that holds throttle plates open when engine is operating, but lets them almost close when engine is shut off.

     
         
  • Feathered Edge
     

    One side of each tread rib is worn sharp and raised; the other side is rounded or recessed.

     
         
  • Feeler Gauge
     

    A thin metal strip or wire of identified thickness, used to measure clearance.

     
         
  • Fender Cover
     

    Cloth or plastic blankets placed over auto body sections to protect the finish while repairs go on.

     
         
  • fhp
     

    Frictional horsepower.

     
         
  • Field Frame
     

    Housing on a motor that holds the field coils.

     
         
  • Field Windings
     

    Stationary windings in a motor that creates a magnetic field to keep the armature rotating.

     
         
  • Filler Neck Restriction
     

    Metal piece preventing introduction of the larger fuel nozzle used for leaded fuel.

     
         
  • Fill Ring
     

    Electrolyte level indicator in older style batteries.

     
         
  • Firing Line
     

    The tall spike shown on an oscilloscope, representing the voltage needed to make the spark jump the plug gap.

     
         
  • Firing Order
     

    Sequence in which the spark plugs fire in cylinders.

     
         
  • Fixed Caliper
     

    Brake caliper rigidly mounted to steering knuckle.

     
         
  • Flank
     

    Area on a gear tooth below the pitch line.

     
         
  • Flex Fan
     

    One with blades that alter airflow with engine speed.

     
         
  • Float
     

    Device that rises and falls with fuel level in bowl, opening and closing the needle valve.

     
         
  • Floating Caliper
     

    Brake caliper mounted on t\VO rubber bushings, allowing some movement.

     
         
  • Fluid Contamination
     

    Inclusion of foreign matter in transmission fluid.

     
         
  • Fluid Coupling Fan Clutch
     

    Clutch designed to slip at higher fan speeds.

     
         
  • Fluid Varnish
     

    Sticky, glue-like substance resulting from breakdown of automatic transmission fluid.

     
         
  • Flywheel
     

    Large, heavy wheel mounted on the rear end of the crankshaft. Usually includes a ring gear that is engaged by the starter pinion.

     
         
  • FM
     

    Frequency modulation (type of radio broadcasting).

     
         
  • Force
     

    A pushing or pulling action.

     
         
  • Forward Bias
     

    Arrangement in which diode acts as a conductor.

     
         
  • Four-Gas Analyzer
     

    Measuring instrument that provides the reading of oxygen and carbon dioxide, as well as HC and CO, levels in exhaust.

     
         
  • Four-Stroke Cycle
     

    An engine that takes four piston movements (intake, compression, power, exhaust) to complete a cycle.

     
         
  • Frame
     

    The strong steel structure that supports the body of a vehicle.

     
         
  • Friction Bearing
     

    A Plain bearing with two smooth surfaces sliding on each other. Not a tapered bearing with an outside cone used as the race or riding surface.

     
         
  • Front Cover Gasket
     

    Thin sealing component that is compressed between the cover and the engine.

     
         
  • Front Drive Axles
     

    Shafts that transfer power from the transaxle differential to the vehicle's wheels.

     
         
  • Front End Rack
     

    Alignment stand.

     
         
  • Fuel Accumulator
     

    Diaphragm that dampens pressure pulses in a fuel injection system.

     
         
  • Fuel Distributor
     

    Hydraulically operated valve used to control fuel flow in a continuous injector system.

     
         
  • Fuel Vaporization System
     

    A combination of technologies and components that prevents fuel vapors from entering the atmosphere.

     
         
  • Fuel Heater
     

    A device used to warm diesel fuel and keep it from jelling into a semi-solid during cold weather.

     
         
  • Fuel Injection System
     

    General term for systems used with either gasoline or diesel fuel.

     
         
  • Fuel Injector
     

    Fuel valve controlled by a coil or solenoid.

     
         
  • Fuel Pressure Regulator
     

    System that controls pressure of fuel entering injector valves.

     
         
  • Fuel Pump Pressure
     

    The pressure of a fuel pump's output.

     
         
  • Fuel Pump Vacuum
     

    The amount of "pull" exerted on fuel by the pump.

     
         
  • Fuel Pump Volume
     

    The amount of fuel discharged by a pump in a measured period.

     
         
  • Fuel Rail
     

    Tubing that connects several injectors to the main fuel line.

     
         
  • Fuel Return System
     

    One that keeps cool fuel circulating to prevent vapor lock.

     
         
  • Fuel Tank Capacity
     

    How much fuel a tank can hold.

     
         
  • Full-Floating Piston Pin
     

    One that is free to rotate. It is secured in place with snap rings.

     
         
  • Full Flow Lubrication System
     

    One that forces all oil through a filter before it reaches the parts to be lubricated.

     
         
  • Fully Synchronized Transmission
     

    One in which all forward gears are equipped with synchronizers to allow downshifting while in motion.

     
         
  • Fuse
     

    Device that interrupts current if a circuit is overloaded or a short occurs.

     
         
  • Gas Flow
     

    The movement of air-fuel mixture into, or exhaust fumes out from, an engine.

     
         
  • Gasket
     

    A layer of soft material clamped between 2 firm surfaces to form a seal.

     
         
  • Gear
     

    A toothed wheel that meshes with another to transmit power from one shaft to another.

     
         
  • Gear Ratio
     

    The difference in the number of rotations between the engine crankshaft and the transmission output shaft, which allows the transmission to vary speed and torque.

     
         
  • Generator
     

    Magnetic windings that the engine turns to create a voltage to keep the battery charged.

     
         
  • Glow Plug
     

    A small electric heater in the cylinder on some diesel engines that provides additional heat during cold starting.

     
         
  • Gold Seal Certification
     

    Awarded to professional members of the Automotive Recyclers Association who have completed the Certified Automotive Recycler's Program. Recyclers must meet 27 categories of requirements and agree to follow a number of strict professional business practices, rules and regulations.

     
         
  • Governor
     

    1. A device which controls the occurrence of each gear change in an automatic transmission to match road speed and engine speed.
    2. A device which limits engine speed, either mechanically or electronically.

     
         
  • Gas Charged Shock
     

    Type that contains low-pressure gas to keep the oil from foaming, and thus improve performance.

     
         
  • Gasket
     

    A soft, flexible material placed between two parts to prevent leaks. Common materials used include cork, polyurethane and sometimes asbestos.

     
         
  • Gasket Scraper
     

    A metal tool used to remove pieces of gasket and hardened oil or carbon deposits from engine parts.

     
         
  • Gas Line Freeze
     

    Condition caused by moisture in fuel turning to ice and blocking fuel line.

     
         
  • Gasohol
     

    Gasoline with from 2 to 20 percent alcohol added.

     
         
  • Gasoline Injection
     

    System that uses computers, sensors and electrically operated injectors to meter fuel into an engine.

     
         
  • Gas Turbine
     

    Engine that uses burning and expanding fuel vapor to spin fan-type blades

     
         
  • Gear Backlash
     

    Small amount of clearance between meshing gear teeth.

     
         
  • Gearbox Overhaul
     

    Disassembly, cleaning, adjusting, and replacing parts as necessary.

     
         
  • Gearbox Ratio
     

    The relationship (number of turns) between the steering wheel and the sector gear.

     
         
  • Gear Clash
     

    A noise that is heard when gears fail to mesh properly in a manual transmission.

     
         
  • Gear Oil
     

    High viscosity oil (80W or 90W) used in transmissions.

     
         
  • Gear Pump
     

    Oil pump using meshing gears to provide pressure and oil movement.

     
         
  • Gear Ratio
     

    The number of rotations a driving gear must make while the driven gear is completing one revolution.

     
         
  • Gear Reduction
     

    The situation in which a small gear is used to drive a larger gear, with an increase in torque as a result.

     
         
  • General Repair Manual
     

    Service manual covering many makes and models of cars, usually over a several-year span.

     
         
  • Glow Plug
     

    A heating element that helps start a diesel in cold weather.

     
         
  • Glow Plug Resistance-Balance Test
     

    A diagnostic procedure used to determine whether all cylinders of a glow plug equipped diesel engine are firing.

     
         
  • Governor
     

    A device used to control an engine's speed.

     
         
  • Grabbing Brakes
     

    Abrupt, hard application of brakes when pedal is only lightly depressed.

     
         
  • Grade Markings
     

    Lines on bolt head, indicating tensile strength.

     
         
  • Grease Gun
     

    Tool used to inject lubricating grease, under pressure, into fittings.

     
         
  • Grease Job
     

    Process of forcing a thick lubricant, under pressure, into friction points on the chassis, steering system, and driveline.

     
         
  • Grease Rack
     

    Lift used to raise car for lubrication or other work.

     
         
  • Grease Seal
     

    Component that prevents lubricant leaking from axle assembly into steering knuckle or bearing support.

     
         
  • Gross HP
     

    Horsepower developed with only basic accessories in use.

     
         
  • Group Injection
     

    Operation of some (usually half) of the injectors simultaneously.

     
         
  • Growler
     

    Testing device used to check armatures for shorts.

     
         
  • Hard Parts
     

    All parts, other than sheet metal, that is hard: motor, transmission, brakes, wheels etc.

     
         
  • Head Gasket
     

    See cylinder head gasket.

     
         
  • Hesitation
     

    A momentary lack of response to acceleration.

     
         
  • Hollander Number
     

    Industry standard inventory language to identify parts and part assemblies.

     
         
  • Hybrid
     

    A bi-fuel, dual fuel, or multi-fuel vehicle typically powered by petrol, diesel or gas, and secondly by electricity.

     
         
  • Hydraulics
     

    The use of pressurized liquid to transfer force or motion.

     
         
  • Hydrocarbons
     

    Raw unburned gasoline; reacts with sunlight to create photo chemical smog.

     
         
  • Hydrometer
     

    Device for measuring coolant protection level.

     
         
  • Hard Steering
     

    Greater than normal effort needed to turn steering wheel.

     
         
  • Hard to Shift
     

    A manual transmission problem often caused by damaged or sticking linkage.

     
         
  • Hard to Start Problem
     

    Usually caused by a partial system failure, such as a choke refusing to open.

     
         
  • Harmonic Vibration
     

    A high-frequency vibration caused by the crankshaft.

     
         
  • Harsh Shifts
     

    Transmission changes gears in a jerky manner.

     
         
  • HC
     

    Abbreviation for hydrocarbons (unburned fuel).

     
         
  • HC Readings
     

    The parts-per-million measuring of hydrocarbon emission.

     
         
  • Header Pipe
     

    Steel tubing connecting the exhaust manifold to the catalytic converter.

     
         
  • Head Gasket Markings
     

    Lines or words printed on gasket to indicate proper installation orientation.

     
         
  • Head Gasket Torque Sequence
     

    Tightening head bolts in specified sequence and in several stages of torque.

     
         
  • Headlamp System
     

    Components, such as battery, switches, fuses and lamps that make up the headlamp lighting circuit.

     
         
  • Headlight Aimer
     

    Device used to adjust headlights to specified positions.

     
         
  • Headlight Aiming Screen
     

    Set of measured lines on a wall, used to adjust headlight aim.

     
         
  • Heater Core
     

    A radiator-like unit that circulates heated engine coolant through a series of tubes. A fan blows air past the tubes to heat the passenger compartment of the vehicle.

     
         
  • Heater Hoses
     

    Flexible tubes that carry heated coolant between engine and the heater core.

     
         
  • Heating System
     

    Components that use engine cooling system heat to warm an automobile passenger compartment.

     
         
  • Heat Shields
     

    Metal plates that keep exhaust heat from transferring to other parts of the vehicle.

     
         
  • Heel
     

    The wide part of a gear tooth.

     
         
  • Height Sensor
     

    Lever-operated switch that reacts to changes in car-body height.

     
         
  • Height Sensor Link
     

    Rods that connect height sensor to suspension system.

     
         
  • Helical Gears
     

    Those with teeth cut at an angle to the centerline of the drive shaft.

     
         
  • Helicoil
     

    Spring steel insert used to repair damaged internal threads.

     
         
  • Hemi Chamber
     

    A dome-shaped (hemispherical) combustion chamber.

     
         
  • Hesitation
     

    Condition in which engine does not accelerate immediately when gas pedal is pressed.

     
         
  • High Side
     

    Section of an air conditioning system in which refrigerant is under high pressure.

     
         
  • Holding Tools
     

    Vises, clamps, and fixtures that grip a part while it is being worked on.

     
         
  • Honing Grit
     

    Fine bits of stone and metal remaining after a cylinder is honed. This material must be removed from the engine before it is reassembled, or it will cause severe wear.

     
         
  • Hall Effect
     

    A type of pickup used with many electronic ignition systems.

     
         
  • Halogen Headlamp
     

    One with a small, high-intensity halogen lamp inside a conventional scaled housing.

     
         
  • Hangers
     

    Rubber and metal fasteners that suspend the exhaust components from the underside of the vehicle.

     
         
  • Hard Failure
     

    One that is always present (not intermittent), such as a disconnected wire.

     
         
  • Horsepower
     

    Measure of an engine's ability to perform work.

     
         
  • Hotchkiss Drive
     

    Open drive shaft that operates a rear axle assembly mounted on springs. The most common rear-wheel drive type.

     
         
  • Hot Idle Compensator
     

    Component that prevents stalling when engine temperature is high.

     
         
  • Hot Plug
     

    One with a long insulator tip, often used in older engines.

     
         
  • Hot Tank
     

    Cleaning tank with heated chemicals in which parts are immersed.

     
         
  • Hub
     

    Mounting place for vehicle wheel on end of axle or spindle.

     
         
  • Hybrid
     

    A vehicle using two different methods of propulsion, such as a small gasoline engine and an electric motor with batteries.

     
         
  • Hydraulic Actuator
     

    Solenoid-operated valve and electric pump mechanism.

     
         
  • Hydraulic Booster
     

    Braking system booster actuated by hydraulic pressure from the power steering pump.

     
         
  • Hydraulic Circuit Diagrams
     

    A schematic showing how transmission parts and passages interconnect.

     
         
  • Hydraulic Head
     

    The housing around a diesel injection pump plunger.

     
         
  • Hydraulic Lifter
     

    Oil-filled lifter that maintains zero valve clearance.

     
         
  • Hydraulic Press
     

    Machine used to exert pressure on parts that are being forced (press-fit) together.

     
         
  • Hydraulic System
     

    Arrangement of pistons and tubing that uses pressure to transmit force from one part to another.

     
         
  • Hydrocarbon
     

    Chemical mixtures (12 percent hydrogen, 82 percent carbon) making up crude oil, or petroleum.

     
         
  • Hydrometer
     

    Tool used to test for specific gravity indicating the condition of a batteries electrolyte and its ability to charge/hold a charge.

     
         
  • Hypoid Gears
     

    Gear arrangement with the pinion centerline well below the centerline of the ring gear.

     
         
  • I-CAR
     

    (Inter-Industry Conference on Auto Collision Repair) An international, non-profit training organization dedicated to improving the quality, safety and efficiency of auto collision repair for the benefit of the consumer. 800-422-7456
    Insurance Estimate: The preliminary assessment of damages and costs of repairs that will be used as a guideline for making repairs to the vehicle.

     
         
  • Idle
     

    The speed the engine runs when it is stopped and your foot is off the pedal.

     
         
  • Idle mixture
     

    The air-fuel mixture supplied to the engine whilst idling.

     
         
  • Ignition
     

    1. The key switch to start the engine with the ignition key.
    2. The start of combustion of the air-fuel mixture in the combustion chamber, in a petrol engine which is ignited by the high voltage spark.

     
         
  • Ignition Coil
     

    A transformer that steps up 12 volts into a high-voltage low-amperage spark to fire the cylinders.

     
         
  • Ignition Rotor
     

    A plastic device that sits inside the distributor cap, which directs the spark from the centre of the cap to the individualized cylinders.

     
         
  • Imbalance
     

    When 1 or more brakes operate before or after others, or with uneven brake pressure.

     
         
  • Induction
     

    The intake of air or air-fuel mixture into the engine.

     
         
  • Intake Air Temperature
     

    Sensor that monitors the temperature of the incoming air.

     
         
  • Intake manifold
     

    A cast series of channels that directs air and sometime fuel to the individual chambers.

     
         
  • Internal Combustion
     

    Burns inside. A type of engine that creates power by burning a fuel internally. Unlike externally as with a steam engine. Most cars on the road today use internal combustion engines, including those using petrol and diesel fuels.

     
         
  • Intuition
     

    Ability of a driver to respond to actions and reactions of other road users either consciously or unconsciously.

     
         
  • Inventory Management Systems (IMS)
     

    A method of recording and organizing all the parts available at a recycling facility. Usually provides descriptions such as yard location, quantity, years, make, model, condition, price and date of purchase. This system is computerized.

     
         
  • Idle Air Control Valve
     

    Solenoid operated valve in a Till system that regulates idle speed.

     
         
  • Idle Mixture Screw
     

    Adjusting device that meters fuel into the air horn.

     
         
  • Ignition Coil
     

    Device used to produce the high voltage needed for ignition spark.

     
         
  • Ignition Computer
     

    ECM that controls ignition timing, based on sensor input.

     
         
  • Ignition Distributor
     

    Component that directs coil voltage to each spark plug at the appropriate time.

     
         
  • Ignition Lag
     

    The time required for diesel fuel to vaporize, heat up, and begin to burn.

     
         
  • Ignition Spark Switch
     

    Used on some manual transmissions, this switch permits distributor vacuum advance in high gear.

     
         
  • Ignition System
     

    Components that produce a spark to ignite the air-fuel mixture in the engine.

     
         
  • Ignition Timing
     

    How early or late the spark plug fires in relation to the piston position.

     
         
  • I-Head
     

    One with intake and exhaust valves in the cylinder head.

     
         
  • IHP
     

    Indicated horsepower.

     
         
  • Impact Socket
     

    An attachment to an air-powered impact wrench.

     
         
  • Impeller
     

    Pump component with fan-like blades that spins inside a housing to move liquid.

     
         
  • Improper Injector Spray Pattern
     

    One that is restricted due to foreign matter in the injector.

     
         
  • In Board CV-Joint
     

    The inner universal joint on a front-wheel drive vehicle.

     
         
  • Incorrect Camber
     

    Condition that produces wear on one side of tire tread.

     
         
  • Incorrect Shift Points
     

    The transmission shifts too soon or too late in relation to engine speed.

     
         
  • Incorrect Toe
     

    Condition that produces a feathered edge on tire tread.

     
         
  • Independent Suspension
     

    System that permits each wheel to move up and down without seriously affecting any other wheel.

     
         
  • Inflation Pressure
     

    The amount of air pressure that a tire can safely handle.

     
         
  • Initial Ignition Timing
     

    Timing set with ignition idling.

     
         
  • Injection Pressure Tester
     

    A test device for precisely measuring diesel injection pressure.

     
         
  • Injection Pump
     

    A pump that meters fuel in a diesel system.

     
         
  • Injection Pump Test Stand
     

    Specialized testing equipment for use with injector pumps.

     
         
  • Injection Pump Timing
     

    Adjustment of the pump operation to match the engine's operating cycle.

     
         
  • Injection Timing
     

    The relationship between injection of fuel and the positions of the engines pistons.

     
         
  • Injector
     

    A spring-loaded valve that meters fuel into the pre-combustion chamber of a diesel engine.

     
         
  • Injector Leakage
     

    Dripping or spraying of fuel when the injector nozzle is closed.

     
         
  • Injector Opening Pressure
     

    Amount of pressure needed to open the injector nozzle.

     
         
  • Injector Output Volume
     

    The amount of fuel output over a specific time period.

     
         
  • Injector Rebuild
     

    A process involving cleaning, disassembly, replacement of worn parts, and the reassembly of a nozzle.

     
         
  • Injector Spray Pattern
     

    Shape of the spray produced by an injector.

     
         
  • Inlet Air Temperature Sensor
     

    The device that checks temperature of air entering the engine.

     
         
  • In-Line Engine
     

    One with cylinders lined up in a row.

     
         
  • In-Line Pump
     

    A diesel injection pump with one plunger (piston) for each cylinder.

     
         
  • Inner Stub Shaft
     

    Section of front-drive axle that is splined to differential gears. It is connected to the interconnecting shah through a universal joint.

     
         
  • Input
     

    The information provided to a computer by a sensor.

     
         
  • Input Shaft
     

    Metal shaft that transfers motion from the engine (via the clutch) to the transmission.

     
         
  • Instrumentation Computer
     

    One that uses sensor output to control dashboard displays.

     
         
  • Insulated Current Resistance Test
     

    Check of all parts between the battery positive and the starting motor for excess resistance.

     
         
  • Insulator
     

    A material that resists the flow of electrons.

     
         
  • Intake and Exhaust Ports
     

    Openings into the combustion chamber that are controlled by valves.

     
         
  • Intake Manifold
     

    Component that directs the air-fuel mixture from the carburetor or throttle body to the cylinders.

     
         
  • Intake Stroke
     

    Piston stroke that draws the air-fuel mixture into the cylinder.

     
         
  • Integral Power Steering
     

    A system in which the hydraulic piston is mounted inside the gearbox.

     
         
  • Integral Regulator
     

    A regulator that is mounted in or on an alternator.

     
         
  • Integral Valve Guide
     

    One machined into the cylinder head.

     
         
  • Integral Valve Seat
     

    One machined into the cylinder head.

     
         
  • Integrated Circuit
     

    A tiny "chip" of silicon containing complete electronic circuits.

     
         
  • Interconnecting Shaft
     

    Component of front-drive axle that connects inner and outer universal joints.

     
         
  • Interface
     

    Another name for a computer conditioner.

     
         
  • Interference Angle
     

    Slight difference in angle between valve face and valve seat for improved sealing when valve is closed.

     
         
  • Intermittent Problem
     

    One that occurs only under some conditions.

     
         
  • Internal Cam Ring
     

    A collar with lobes that operates diesel injectors.

     
         
  • Internal Oil Leakage
     

    Loss of oil by burning in the cylinders as a result of piston ring wear.

     
         
  • Jobber
     

    One who buys goods in quantity from manufactures or importers and sells them to dealers, middleman.

     
         
  • Jump Lead
     

    Each of a pair of heavy duty cables with powerful spring clamps at the ends, used to briefly supply power from a good battery to a flat battery

     
         
  • Jump Start
     

    To start the engine of a vehicle with a flat battery using a pair of jump leads and a good battery.

     
         
  • Jounce Bumper
     

    Rubber blocks that keep suspension parts from hitting the frame when the vehicle encounters large bumps or holes.

     
         
  • Journal Out-of-Roundness
     

    Greater wear on the top or bottom section of a crankshaft journal.

     
         
  • Journal Taper
     

    Difference in diameter of a crankshaft journal from one side to the other.

     
         
  • Jumper Cables
     

    Electrical cables used to start a car with a dead battery.

     
         
  • Jumper Wire
     

    A wire used to make a temporary electrical connections when testing electrical circuits.

     
         
  • Jumps Out of Gear
     

    A manual transmission problem in which the transmission will unexpectedly disengage and move into neutral.

     
         
  • Jump Starting
     

    Providing current to a car with a dead battery by connecting cables to the battery of an operating car.

     
         
  • Knock Pinking
     

    A noise caused by combustion occurring too quickly; also called ping or detonation.

     
         
  • KAM
     

    Keep-alive memory.

     
         
  • Key
     

    Metal piece that locks into a slot (keyway) to keep a part and a shaft turning together.

     
         
  • Kick-Down Valve
     

    Component that causes automatic transmission to shift down into a lower gear during fast acceleration.

     
         
  • Knock
     

    Engine noise caused by detonation.

     
         
  • Knock Sensor
     

    Engine sensor that detects detonation in the engine.

     
         
  • kV
     

    Kilovolt (1000 volts).

     
         
  • Late Model Vehicles
     

    A recent production. For example late model vehicles would be vehicles produced within the past 5 years.

     
         
  • Liquid Cooled Engine
     

    An engine wherein the excess heat is removed by circulation of a water based fluid through hot areas to a heat exchanger and return.

     
         
  • LKQ Parts
     

    Like kind and quality. Describes replacement parts that are of the same quality as the original prior to an accident.
    LKQ parts can be new, OEM replacement or recycled parts.

     
         
  • Dipstick
     

    A calibrated measuring rod for checking the level of fluids, e.g. oil

     
         
  • Lubrication Service
     

    An engine oil and filter change only.

     
         
  • Lapping Valves
     

    A polishing operation with a fine grin ding compound that helps smooth the mating surfaces of valve faces and valve seats.

     
         
  • Lateral Run-Out
     

    Side-to-side movement of a wheel or tire.

     
         
  • Leaded Gasoline
     

    Fuel with an antiknock additive. Leaf spring Flat pieces of spring steel that are stacked and bound together. Normally used as part of a vehicle's rear suspension.

     
         
  • Leak Detector
     

    Device used to locate refrigerant leaks in a system.

     
         
  • Leaking Exhaust Manifold Gasket
     

    Creates metal-like rapping sound.

     
         
  • Leaking Heater Core
     

    Rusted or cracked tube in core, allowing coolant to escape.

     
         
  • Leaking Injector
     

    One that allows extra fuel to drip out, causing a richer mixture.

     
         
  • Leaking Intake Manifold Gasket
     

    Possible case of vacuum leak resulting in rough idle.

     
         
  • Leaking Valve Seal
     

    A condition that allows oil to be drawn into intake or exhaust port and burned causing blue smoke.

     
         
  • Lean Air-Fuel Ratio
     

    An air-fuel mixture that contains more air than a stoichio metric mixture.

     
         
  • Led Code
     

    Trouble code displayed as a pattern of lighted code.

     
         
  • L-Head
     

    One with both the intake arid exhaust valves ii~ the block.

     
         
  • Lift
     

    See Grease Rack.

     
         
  • Lifter Leak-Down Rate
     

    Time required for a hydraulic lifter plunger lobe pushed to the bottom of its stroke under cent roiled conditions.

     
         
  • Lifting Fixture or Chain
     

    Device fastened to an engine to allow it to be lifted by a crane or hoist.

     
         
  • Limited Slip Differential
     

    One that provides a driving force to both real wheels at all times.

     
         
  • Limited Slip Differential Chatter
     

    Sound made when turning a corner, caused by sticking and releasing of clutches in the differential.

     
         
  • Line Bore
     

    A machining operation resulting in a carefully aligned series of holes through an engine block for the crankshaft bearings.

     
         
  • Liner
     

    A thin rubber layer bonded to plies and forming the inside surface of the tire.

     
         
  • Line Wrench
     

    Special wrench with split jaw that can be slipped over tubing (such as a fuel line) to tighten or loosen compression fittings.

     
         
  • Liquid-Vapor Separator
     

    Tank that permits liquid fuel to settle out and flow back to fuel tank.

     
         
  • Liquid Cooling System
     

    Circulation of a heat-absorbing medium through engine passages, with the accumulated heat dissipated by further circulation through heat exchanger (radiator).

     
         
  • Load or Acceleration Test
     

    Oscilloscope reading that measures the firing voltages of the spark plugs when the engine is accelerating rapidly.

     
         
  • Load Rating
     

    The maximum amount of weight a tire can carry when inflated to the recommended pressure.

     
         
  • Locked-in Gear
     

    A manual transmission problem often caused by damaged or sticking linkage. Broken gear teeth can also be at fault.

     
         
  • Locking Hub
     

    Components that transfer power from driving axles to driving wheels on a four-wheel-drive vehicle.

     
         
  • Lock-up Converter
     

    A variation of the fluid coupling, with an internal friction clutch mechanism. It 'locks up" in high gear, improving fuel economy.

     
         
  • Longitudinal
     

    Lengthwise; term used to identify an engine mounted with its centerline on or parallel to the centerline of the vehicle.

     
         
  • Low Brake Pedal
     

    Farther than normal brake pedal travel before braking begins.

     
         
  • Low Pressure Cutout Switch
     

    One that pre\ cuts compressor operation and possible damage if air conditioning system pressure drops below a set point.

     
         
  • Low Side
     

    Section of an air conditioning system in which refrigerant is under high pressure.

     
         
  • LPG
     

    Liquefied petroleum gas, an alternate fuel.

     
         
  • Lubrication Service
     

    The process of checking and adjusting the levels of all lubricants in a vehicle.

     
         
  • Lubrication System
     

    Method of distributing lubricant (oil) to moving parts to minimize friction.

     
         
  • Lug Nut
     

    Large steel nuts used to hold a wheel into the axle hub.

     
         
  • Lug Stud
     

    Special bolts that are press-fit into the axle hub and accept lug nuts to mount the vehicle's wheels.

     
         
  • Manifold
     

    A fitting on an internal- combustion engine that receives the exhaust gases from several cylinders.

     
         
  • Manual Transmission
     

    Manual selection of each gear, usually requiring manual operation of a clutch.

     
         
  • Mass Airflow Meter
     

    A device which measures air- flow into an engine and continuously sends a signal to the computer.

     
         
  • Master Cylinder
     

    Hydraulic control device that converts the force from the driver’s foot to hydraulic force in the brake system.

     
         
  • Misfire
     

    Failure to cause the mixture in the combustion chamber to burn.

     
         
  • MacPherson Strut
     

    Suspension system that uses one control arm and one strut for each wheel assembly.

     
         
  • Magna fluxing
     

    Testing procedure that uses a magnet and metal powder to find cracks in cast iron parts.

     
         
  • Magnetic Clutch
     

    Device used to engage and disengage the compressor of an air conditioning system.

     
         
  • Magnetic Field
     

    Field of force generated around an electrical conductor.

     
         
  • Magnetic Sensor
     

    One that uses part movement (such as rotation) and induced current to produce a signal for a computer.

     
         
  • Mag-Tach
     

    A magnetically triggered tachometer usable on both gasoline and diesel engine.

     
         
  • Main Bearing Bores
     

    Holes machined into the bottom of the block for the crankshaft and its bearings.

     
         
  • Main Bearing Cap Torque
     

    The factory recommended degree of tightness for main cap bolts.

     
         
  • Main Bearing Knock
     

    Deep, resonant sound caused by wear of bearing and possibly crankshaft journal.

     
         
  • Main Body
     

    Central portion of the carburetor, forming the air horn and fuel bowl.

     
         
  • Main Caps
     

    Pieces the bolt to the bottom of the block to hold the crankshaft in place.

     
         
  • Main Computer
     

    The largest and most powerful microprocessor in a vehicle's system. It can control other computers.

     
         
  • Main Discharge Tube
     

    Passage between fuel bowl and venturi.

     
         
  • Mainframe Computer
     

    A large, centralized computer with a great deal of memory and computing power.

     
         
  • Main Jet
     

    Fuel inlet metering device for normal-speed engine operation.

     
         
  • Main Journals
     

    Carefully machined surfaces on the ends of the crankshaft that fit into the block main bearings.

     
         
  • Maintenance-Free Battery
     

    One without removable filler caps that does not require periodic filling with water.

     
         
  • Maintenance Interval
     

    The specific number of miles or months that should elapse between tune-ups as described in the vehicle owner's manual.

     
         
  • Main Thrust Bearing
     

    Flanged version of main bearing, designed to limit crankshaft endplay.

     
         
  • Major Tune-Up
     

    A tune-up requiring some decree of repair to systems, in addition to the work done for a minor tune-up.

     
         
  • Manifold Pressure Sensor
     

    Measures pressure inside the intake manifold. Also called MAP sensor.

     
         
  • Manual Bleeding
     

    A method of system bleeding using only master cylinder pressure.

     
         
  • Manual Transaxle
     

    One with a manual (driver-operated) transmission.

     
         
  • Manual Transmission
     

    One that is shifted from gear to gear by the vehicle operator.

     
         
  • Manual Valve
     

    In an automatic transmissions a valve actuated by the gear shift lever that routes oil pressure to the components required for the selected gear.

     
         
  • Manufacturer's Manual
     

    Service manual produced by an auto maker and restricted to its vehicles.

     
         
  • Master Cylinder
     

    Hydraulic piston type pump that develops pressure for the braking system.

     
         
  • Mechanical Choke Unloader
     

    A linkage that opens the choke plate whenever the throttle swings fully open.

     
         
  • Mechanical Efficiency
     

    A comparison of brake horsepower to indicated horsepower, measuring frictional loss.

     
         
  • Mechanical Fuel Pump
     

    A Device that uses a reciprocating motion to move fuel.

     
         
  • Mechanical Lifter
     

    Solid lifters that must be adjusted periodically.

     
         
  • Metering Rod
     

    Stepped rod that moves in and out of main jets to alter fuel flow.

     
         
  • Metering Valve
     

    Valve designed to equalize pressure at wheel cylinders on vehicles with front disc and rear drum brakes. Is also known as a Proportioning Valve.

     
         
  • Methyl Alcohol
     

    Wood alcohol, or methanol.

     
         
  • Metric Measuring System
     

    System of measure, based on units of 10, that is used by most of the world.

     
         
  • Mica
     

    Mineral used as an insulator between commentator segments.

     
         
  • Micrometer
     

    A precision measuring device for very small distances.

     
         
  • Microprocessor
     

    A small computer, sometimes called a "chip" or "IC" (integrated circuit).

     
         
  • Milky Fluid
     

    Condition caused by contamination of transmission fluid by engine coolant.

     
         
  • Milky or White Oil
     

    Lubricant that has become contaminated by the presence of coolant.

     
         
  • Milling
     

    A machining process that removes a thin layer of metal; often used to repair warped engine cylinder heads.

     
         
  • Millisecond
     

    Fraction (1000th) of a second.

     
         
  • Minimum Disc Thickness
     

    Thinnest rotor dimension allowed for proper and safe operation of disc brakes.

     
         
  • Minor Tune-Up
     

    A tune-up done on an engine in good condition, involving primarily adjustment and ignition parts replacement or maintenance.

     
         
  • Missing
     

    Failure of one or more cylinders to fire.

     
         
  • Mixture Control Solenoid
     

    Electromechanical; device that opens and closes air and fuel passages in carburetor.

     
         
  • Modem
     

    A modulator-demodulator; a device that changes analog signals to digital, and vice versa, for communications.

     
         
  • Modem Analyzer System
     

    System that allows a shop computer analyzer to communicate via telephone line with a large mainframe that stores information needed for advanced troubleshooting.

     
         
  • Modulated Injection
     

    Injection of fuel intermittently, without reference to intake valve timing.

     
         
  • Modulator Vacuum Leakage
     

    Cause of incorrect shift point operation in an automatic transmission.

     
         
  • Movable Pole Shoe
     

    Device that uses a yoke lever to move the pinion gear into contact with the flywheel gear.

     
         
  • Muffler
     

    An exhaust-system component that decreases the noise of vehicle operation.

     
         
  • Muffler Clamps
     

    U-shaped connectors for fastening parts of the exhaust system together.

     
         
  • Multi-Cylinder Engine
     

    One that has two or more cylinders.

     
         
  • Multi-Point
     

    Fuel injection system that sprays fuel into port for each cylinder.

     
         
  • Multi-Weight
     

    Motor oil that exhibits different viscosity characteristics under different conditions.

     
         
  • Multi-Meter
     

    An electrical test device that can be used to measure voltage, current, or resistance.

     
         
  • Multiple Disc Clutch
     

    One with several discs that can be used to drive planetary gear sets.

     
         
  • Mushroomed Valve Stem
     

    Stem end that had been enlarged and spread outward by rocker arm contact.

     
         
  • Mushy Shifts
     

    Transmission changes gears too slowly.

     
         
  • Neutral Safety Switch
     

    Switch that prevents the starter from operating in any transmission range except park or neutral.

     
         
  • Needle Valve
     

    A precisely machined rod used to control fuel flow from in the injector.

     
         
  • Net hp
     

    Maximum horsepower developed with all accessories in use.

     
         
  • Neutral Safety Switch
     

    Switch that prevents engaging the starter when the vehicle is in gear.

     
         
  • Neutral Safety Switch Adjustment
     

    Altering position of the switch to permit starting of the engine when gear selector is in the "park" position.

     
         
  • NIASE
     

    National Institute for Automotive Service Excellence.

     
         
  • Noise Suppressor
     

    Capacitors that absorb voltage fluctuations in a car's electrical system, reducing radio noise.

     
         
  • Nonadjustable Rocker Arm
     

    One that does not allow clearance to be changed. Used with hydraulic lifters.

     
         
  • Non-Driving Hub
     

    One that rotates freely on spindles (axle ends).

     
         
  • Non-Independent Suspension
     

    System in which wheels are attached to each end of a solid axle.

     
         
  • Normal Aspiration
     

    System that provides air to the engine at normal atmospheric pressure.

     
         
  • No Start Problem
     

    Engine turns over but refuses to fire.

     
         
  • NOx
     

    Abbreviation for oxides of nitrogen, pollutants resulting from high combustion temperatures.

     
         
  • Number Set
     

    Punches used to indent identifying numbers in metal.

     
         
  • Nut Lock
     

    Thin, slotted nut that fits over main spindle nut on a nondriving wheel.

     
         
  • Octane
     

    A petrol rating of how quickly the fuel burns. The higher the rating, the slower and more controlled the fuel burns. This allows its use in high compression engines.

     
         
  • Odometer
     

    Device on the instrument panel to measure the total miles traveled in the course of the life of the vehicle.

     
         
  • OEM
     

    Original Equipment Manufacturer. Refers to parts that are made by the vehicle’s manufacturer such as Ford or Honda, either new or recycled

     
         
  • Oil
     

    A lubricant made from crude oil used for lubrication between moving parts and for cooling.

     
         
  • Oil Filter
     

    A device, with a typically with a filter size of 10 microns, which strains dirt and particles out of the engine oil.

     
         
  • Oil Pump
     

    A device that forces engine oil through the engine to lubricate the moving parts.

     
         
  • Oxygen Sensor
     

    Indicates the level unburned fuel in the exhaust so the computer can adjust the air- fuel level.

     
         
  • O2 Readings
     

    Oxygen must be present for proper catalytic converter functioning. Analyzers measure it in percentage by volume.

     
         
  • Octane Number
     

    Indicators of the antiknock value of a gasoline.

     
         
  • OHC Follower
     

    Component that fits between camshaft and lifter.

     
         
  • Ohm's Law
     

    A simple formula for computing unknown electrical values when two values are known.

     
         
  • Oil Change Interval
     

    Mileage or period of time after which oil should be changed (3000 miles or three months, typically).

     
         
  • Oil Consumption
     

    The loss of oil caused by internal or external leakage.

     
         
  • Oil Cooler
     

    A radiator-like device used to regulate oil temperature.

     
         
  • Oil Dye
     

    Additive used to help locate leaks.

     
         
  • Oil Filler Cap
     

    A metal or plastic cap used to cover the opening on an engine where oil is added.

     
         
  • Oil Film
     

    Thin layer of lubricant between parts, preventing metal-to-metal contact.

     
         
  • Oil Filter Housing
     

    Part of the engine on which the filter is mounted.

     
         
  • Oil Gallery
     

    Passage in the engine block through which oil can flow to point requiring lubrication.

     
         
  • Oil Pressure Gauge
     

    Instrument that provides a direct reading of engine oil pressure.

     
         
  • Oil Pressure Indicator
     

    Warning light on control panel to alert driver to low pressure conditions.

     
         
  • Oil Pressure Switch
     

    Safety device that shuts off the fuel pump if engine oil pressure drops.

     
         
  • Oil Pressure Test
     

    Measurement of actual oil pressure using a special testing device.

     
         
  • Oil Pump
     

    Device for forcing oil under pressure to the points where lubrication is needed.

     
         
  • Oil Ring
     

    Piston ring that scrapes excess oil off the cylinder wall.

     
         
  • Oil Service Rating
     

    Identification of type of service for which an oil is suited.

     
         
  • Oil Slinger
     

    Washer-shaped part mounted on crankshaft sprocket to throw oil onto timing chain during operation.

     
         
  • Oil Spurt Hole
     

    Small hole drilled in connecting rod for improved cylinder lubrication.

     
         
  • Oil Streaked Sight Glass
     

    A sign that the air conditioning system is low on refrigerant and allowing excess oil to circulate.

     
         
  • One-Wire Circuit
     

    One that uses the vehicle frame as a return wire to the power source.

     
         
  • Open Circuit
     

    Electrical circuit with a gap or break in continuity so that current cannot flow.

     
         
  • Open End
     

    A type of wrench with an open jaw on both ends.

     
         
  • Open Injector Coil
     

    A broken wire in the solenoid coil is preventing operation.

     
         
  • Open Loop
     

    Control system using preset values in the computer to operate engine.

     
         
  • Open System
     

    Cooling system that does not use a recovery tank.

     
         
  • Operating Parameter
     

    An acceptable maximum or minimum electrical value.

     
         
  • Opposed Engine
     

    One with cylinders lying flat on either side of the crankshaft.

     
         
  • Organizing Tray
     

    Tray or board with holes in it for holding push rods and lifters during engine disassembly.

     
         
  • O-Ring Seal
     

    A synthetic rubber ring that fits into a groove and is compressed when parts are assembled.

     
         
  • O-Ring Valve Seal
     

    Small round ring, usually of rubber, that fits in a groove on a shaft to prevent oil leakage.

     
         
  • Oscilloscope
     

    Instrument that displays line patterns that relate voltages to time.

     
         
  • Outboard CV-Joint
     

    The outer universal joint on a front-wheel drive vehicle.

     
         
  • Outer Stub Shaft
     

    In a front-wheel drive vehicle, the short shaft connecting outer universal joint and the front wheel hub.

     
         
  • Output
     

    The signal sent by a computer (for example, to an actuator) as a result of processing inputs it has received.

     
         
  • Output Shaft
     

    Transmission shaft on which the out-put gears are mounted.

     
         
  • Output Shaft Gears
     

    Gears that turn the output shaft of a manual transmission.

     
         
  • Overbore Limit
     

    The largest possible diameter to which a cylinder can be bored without weakening its walls.

     
         
  • Overdrive Ratio
     

    The situation in which a large gear is used to drive a smaller gear, with an increase in speed as a result.

     
         
  • Overhead Valve
     

    One located in the cylinder head, rather than the block.

     
         
  • Over Inflation
     

    Operating tire with a higher-than-recommended air pressure.

     
         
  • Overrunning Clutch
     

    Device that locks a pinion gear in one direction and releases it in the other.

     
         
  • Oversize Piston and Rings
     

    Larger components sized to fit a re-bored cylinder.

     
         
  • Oxygen Sensor
     

    Device that monitors oxygen content in engine exhaust to correct air-fuel ratio.

     
         
  • Parts Car
     

    Vehicles that are purchased and dismantled for the recovery of reusable parts

     
         
  • Piston
     

    A round cup that slides through the cylinders to create the flow of air through the engine and transfer the energy of combustion to the crankshaft.

     
         
  • Positraction
     

    A type of differential that limits the difference in speed between the right and left wheel. This helps prevent the car from spinning its wheels and getting stuck on ice or snow.

     
         
  • Powertrain Control Module Electronic controller
     

    The computer that controls engine and transmission operation.

     
         
  • Pre-dismantling
     

    The step prior to taking the parts off the car. At this stage, the dismantler identifies those parts that are in demand and orders that they be taken off the car for inventory.

     
         
  • Pre-Loss Condition
     

    Overall condition of vehicle immediately preceding collision, vandalism or theft.

     
         
  • Pressure Regulator
     

    A governor which controls the pressure of the fuel delivered to the injectors.

     
         
  • Production Date
     

    The month and year that a vehicle was produced. This date is often located on the driver’s side door post of the vehicle.

     
         
  • Propylene glycol
     

    Chemical name for environmentally safe coolant.

     
         
  • Packing Wheel Bearings
     

    Filling the bearing shells with grease to prevent excessive wear.

     
         
  • Pad Wear Sensor
     

    Metal tab on brake pad that makes a squealing noise to signal the need for pad replacement.

     
         
  • Pancake Chamber
     

    Combustion chamber that forms a flat pocket over the piston.

     
         
  • Parade Pattern
     

    Oscilloscope pattern that shows traces for each cylinder from left to right across the screen.

     
         
  • Parking Pawl
     

    A latch that locks the transmission so that the vehicle will not roll when the selection lever is in the "Park" position.

     
         
  • Part Alignment Marks
     

    Lines or other marks scribed on parts by a technician during disassembly, so that components can be reassembled properly.

     
         
  • Particulates
     

    Solid particles of soot and other substances that result from combustion.

     
         
  • Part Warpage
     

    Often causes gasket failure, since parts do not seal together properly.

     
         
  • Passive Sensor
     

    One that changes an externally produced signal, but does not generate its own voltage.

     
         
  • PCV System
     

    Positive crankcase ventilation, a system that decreases pollution by drawing toxic gases back through the combustion process.

     
         
  • Pedal Free Play
     

    The amount of brake pedal movement before braking action begins to take place.

     
         
  • Pedal Height
     

    Distance of brake pedal above floor of vehicle.

     
         
  • Performance Test
     

    A measurement of air conditioning system performance made with the vehicle engine running.

     
         
  • Petroleum
     

    Oil taken directly out of the ground.

     
         
  • Pickup Coil
     

    Component that sends pulses to the control unit of an electronic ignition system as a result of trigger wheel rotation.

     
         
  • Pickup Coil Air Gap
     

    Space between the pickup coil and trigger wheel tooth.

     
         
  • Pilot Bearing
     

    The bushing or bearing that supports the forward end of the transmission input shaft.

     
         
  • Ping
     

    A mild knock (light tapping noise) caused by pre-ignition of fuel.

     
         
  • Pinion Gear
     

    Differential gear turned by the driveline. It meshes with the ring gear. Also, gearbox component that meshes with rack, or a small gear on a starter motor that engages a larger gear to rotate the engine flywheel.

     
         
  • Pinion Gear Bearing Preload
     

    Degree of tightness of bearings, adjusted by compressing a spacer or using shims.

     
         
  • Pinion Gear Clearance
     

    Distance between the pinion gear and drive end frame when gear is engaged.

     
         
  • Pinion Gear Depth
     

    The distance the pinion gear extends into the carrier to mesh with the ring gear.

     
         
  • Pinion Pilot Bearing
     

    A bearing used to support the pinion gear in the differential.

     
         
  • Pinion Shaft
     

    Shaft holding the two differential idler (pinion) gears.

     
         
  • Pinpoint Tests
     

    Specific tests of individual components of a vehicle, using the electronic scanner.

     
         
  • Pintle
     

    An inward-opening diesel injector nozzle, with fuel flow controlled by a pintle (needle tip).

     
         
  • Pipe Expander
     

    Tool used to slightly enlarge inner diameter of steel exhaust pipes to make assembly easier.

     
         
  • Pipe Shaper
     

    Tool used to remove dents from pipe ends.

     
         
  • Piston
     

    Component that rides up and down in the cylinder.

     
         
  • Piston and Rod Markings
     

    Identifying marks on pistons and connecting rods to aid in proper assembly.

     
         
  • Piston Clearance
     

    Difference between cylinder bore and piston diameter.

     
         
  • Piston Knurling
     

    A technique in which the piston skirt is grooved, pushing up metal a few thousandths of an inch to slightly increase piston diameter.

     
         
  • Piston Pin
     

    Fastening device that holds piston onto the connecting rod.

     
         
  • Piston Pin Knock
     

    Double knock caused by excessive clearance between pin and connecting rod bushing.

     
         
  • Piston Pin Offset
     

    Positioning of the piston pinhole slightly off the piston centerline for quieter operation.

     
         
  • Piston Ring Gap
     

    Clearance between ends of rings when installed on cylinder.

     
         
  • Piston Size
     

    Diameter of the piston, measured on the skirt.

     
         
  • Piston Slap or Knock
     

    A loud metallic sound caused by excessive wear to piston skirt or cylinder.

     
         
  • Piston Stroke
     

    The distance the piston moves from BDC to TDC.

     
         
  • Piston Taper
     

    A slight top-to-bottom difference in piston diameter to adjust for differences in expansion rates.

     
         
  • Pitch Line
     

    Imaginary line along the center of a gear tooth.

     
         
  • Pitman Arm
     

    Component that transfers gearbox motion to the steering linkage.

     
         
  • Pitman Shaft Over-Center Adjustment
     

    Adjustment of clearance between sector gear and ballnut teeth in re-circulating ball gearbox.

     
         
  • Planetary Gear Set
     

    A set of gears consisting of several "planet" gears rotating around a central "sun" gear.

     
         
  • Plastigage
     

    A plastic measuring clearance tool that is compressed between bearing surfaces, then compared to a scale to find thickness.

     
         
  • Plate
     

    A grid, covered with porous lead, that will store electrical energy.

     
         
  • Pleated Paper Filter
     

    An in-line fuel filter.

     
         
  • Plug Gap
     

    Distance between the center and side electrodes on a spark plug.

     
         
  • Plug Heat Range
     

    Numeric indicator of how hot a spark the plug will develop.

     
         
  • Plug Reach
     

    Length of the threaded portion of a spark plug.

     
         
  • Ply Separation
     

    Pulling apart of tire plies as a result of overheating due to under inflation, or other causes.

     
         
  • Pneumatic
     

    Filled with air.

     
         
  • POA
     

    Pilot operated absolute valve.

     
         
  • Pole Piece
     

    Magnetic component of motor that keeps the armature rotating.

     
         
  • Poor Fuel Economy
     

    High fuel usage caused by such conditions as overly rich air-fuel mixture or incorrect engine timing.

     
         
  • Pop Tester
     

    Unit used to test diesel injectors when they are out of the engine.

     
         
  • Port Injection
     

    Another name for multi-point injection.

     
         
  • Potentiometer Sensor
     

    One that changes resistance in response to external change (such as part movement).

     
         
  • Power
     

    The rate or speed at which work is done.

     
         
  • Power Antenna
     

    A radio antenna equipped with a small electric motor for raising and lowering.

     
         
  • Power Brush
     

    Cleaning tool used with an electric or air-driven drill.

     
         
  • Power Door Lock
     

    One that is opened or closed with a solenoid.

     
         
  • Power Steering Fluid
     

    A hydraulic oil usually automatic transmission fluid.

     
         
  • Power Steering Pressure Test
     

    Use of a pressure gauge to check pump and associated component for correct pressure.

     
         
  • Power Steering Pump
     

    The unit that provides the hydraulic pressure needed in a power steering system.

     
         
  • Power Stroke
     

    The stroke in which the piston is driven downward by the explosion of the air-fuel mixture in the cylinder.

     
         
  • Power Train
     

    Gearing system and other components used to transfer energy from the engine to the vehicle's wheels.

     
         
  • Power Valve
     

    A device that performs the same function as a metering rod.

     
         
  • Power Window
     

    One that is raised and lowered through use of a small electric motor.

     
         
  • Pre-Chamber Cup
     

    Pressed in combustion area equipped with a glow plug for easier w inter starting of a diesel engine.

     
         
  • Pre-Combustion Chamber
     

    Used in diesel engines with a glow plug for easier winter starting.

     
         
  • Pre-Ignition
     

    Ignition of fuel before it is fully compressed in the cylinder.

     
         
  • Pre-Lubricator
     

    Pressure tank used to force oil through a lubrication system without running the engine, as a means of testing for worn engine bearings.

     
         
  • Press-Fit Piston Pin
     

    One forced into the connecting rod end. The piston can move freely, however.

     
         
  • Pressed-in Valve Guide
     

    One that uses a sleeve pressed into a hole machined in the cylinder head.

     
         
  • Pressure Bleeding
     

    A method of system bleeding using additional pressure supplied by an external air tank.

     
         
  • Pressure Cap Test
     

    Measurement of the opening pressure of a radiator cap.

     
         
  • Pressure Chamber
     

    Area around the needle valve of an injector where pressure builds up to open valve.

     
         
  • Pressure Fed Oiling
     

    Oil provided to high-friction areas by means of a pump.

     
         
  • Pressure Gauge
     

    Test instrument used to read positive pressure values.

     
         
  • Pressure Gauge or Manifold Assembly
     

    A combination of pressure gauges, valves, and hoses used to check air conditioning system pressures and remove or add refrigerant.

     
         
  • Pressure Plate
     

    Spring-loaded device that clamps clutch disc against flywheel.

     
         
  • Edit text
  • Pressure Plate Covers
     

    Lid that bolts on the pressure plate to hold various components in place.

     
         
  • Pressure Plate Face
     

    A large ring that contacts the friction disk as the clutch engages.

     
         
  • Pressure Plate Release Levers
     

    Levers hinged inside the pressure plate that help move the pressure plate face away from the clutch disk and flywheel.

     
         
  • Pressure Regulator
     

    A limiting device in an automatic transmission, regulating maximum hydraulic oil pressure.

     
         
  • Pressure Relief Valve
     

    Spring-loaded bypass that operates when pressure reaches a preset point.

     
         
  • Pressure Tests
     

    Diagnostic test using gauge to check fluid pressures in various transmission hydraulic circuits.

     
         
  • Pressure Valve
     

    Spring-loaded disc inside radiator cap that opens when system pressure increases past its set-point.

     
         
  • Primary
     

    In a carburetor, the components that operate under normal driving conditions.

     
         
  • Primary and Secondary Pistons
     

    The two pistons in a brake system dual master cylinder.

     
         
  • Primary and Secondary Shoes
     

    Front and back shoes in a drum brake system. The secondary shoe has a larger surface area.

     
         
  • Primary Circuit
     

    In an ignition system, all components operating on battery (low) voltage.

     
         
  • Primary Pattern
     

    Pattern of low-voltage (ignition primary) changes, as shown on an oscilloscope.

     
         
  • Primary Wire
     

    Small insulated conductor that carries battery or alternator voltage.

     
         
  • Printed Circuit
     

    One that consists of conductors that are flat metallic strips applied to an insulating board base. Other components are mounted on the board, as well.

     
         
  • Printer
     

    A device attached to an engine analyzer that can print out a "hard copy" of test results.

     
         
  • Probe Tools
     

    Used to view or retrieve items in hard-to-reach areas. Mirrors and magnetic pickups are examples.

     
         
  • Process
     

    The action taken by a computer program as a result of information from inputs.

     
         
  • Programmed
     

    Provided with a specific set of directions for actions to be taken.

     
         
  • PROM
     

    Programmable read-only memory.

     
         
  • PROM Carrier
     

    A plastic case used to protect a PROM making installation easier.

     
         
  • Proportioning Valve
     

    Valve designed to equalize pressure at wheel cylinders on vehicles with front disc and rear drum brakes.

     
         
  • Pulling Brakes
     

    Situation in which car veers to one side when brakes are applied.

     
         
  • Pulse Air System
     

    System that produces the same results as an air injection system, but uses natural pressure pulses in the exhaust system to provide airflow.

     
         
  • Pulse Ring
     

    A trigger wheel placed on the crankshaft damper in a crankshaft triggered ignition system.

     
         
  • Pulse Width
     

    An indication of how long an injector is energized and kept open.

     
         
  • Pumping Plunger
     

    Small pistons used to pump and pressurize diesel fuel.

     
         
  • Purge Line
     

    Line connecting the charcoal canister and engine intake manifold.

     
         
  • Push Rod
     

    When camshaft is located in block. the long push-rod transmits motion from lifter to rocker arm.

     
         
  • Quickstart
     

    An easily ignited ether based fuel, dispensed from an aerosol into the air intake to assist a cold engine in starting, especially for diesel engines.

     
         
  • Quick Charge Test
     

    A method of determining whether battery plates are sulfated (no longer able to hold a charge).

     
         
  • Racking
     

    Steel structures used to shelve and categorize all parts in warehouse

     
         
  • Radiator
     

    A series of vanes and fins that conducts heat from the coolant and allows outside air to carry it away.

     
         
  • Rebuildables
     

    Vehicles that can be repaired

     
         
  • Rebuilder
     

    An individual who rebuilds a vehicle

     
         
  • Recycled OEM Parts
     

    Quality OEM Parts removed from Total Loss Vehicles or ELV’s and sold to replace damaged parts in running vehicles.

     
         
  • Recycled Parts
     

    Parts removed from a damaged vehicle and cleaned or reconditioned to be sold to replace parts on another, running vehicle damaged in an accident.

     
         
  • Refrigerant
     

    Chemical used to transfer heat by taking advantage of the laws of physics.

     
         
  • Regulator
     

    Device which automatically controls pressure, temperature voltage, current, fluid, flow.

     
         
  • Remanufactured Parts
     

    Used hard parts that have been reconditioned to the same quality as new

     
         
  • Repairable
     

    A vehicle that can be fixed (repaired)

     
         
  • Replacements part
     

    Any part, new, used or aftermarket that replaces the damaged item on a vehicle.

     
         
  • R-12 Frostbite
     

    Injury resulting from contact with extremely cold refrigerant

     
         
  • Rack
     

    Flat toothed bar that is moved left or right by rotation of pinion gear.

     
         
  • Rack and Pinion Steering Gear Adjustment
     

    Tightening or loosening rack adjustment screws as necessary for optimum steering.

     
         
  • Radial Run out
     

    Uneven rotation caused by differences in diameter.

     
         
  • Radial Tire
     

    A tire that has horizontal material cords (stripes) from the inside tire wall to the outside tire wall with the tire tread molded on top.

     
         
  • Radiation
     

    The method of heat transfer through infrared radiation.

     
         
  • Radiation Interference
     

    Unwanted voltage that can cause a computer to malfunction.

     
         
  • Radiator
     

    An arrangement of tubes and cooling fins that serves as a heat exchanger on a vehicle.

     
         
  • Radiator Cap
     

    Closure that seals and pressurizes the cooling system of a vehicle.

     
         
  • Radiator Hoses
     

    Flexible tubes that carry coolant between the engine and radiator.

     
         
  • Radiator Shop
     

    Specialized repair facility for radiators.

     
         
  • Radio
     

    The receiving unit for broadcast AM or FM signals.

     
         
  • Radio Noise
     

    Static or interference that interferes with signal reception.

     
         
  • RAM
     

    Random access memory.

     
         
  • Raster Pattern
     

    Oscilloscope pattern that shows the traces for the cylinders stacked vertically, bottom to top.

     
         
  • Reading Oxygen Sensor Tip
     

    A visual inspection of tip color, which indicates engine condition.

     
         
  • Reading Spark Plugs
     

    Determining cause of a problem by examining condition of the spark plug.

     
         
  • Reading Tires
     

    Identifying alignment, suspension, and other problems through the wear patterns on tire treads.

     
         
  • Reading Trouble Code
     

    Identifying the code number for the indicated condition from any of the various display systems.

     
         
  • Reaming
     

    Process of cutting valve guide to slightly larger diameter. Valves with oversize stems can then be installed.

     
         
  • Rear Axle Assembly
     

    A combination of gears and axles converting rotary motion of the drive shaft to forward or backward motion of the vehicle.

     
         
  • Rear Axle Ratio
     

    The relationship between the numbers of teeth on the pinion gear and ring gear. Ratio affects acceleration, pulling power, and fuel economy.

     
         
  • Rear Drive Axle Assembly
     

    Differential, axles, and other components transferring power from drive line to rear wheels.

     
         
  • Rear Drive Axles
     

    The components that transmit power from the differential gears to the wheels.

     
         
  • Rear Main Oil Seal
     

    Seal that fits around the rear of the crankshaft to prevent oil leakage.

     
         
  • Rear Wheel Bearing
     

    Ball or roller-type bearings that reduce friction between the axle and axle housing.

     
         
  • Receiver-Drier
     

    Air conditioning system component that removes moisture and stores extra refrigerant.

     
         
  • Re-Circulating Ball
     

    Most common type of gearbox used with linkage steering system.

     
         
  • Rectified
     

    Term used to describe AC current that has been changed to DC.

     
         
  • Reduction Starter
     

    One that uses extra gears to increase the torque applied to the flywheel gear.

     
         
  • Reference Voltage
     

    A known voltage (usually 0.5 V) fed to passive sensors by a computer. Changes in sensor resistance can then be read by the computer.

     
         
  • Refract meter
     

    Test instrument used to measure antifreeze protection.

     
         
  • Refrigerant
     

    Substance with a very low boiling point that can be used to absorb heat.

     
         
  • Refrigerant Oil
     

    Lubricant used in the compressor of an air conditioning system.

     
         
  • Regulator Bypass Test
     

    Test that connects full battery voltage to the alternator field, leaving the regulator out of the circuit.

     
         
  • Regulator Voltage Test
     

    Test of the charging system under low output, low load conditions.

     
         
  • Relay
     

    Electrically operated switch.

     
         
  • Relay Actuator
     

    One that uses a smaller current flow to operate a switch controlling a larger current flow.

     
         
  • Relief Valve
     

    Valve that opens to protect steering or other hydraulic system when pressure becomes too high.

     
         
  • Reserve Capacity Rating
     

    The amount of time a battery will continue to provide an acceptable current flow when not being recharged by the alternator.

     
         
  • Reserve Distance
     

    Amount of travel remaining between pedal and floor when brakes are applied.

     
         
  • Reservoir
     

    A tank or other container to hold a supply of fluid (such as the brake master cylinder reservoir).

     
         
  • Resistance
     

    Opposition to current flow.

     
         
  • Resistance Plug Wire
     

    Special type of spark plug wire that eliminates most radio interference.

     
         
  • Retracting and Hold-Down Springs
     

    Springs that pull the shoes away from the brake drum surface when the pedal is released.

     
         
  • Retreads
     

    Tire bodies that have had new tread rubber applied to extend useful life.

     
         
  • Reverse Bias
     

    Arrangement in which diode acts as an insulator.

     
         
  • Reverse Flushing
     

    System cleaning done by forcing water backward through the radiator and block to remove scale and sediments.

     
         
  • Reverse Idler Shaft
     

    Shaft in a manual transmission on which the reverse idler gear is mounted.

     
         
  • Reverse Polarity
     

    Accidental backward connection of primary wires.

     
         
  • Rich Fuel/Air Ratio
     

    A fuel/air mixture that contains more fuel than needed..

     
         
  • Ridge Reamer
     

    Device used to remove metal ridge formed at top end of cylinder due to metal wear.

     
         
  • Ring and Pinion Backlash
     

    The amount of space between the meshing gear teeth.

     
         
  • Ring and Pinion Noise
     

    Whining or howling sounds that change pitch with speed changed, usually caused by wear or damage to differential components.

     
         
  • Ring Expander
     

    Tool used to spread a ring sufficiently to slip it over the piston.

     
         
  • Ring Gap
     

    Space between the ends of a piston ring.

     
         
  • Ring Gap Spacing
     

    Staggered alignment of ring gaps to reduce ring wear.

     
         
  • Ring Gear
     

    Large gear in differential that is driven by the pinion gear and, in turn, drives the spider gears.

     
         
  • Ring Gear Runout
     

    Amount of wobble that occurs as the gear rotates.

     
         
  • Ring Groove Cleaner
     

    Special scraper used to loosen and remove deposits from piston grooves.

     
         
  • Ring Markings
     

    Information cast into the ring to show the top side or proper positioning on piston.

     
         
  • Ring Spacers
     

    Thin steel rings inserted next to compression rings to restore proper side clearance.

     
         
  • Ring-to-Groove Clearance
     

    Also called ring side clearance, this is the space between a compression ring and the edges of the groove in the piston.

     
         
  • Rocker Arm
     

    Pivoted mechanism that operates valves.

     
         
  • Rod Bearing Knock
     

    Rapping sound resulting from excessive wear of bearings.

     
         
  • Rod Bolt Covers
     

    Temporary protective coverings, such as pieces of rubber hose, used when inserting piston and connecting rods in cylinders.

     
         
  • Rod Bolt Torque
     

    Recommended degree of tightness for connecting rod bolts.

     
         
  • Rod Cap Numbers
     

    Numbers used to match sets of rods and rod caps.

     
         
  • Rod Journals
     

    Machined and polished surfaces on the crankshaft to which the connecting rods are attached.

     
         
  • Rollover Valve
     

    Safety feature that prevents gasoline from leaking out tank vent if car rolls over.

     
         
  • Roller Lifter
     

    One with a roller riding on the cam lobe to reduce wear.

     
         
  • Rolling Resistance
     

    A measure of the amount of resistance that is generated as a tire rolls on the road surface.

     
         
  • ROM
     

    Read-only memory.

     
         
  • Rosin Core Solder
     

    Soft metal compound used to join electrical wires. The rosin is a non-corrosive flux to aid bonding.

     
         
  • Rotary Brush
     

    A stiff brush, used with an air tool for cleaning parts.

     
         
  • Rotary Pump
     

    Oil pump using star-shaped rotors.

     
         
  • Rotor
     

    A rotating contact inside the distributor that routes electrical pulses from the coil to the spark plugs. Also, the metal disc against which brake pads are forced to stop vehicle.

     
         
  • Rotor Current Test
     

    Method used to check alternator windings for an internal short.

     
         
  • Rotor Winding Open
     

    An open (broken) winding in an alternator rotor.

     
         
  • Rotor Winding Short
     

    short-to-ground fault in an alternator rotor.

     
         
  • RTV
     

    Room Temperature Vulcanizing - a type of sealant that cures at approximately 72F.

     
         
  • Rust Penetrant
     

    Lubricant that helps loosen rusted joints or fasteners.

     
         
  • Rzeppa CV-Joint
     

    Ball-and-cage type constant velocity joint used on front-wheel drive vehicles

     
         
  • Salvage Auction
     

    A place where salvage vehicles are auctioned off to highest bidder. Many salvage auctions are now available over the internet.

     
         
  • Salvage Yard
     

    See Automotive Recycling Facility.

     
         
  • Scrapped/Destroyed
     

    The Vehicle has been reclaimed for its metal content.

     
         
  • Seal
     

    A device that prevents passage of fluid beyond some point.

     
         
  • Sheet Metal
     

    The exterior metal parts. Examples fenders, hoods, doors etc.

     
         
  • Shop Estimate
     

    The preliminary assessment of damages and costs of repairs that will be used as a guideline for making repairs to the vehicle.

     
         
  • Sidewall
     

    The side part of the tire that connects the tread to the wheel.

     
         
  • Slip
     

    A condition where the clutch or automatic transmission seems to disengage and allows engine to rev up without transferring power to the wheels.

     
         
  • Solenoid
     

    Large capacity relay designed to energize the starter when you turn the key.

     
         
  • Sparkplug
     

    The electrical device that converts the high voltage surge into a spark to ignite the air-fuel mixture in the cylinder.

     
         
  • Speedometer
     

    Device on the instrument panel to display current vehicle speed.

     
         
  • Spring
     

    A device used to hold the vehicle up while providing a cushion against bumps or dips in the road. They can be coil, leaf or torsion bar.

     
         
  • Stall
     

    A condition where the engine shuts off, usually when coming to a stop.

     
         
  • Starter
     

    Electrical motor that cranks the engine, enabling it to start.

     
         
  • Steering Box
     

    A mechanism at the lower end of the steering column which converts rotary motion to transverse linear motion.

     
         
  • Steering
     

    Illegal practice whereby a representative of the party paying the bill tries to influence a vehicle owner to take their vehicle to a particular person or body shop for repairs.

     
         
  • Steering Pump
     

    A pump that provides hydraulic pressure for power steering, which makes it easier to turn the steering.

     
         
  • Sublet
     

    To contract services to be performed by an outside company, i.e. alignments, glass replacement, theft recovery.

     
         
  • Sump
     

    The pan at the bottom of the automatic transmission that collects fluid and holds it there for the transmission to use.

     
         
  • Surge
     

    Unevenness in the power output of an engine due to a fault in the air, fuel or ignition systems.

     
         
  • Safety Rim
     

    Wheel designed with small ridges that hold a tire in place if a blowout or flat occurs.

     
         
  • Safety Washer
     

    On a non-driving wheel, flat washer that keeps wheel bearing from rubbing on spindle adjusting nut.

     
         
  • Satellite Face
     

    Valve face coated with hard metal to withstand high temperatures.

     
         
  • Saving Memory
     

    A method of preventing loss of information in computer memory by connecting a small voltage source to it before disconnecting the vehicle's battery cables.

     
         
  • Scanner
     

    Electronic system used to analyze engine and computer operations.

     
         
  • Schrader Valve
     

    A spring-loaded valve, similar to a tire valve, used in air conditioning systems.

     
         
  • Screw Extractor
     

    Tool threaded opposite normal direction, so it can be used to unscrew a broken bolt or screw.

     
         
  • Seal
     

    A formed material or paste-like substance used to prevent leaks.

     
         
  • Seal Alignment Tool
     

    Device used to center seal around the crankshaft snout when mounting some engine front covers.

     
         
  • Sealant
     

    A material applied, in liquid or paste form, to prevent leakage between parts.

     
         
  • Sealing Rings
     

    Rings placed around either end of a turbo shaft to keep oil from leaking into the turbocharger housing.

     
         
  • Seal Part Number
     

    Code number stamped on a seal that is used when ordering a replacement.

     
         
  • Seat Width
     

    The area of the valve seat that is actually in contact with the valve face.

     
         
  • Secondary
     

    In a carburetor, the components that operate under high engine output conditions.

     
         
  • Secondary Circuit
     

    In an ignition system, all components operating on coil (high) voltage.

     
         
  • Secondary Pattern
     

    Pattern of high-voltage (ignition secondary) changes, as shown on an oscilloscope.

     
         
  • Secondary Wire
     

    Wire used in a vehicle ignition system. It carries high voltage from coil to spark plugs.

     
         
  • Secondary Wire Resistance
     

    A type of test performed to check condition of a spark plug wire or coil wire.

     
         
  • Sector Shaft
     

    Output gear in a re-circulating ball gearbox.

     
         
  • Select Fit Parts
     

    Parts that have been selected and installed to improve fit or clearance.

     
         
  • Self-Diagnosis
     

    The ability of a computer system to check circuits and output a code showing the nature or location of the problem.

     
         
  • Self-Sealing Tire
     

    One with a scaling compound applied to its liner to stop air leakage in case of puncture.

     
         
  • Semi-Centrifugal Clutch
     

    One that uses weighted release levers or rollers on the pressure plate, and the effects of centrifugal force, to increase clamping pressure on the clutch disk.

     
         
  • Semiconductor
     

    Substance that acts as an insulator or a conductor, depending upon conditions.

     
         
  • Semi-Floating Axle
     

    Most common type of rear axle for automobiles.

     
         
  • Sensor
     

    Device that monitors and reports a condition (such as engine temperature) to the vehicle computer.

     
         
  • Sensor Rotor
     

    A toothed wheel that operates at the same rpm as the vehicle wheel.

     
         
  • Separator
     

    An insulating material placed between plates of a battery.

     
         
  • Service Manager
     

    Person responsible for the complete service and repair operation.

     
         
  • Service Manual
     

    Book with detailed information on specific car repairs. Also called a shop manual.

     
         
  • Service Publications
     

    In addition to service manuals, there are other publications (such as owner's manuals and technical bulletins) that provide information on vehicle servicing.

     
         
  • Service Valves
     

    Points at which pressures in an air conditioning system can be checked, and refrigerant removed or replaced.

     
         
  • Servo
     

    Piston that operates a band in an automatic transmission.

     
         
  • Servo Action
     

    Situation in which primary shoe of a drum brake system helps apply the secondary shoe.

     
         
  • Servo Motor
     

    One that can be stopped in exact positions (degrees of rotation).

     
         
  • Servo Motor Actuator
     

    A small DC motor that can turn or move parts.

     
         
  • Set Screw
     

    Headless fastener used to secure a part on-to a shank.

     
         
  • Shaft Run-Out
     

    Wear or damage (bending) causing a shank to not run true around its axis.

     
         
  • Sharp Valve Margin
     

    A result of excessive grinding of valve face, leaving no margin.

     
         
  • Shell
     

    A component of an automatic transmission clutch that connects the front clutch drum and the sun gear of a planetary gear set.

     
         
  • Shift Fork
     

    Device that physically moves synchronizer and gear together as a result of shift lever (gearshift) movement.

     
         
  • Shift Lever
     

    The handle operated by the vehicle driver to manually shift from gear to gear.

     
         
  • Shift Linkage Adjustment
     

    Making sure transmission linkage positions match the gear selector positions.

     
         
  • Shift Linkage Alignment Pin
     

    Tool used to properly align shift linkage rods for proper operation.

     
         
  • Shift Rail
     

    A manual transmission linkage that is contained within the transmission case.

     
         
  • Shock Absorber
     

    Device that uses air or hydraulic pressure to dampen up-and-down motion of vehicle.

     
         
  • Shock Actuators
     

    Solenoid-operated valves that control fluid flow inside shock absorbers in an electronic shock absorber system.

     
         
  • Shock Bounce Test
     

    Method of quickly checking whether shock absorbers need replacement.

     
         
  • Shock Compression and Extension
     

    Actions of shock absorbers resulting from the vehicle traveling over road bumps.

     
         
  • Shock Mode Switch
     

    Dash switch that allows driver to select desired ride stiffness in an electronic shock absorber system.

     
         
  • Shop Supervisor
     

    A person in charge of a group of technicians in a large garage.

     
         
  • Short Block
     

    The bottom end of the engine, including the cylinders, pistons, and crankshaft.

     
         
  • Short Circuit
     

    Excess current flow that occurs when a conductor touches ground.

     
         
  • Shorted Condenser
     

    One with a direct electrical connection to ground.

     
         
  • Shorted Injector Coil
     

    A short-circuited solenoid coil is preventing injector operation.

     
         
  • Shroud
     

    Enclosure around a fan, used to direct airflow through the radiator.

     
         
  • Sidewall
     

    Portion of tire between tread and bead.

     
         
  • Simple Circuit
     

    One consisting of a power source, a load, and conductors.

     
         
  • Single-Point
     

    Injection system with fuel sprayed from a single location into the intake manifold.

     
         
  • Sintered Bronze Filter
     

    A porous metal fuel filter.

     
         
  • Six-Point
     

    Box end wrench with six indentations, or gripping teeth.

     
         
  • Slant Engine
     

    One with a single bank of cylinders tilted to one side.

     
         
  • Slave Cylinder
     

    Hydraulic cylinder that produces the movement of the clutch fork.

     
         
  • Slide Hammer Puller
     

    Tool used to break loose and remove an axle that is stuck in its housing.

     
         
  • Slipper Skirt
     

    Material remaining after part of piston below pin is removed for better crankshaft clearance.

     
         
  • Slip Rings
     

    Components mounted on the rotor shaft of a generator to provide current to rotor windings.

     
         
  • Slip Yoke
     

    Component that connects transmission to the front universal joint of the driveline.

     
         
  • Slow Charger
     

    One that feeds a small current into the battery over a long period of time.

     
         
  • Smog
     

    The cloud of airborne pollutants visible over major population centers.

     
         
  • Smoke Meter
     

    Device for testing the amount of smoke (ash or soot) in diesel exhaust.

     
         
  • Smooth DC
     

    Direct current without "ripples" or "spikes" due to fluctuating voltages.

     
         
  • Snap Ring
     

    Spring steel ring that snaps into a groove to act as a retainer on a shaft.

     
         
  • Sodium Filled Valve
     

    Hollow construction accepts sodium filling for more even cooling.

     
         
  • Soft Failure
     

    One that is intermittent, such as the make/break connection from a loose terminal.

     
         
  • SOHC
     

    Single overhead cam engine.

     
         
  • Soldering Gun
     

    Tool that applies heat to joined wires so that solder can be melted into the joint.

     
         
  • Solenoid Actuator
     

    One with a moving metal core that is actuated by an induced magnetic field.

     
         
  • Solvent Tank
     

    Container holding a cleaning solution used for removing grease and other dirt from a part.

     
         
  • Sonar Sensor
     

    Sound wave sensor used to detect road conditions in some electronic shock absorber systems.

     
         
  • Spark Ignition
     

    System that uses an electric arc to ignite fuel.

     
         
  • Spark Knock
     

    Noise caused by spark plug firing too early.

     
         
  • Spark Line
     

    Oscilloscope line showing voltage needed to maintain an arc across the spark plug gap.

     
         
  • Spark Plug
     

    Devices that emit an electrical arc at the tip to ignite the air-fuel mixture in an engine cylinder.

     
         
  • Spark Plug Gap
     

    See Plug gap.

     
         
  • Spark Test
     

    Check of the spark intensity (brightness and length of arc).

     
         
  • Spark Tester
     

    Device used to cheek operation of ignition system.

     
         
  • Specialized Manual
     

    Service manual devoted to a specific vehicle area, such as engines or braking systems.

     
         
  • Specialized Mechanic
     

    A technician who is an expert on one system of a car.

     
         
  • Special Tools
     

    Fixtures or tools needed for certain repairs or adjustments. They are described in service manuals.

     
         
  • Specific Gravity
     

    Weight or density of a liquid.

     
         
  • Speed Control System
     

    Method of regulating a car's throttle to maintain a preset speed. Also called cruise control.

     
         
  • Spider Gears
     

    Idler and axle gears in the differential that drive the rear axles of a vehicle.

     
         
  • Spindle
     

    Stationary shaft used to support rotating wheel assembly on non-driving wheels.

     
         
  • Spindle Adjusting Nut
     

    A nut threaded on end of wheel spindle to adjust wheel bearing.

     
         
  • Spin On Oil Filter
     

    One that is replaced as a unit.

     
         
  • Splash Oiling
     

    Oil distributed to needed areas by spraying or splashing.

     
         
  • Splines
     

    A series of slots cut into a shaft and mating part.

     
         
  • Spongy Brakes
     

    Braking system that is "soft" feeling, usually as a result of air trapped in the hydraulic system.

     
         
  • Spring Bind
     

    Situation that can occur when a valve spring is fully compressed and locks the valve train.

     
         
  • Spring Fatigue
     

    Weakening of springs that allows the height of the car (and thus road clearance) to decrease.

     
         
  • Spring Free Length
     

    The length of a spring when removed from the engine.

     
         
  • Spring Rate
     

    The stiffness or tension; amount of weight needed to compress or bend a spring.

     
         
  • Sprocket Timing Marks
     

    Lines, circles, or dots on crankshaft and camshaft sprockets, aligned to set engine timing.

     
         
  • Spur Gears
     

    Those with teeth cut parallel to the centerline of the drive shaft.

     
         
  • Squish Area
     

    Part of a wedge-shaped combustion chamber.

     
         
  • Staking
     

    Making a small dent in cylinder head metal next to a valve seat to hold it in place after replacement.

     
         
  • Stall
     

    Work area of a repair shop.

     
         
  • Stalling
     

    Condition in which the engine merely stops running.

     
         
  • Stall Speed
     

    Highest speed of impeller rotation in a torque converter without rotation of the turbine.

     
         
  • Stall Test
     

    Method used to shop-test for transmission slippage.

     
         
  • Starter Current Draw Test
     

    Starting test that establishes the number of amps used by the starting system.

     
         
  • Starter Ground Circuit Resistance Test
     

    Check of all parts between the battery negative and the starting motor ground for excess resistance.

     
         
  • Starter Mounted Solenoid
     

    One with a plunger that moves to engage the pinion gear with the flywheel gear.

     
         
  • Starter Relay
     

    Device that uses a small current flow from the ignition switch to control a larger current flow to the starter solenoid.

     
         
  • Starter Shims
     

    Thin metal pieces used to adjust the space between the pinion gear and the flywheel gear.

     
         
  • Starter Solenoid
     

    A high current relay that energizes the starter motor.

     
         
  • Starting Headlight Test
     

    Starting test conducted with headlights turned on to provide a load on the battery.

     
         
  • Starting Motor Rebuild
     

    Process involving disassembly, cleaning, parts replacement, and reassembly of the motor.

     
         
  • Starting System
     

    Electric motor and other components used to rotate the engine until it starts.

     
         
  • Star Wheel
     

    Adjusting screw assembly for drum brakes.

     
         
  • States of Matter
     

    Forms in which a substance can exist (solid, liquid, gas).

     
         
  • Static Imbalance
     

    Lack of balance that causes a wheel to vibrate up and down as it rolls.

     
         
  • Static Pressure Reading
     

    A reading made with the engine off to determine whether a system has an adequate refrigerant charge.

     
         
  • Stator
     

    The stationary magnetic field in a generator. Also component of torque converter that improves oil circulation and thus, torque.

     
         
  • Stator Support
     

    A stationary tube surrounding the input shaft of a torque converter and supporting the stator.

     
         
  • Stator Test
     

    Ohmmeter check for open or shorted windings in the stator.

     
         
  • Steering Axis Inclination
     

    Angle formed by the inward tilt of ball joints, king pin, or struts.

     
         
  • Steering Column
     

    Assembly consisting of the steering wheel, steering shaft, ignition key mechanism and associated parts.

     
         
  • Steering Gearbox
     

    Gear assembly that turns rotary motion into linear (straight line) left-right motion.

     
         
  • Steering Knuckle
     

    Component that provides support for wheel spindle or bearings surrounding an axle.

     
         
  • Steering Linkage
     

    Components connecting steering gearbox to steering knuckles.

     
         
  • Steering Sensor
     

    Provides wheel orientation and speed data to computer in electronic shock absorber system.

     
         
  • Steering Shaft
     

    Component that transfers turning motion from steering wheel to steering gearbox.

     
         
  • Steering System
     

    The components that let the driver change direction of a vehicle.

     
         
  • Steering Wheel Play
     

    Excessive movement of wheel without causing front wheel movement.

     
         
  • Stem Type Valve
     

    Manual valve that is opened or closed by screwing the valve stem in or out.

     
         
  • Stethoscope
     

    A medical device, also used by auto technicians to better hear internal engine noises.

     
         
  • Stiff Clutch Pedal
     

    A condition caused by binding or other restriction in the clutch mechanism, making the pedal hard to depress.

     
         
  • Stoichiometric Fuel Mixture
     

    A perfect (chemically correct) air-fuel mixture.

     
         
  • Straightedge
     

    A metal ruler or bar, with one edge known to be smooth and straight, used to determine flatness of surfaces.

     
         
  • Strap
     

    Connector between cells of a battery.

     
         
  • Stratified Charge
     

    A combustion chamber design that first ignites the air-fuel mixture in a small chamber connected to the main chamber.

     
         
  • Strut Assembly
     

    Suspension component combining shock absorber, coil spring, and upper damper unit. It replaces the upper control arm.

     
         
  • Strut Cartridge
     

    Replaceable shock absorber unit on a MacPherson strut.

     
         
  • Strut Rod
     

    A rod that fastens to the control arm and frame to keep arm properly oriented.

     
         
  • Stuck Valve
     

    One that will not move up and down freely in the guide; usually, a condition occurring after long storage.

     
         
  • Stumble
     

    See Hesitation.

     
         
  • STY
     

    Suction throttling valve.

     
         
  • Supercharger
     

    Air pump used to push denser fuel-air charge into combustion chambers for increased power.

     
         
  • Superheat Switch
     

    One that shuts down an air conditioning system if refrigerant or oil levels are low.

     
         
  • Superimposed Pattern
     

    Oscilloscope pattern in which the traces for all cylinders are placed one on top of the other.

     
         
  • Surging
     

    Condition in which engine power fluctuates up and down.

     
         
  • Suspension Leveling System
     

    Suspension system designed to keep vehicle level and at proper height even when carrying a heavy load in the truck.

     
         
  • Suspension System
     

    Components that let the wheels move up and down without body movement.

     
         
  • Suspension System Computer
     

    One that accepts sensor input and regulates the stiffness of the vehicle's suspension system.

     
         
  • Sway Bar
     

    A stabilizer that keeps the vehicle body from leaning excessively in turns.

     
         
  • Swing Axle
     

    Axle provided with U-joints to allow for up-and-down suspension movement. Used on vehicles with differential mounted solidly on frame.

     
         
  • Swirl Chamber
     

    Combustion chamber shape that causes the air-fuel mixture to spin as it enters, for better mixing.

     
         
  • Switching Sensor
     

    One that opens or closes a switch in response to a change in condition.

     
         
  • Switch Self Test
     

    Systematic actuation of various switches while using the scanner, providing a check of switch operation.

     
         
  • Synchronizer
     

    Assembly of hub, sleeve, and other components that locks the selected output gear to the output shaft to transmit power. It permits meshing of gears without grinding.

     
         
  • Synthetic Fuels
     

    Liquid fuels made from such solids as coal or tar sand.

     
         
  • System
     

    A group of related parts that perform a specific function.

     
         
  • Systematic Approach
     

    Combining knowledge and a logical process of elimination to solve a problem.

     
         
  • System Bleeding
     

    Removing any trapped air from the entire braking system.

     
         
  • Terminal Ends
     

    Metal clamps or flanges that connect battery cables to the battery.

     
         
  • Thermostat
     

    A valve that keeps coolant from flowing until it reaches about 93 centigrade.

     
         
  • Tie rod-end
     

    A small ball-and-socket joint used as part of the steering linkage.

     
         
  • Timing Belt
     

    A belt that runs between the crankshaft to turn the cam- shaft and keep the two in the correct relative positions.

     
         
  • Torque
     

    A measurement of force. The drive train convert’s the engine’s power to torque at the wheels.

     
         
  • Totaled Vehicle
     

    A determination made by an insurance company when the cost of repair plus the salvage value is greater than the car’s Blue Book value

     
         
  • Transmission
     

    All the mechanisms that carry the power from the engine to the wheels, the clutch and gearbox, as well as the differential and axles.

     
         
  • Transmission Oil
     

    A lubricant specially compounded for vehicle transmissions.

     
         
  • Tread
     

    That part of the tire that comes into contact with the road.

     
         
  • Tune-up
     

    To inspect, test, adjust, or replaces part of an engine to restore it to its best possible performance.

     
         
  • Turn Into The Skid
     

    The technique for counteracting a rear wheel skid. Turn the top of the steering wheel in the same direction as the skid, with the brake and accelerator released.

     
         
  • Tire Rotation
     

    To rotate the tires to a different corner of the car, allowing them to more evenly. Thought by some to be actually transfer irregular wear from tire to tire hence actually increase type wear.

     
         
  • Tach-Dwell:
     

    Combined meter that measures engine rpm and degrees of breaker cam rotation for distributor point adjustment.

     
         
  • Tailpipe
     

    Tubing that carries exhaust from muffler to point at rear or side of the vehicle, where it can be dispersed.

     
         
  • Tank Pickup-Sending Unit
     

    Component that extends into fuel tank to withdraw fuel and send fuel-level information to the fuel gauge.

     
         
  • Tap
     

    Tool for cutting threads inside a hole.

     
         
  • Tappet Clearance
     

    The proper degree of tension (neither too tight nor too loose) for the valve train of an engine.

     
         
  • Taxable hp
     

    General rating of engine size.

     
         
  • TBI
     

    Throttle body (single-point) fuel injection.

     
         
  • TBI Rebuild
     

    Similar to a carburetor rebuild.

     
         
  • TDC
     

    Top Dead Center. When the engine cylinder piston achieves its highest position within the cylinder.

     
         
  • Telescoping Gauge
     

    Spring-loaded device for measuring inside dimensions (such as a cylinder bore).

     
         
  • Temperature Gauge Tester
     

    Electronic device for testing accuracy of engine temperature gauge.

     
         
  • Tensile Strength
     

    The amount of stretching a material can withstand before breaking.

     
         
  • Terminals
     

    The positive and negative posts or threaded connectors on a battery.

     
         
  • Test Light
     

    Device that will light up to show the presence of voltage (electrical potential).

     
         
  • Test Light Code
     

    Trouble code read by counting the flashes of a test light.

     
         
  • Thermal Efficiency
     

    A comparison of fuel burned to horsepower output.

     
         
  • Thermo-Time Switch
     

    Control circuit that energizes cold start injector when temperature is low enough.

     
         
  • Thermostatic Air Cleaner
     

    System that heats the air being drawn through the engine air inlet to prevent carburetor icing.

     
         
  • Thermostatic Fan Clutch
     

    Clutch that locks up for maximum airflow when it reaches operating temperature.

     
         
  • Thermostatic Spring
     

    Bimetal coil spring that responds to engine heat and opens or closes the choke.

     
         
  • Thermostatic Switch
     

    Electrical component that shuts off an air conditioning Compressor when the evaporator temperature approaches the freezing point.

     
         
  • Thermostat Rating
     

    Temperature at which the thermostat opens.

     
         
  • Thread Pitch
     

    Number of threads per inch or (metric sizes) distance between threads.

     
         
  • Throttle Body
     

    Section of the carburetor containing the throttle valves.

     
         
  • Throttle Positioner
     

    Device that works with idle air control valve in a TBI system to control idle speed.
    Throttle Position Sensor Device that senses how much throttle is opening or closing.

     
         
  • Throttle Return Dashpot
     

    Diaphragm device that prevents engine stalling when returning from high speed to idle operation.

     
         
  • Throttle Valve
     

    Disc-shaped valve that controls airflow through the air horn.

     
         
  • Throw-Out Bearing
     

    Bearing that decreases friction between clutch fork and pressure plate.

     
         
  • Thrust Bearing
     

    Special bearings with flanges that limit crankshaft forward and rearward movement.

     
         
  • Thrust Washers
     

    Metal pieces that can be slipped between block and crankshaft to limit endplay.

     
         
  • Tie Rod
     

    Connectors between rack ends and steering knuckles.

     
         
  • Tightening Sequence
     

    Recommended pattern for tightening multiple fasteners to obtain even tension.

     
         
  • Timed Injection
     

    System timed to inject fuel as the intake valves open.

     
         
  • Timing Advance
     

    Making the spark plug fire sooner in the compression stroke.

     
         
  • Timing Belt
     

    Rubber belt performing the same job as timing chain or timing gears.

     
         
  • Timing Belt Cover
     

    See Engine front cover.

     
         
  • Timing Belt Sprockets
     

    Toothed wheels driving a cogged timing belt.

     
         
  • Timing Belt Tension
     

    The proper degree of tightness; one that will transmit power efficiently without causing excessive belt wear.

     
         
  • Timing Belt Tensioner
     

    Part performing same function as timing chain tensioner.

     
         
  • Timing Chain
     

    Sprocket-and-chain combination that performs same function as timing gears.

     
         
  • Timing Chain Guide
     

    Channel that helps support chain and prevents chain slap.

     
         
  • Timing Chain Tensioner
     

    Spring-loaded plastic or fiber block that pushes on chain to eliminate slack.

     
         
  • Timing Gear Backlash
     

    The amount of clearance between timing gear teeth.

     
         
  • Timing Gear Marks
     

    Markings on differential ring and pinion gear sets that permit proper alignment.

     
         
  • Timing Gear Runout
     

    The amount of wobble that occurs when gear is rotating.

     
         
  • Timing Gears
     

    Meshing gears on crankshaft and camshaft that rotate camshaft at half crankshaft speed.

     
         
  • Timing Light
     

    Strobe-like light that makes moving parts appear to stand still, allowing timing marks to be observed.

     
         
  • Timing Marks
     

    Calibrating marks on timing gears or other timing devices.

     
         
  • Timing Retard
     

    Making the spark plug fire later in the compression stroke.

     
         
  • Timing Sprockets
     

    Gear-like toothed wheels used with timing chain.

     
         
  • Tire Bead
     

    Wire ring, encased in rubber, that helps hold tire sidewall against the rim.

     
         
  • Tire Changer
     

    Air-powered machine that automates many steps of tire changing.

     
         
  • Tire Gauge
     

    Small instrument used to check inflation pressure of a tire.

     
         
  • Tire Impact Damage
     

    Punctures, cuts, or tears caused by running over debris in road.

     
         
  • Tire Markings
     

    Information shown on the sidewall to indicate inflation pressure, load carrying ability, size, and other data.

     
         
  • Tire Plug
     

    Rubber insert sometimes used to repair punctures. The tire industry discourages the use of plugs under most circumstances.

     
         
  • Tire Ply
     

    Layer of fabric or other material that forms the carcass or body of the tire.

     
         
  • Tire Rotation
     

    Moving tires to different wheels periodically to even out wear.

     
         
  • Tire Wear Pattern
     

    Areas of tread that are worn off, which can provide information on causes of the wear.

     
         
  • Toe
     

    Degree to which opposing wheels are on converging or diverging lines (not parallel). Also, the narrow part of a gear tooth.

     
         
  • Toe-out On Turns
     

    Steering feature that turns inside wheel more sharply than outside wheel.

     
         
  • Torque Converter
     

    Fluid coupling that acts as a clutch on an automatic transmission.

     
         
  • Torque Multiplication
     

    Variation in torque achieved by turning the impeller of a torque converter faster than the turbine.

     
         
  • Torque Specifications
     

    Information on the correct amount of force to be applied in tightening a fastener.

     
         
  • Torque Tube
     

    A solid steel drive shaft enclosed in a hollow tube, with a single swivel joint at the front.

     
         
  • Torque Wrench
     

    A tool that is used to indicate the amount of force being applied to a fastener.

     
         
  • Torsion Bar
     

    Spring steel rod that operates by twisting and untwisting.

     
         
  • Torsion Springs
     

    Small coil springs that help absorb the shock and vibration that occur when the clutch engages.

     
         
  • Tracking
     

    The position or direction of the front wheels in relation to the rear wheels.

     
         
  • Track Rod
     

    Metal rod used to prevent axle side-to-side movement when cornering.

     
         
  • Tram Gauge
     

    Instrument used to compare distances between the front and rear of a set of tires for toe adjustment.

     
         
  • Transaxle
     

    A combination of transmission and differential in one case, used on front-wheel-drive vehicles.

     
         
  • Transaxle Differential
     

    Transaxle assembly that transfers torque to driving axles and allows them to rotate at different speeds.

     
         
  • Transaxle Dipstick
     

    Metal rod used to check level of lubricant in transaxle.

     
         
  • Transaxle External Adjustments
     

    Clutch, shift linkage, bands, and other components often can be adjusted from outside the transaxle housing.

     
         
  • Transaxle Fill and Drain Plugs
     

    Removable plugs that can be used to drain and refill lubricant in a transaxle.

     
         
  • Transaxle Filter
     

    Replaceable element used to trap metal particles and other debris circulating with the lubricant.

     
         
  • Transaxle Gearbox
     

    The transmission section of the transaxle, housing the forward and reverse gears.

     
         
  • Transaxle Input Shaft
     

    Main shaft that turns the gears in a transaxle.

     
         
  • Transaxle Output Shaft
     

    Shaft that transfers power to the ring and pinion gears of the differential.

     
         
  • Transaxle Pan
     

    Lubricant sump at bottom of a transaxle.

     
         
  • Transducer
     

    A device that changes an action or signal from one medium to another (an electrical pulse into a physical movement, for example).

     
         
  • Transfer Case
     

    A power takeoff unit that sends power to both the front and rear axle assemblies on a four-wheel-drive vehicle.

     
         
  • Transfer Case Fill Plug
     

    Removable plug to allow checking and adjusting of fluid level in the transfer case.

     
         
  • Transfer Pump
     

    A small pump that supplies fuel to a diesel injector.

     
         
  • Transistor
     

    Tiny electronic component that functions as a switch, but has no moving parts.

     
         
  • Transmission Case
     

    Metal housing surrounding and supporting the transmission.

     
         
  • Transmission Cooler
     

    A small separate radiator used to cool transmission oil in vehicles pulling heavy loads.

     
         
  • Transmission Diagnosis Chart
     

    A diagnostic aid listing symptoms and probable causes.

     
         
  • Transmission ID Tag
     

    A separate tag or set of' stamped numbers identifying the exact type of transmission being serviced.

     
         
  • Transmission Jack
     

    A special tool used to support the weight of a transmission as it is being removed from a vehicle.

     
         
  • Transmission Linkage
     

    System that connects the shift lever with the transmission shift forks.

     
         
  • Transmission Oil Cooler
     

    Small tank within the radiator, used to regulate transmission fluid temperature.

     
         
  • Transverse
     

    Crosswise; term used to identical an engine rotated 90 degrees from the traditional longitudinal mounting, typically found in front wheel drive cars.

     
         
  • Tread
     

    Outer surface of tire that contacts the road.

     
         
  • Trigger Wheel
     

    Rotating component with one tooth for each cylinder.

     
         
  • Tripod CV-Joint
     

    Constant velocity joint used on front wheel drive vehicles, consisting of a spider and ball arrangement inside a housing.

     
         
  • Trouble Code Chart
     

    Diagnostic aid that lists the trouble for each code.

     
         
  • Troubleshooting Chart
     

    A guide that lists methods for finding and correcting vehicle problems.

     
         
  • Tubeless
     

    Tire that does not have a separate inner tube to hold air.

     
         
  • Tumbler
     

    Ignition switch lock mechanism.

     
         
  • Tune-Up Parts
     

    Spark plugs, filters, and other periodic replacement items.

     
         
  • Turbine
     

    The driven fan assembly in a torque convener.

     
         
  • Turbine Housing
     

    The outer case that routes gases around the turbine wheel.

     
         
  • Turbine Wheel
     

    A fan-like wheel driven by the exhaust gases of an engine. It turns a shaft and compressor wheel.

     
         
  • Turbo Bearing
     

    Bearings supporting the turbo shaft.

     
         
  • Turbocharger
     

    A form of supercharger that is driven by exhaust gases.

     
         
  • Turbo Lag
     

    A short delay before turbo charging becomes effective.

     
         
  • Turbo Shaft
     

    Shaft connecting turbine and compressor wheels in a turbocharger.

     
         
  • Turning
     

    Term usually used for machining a brake drum or rotor, since process is carried out on a lathe.

     
         
  • Turning Radius Gauge
     

    Instruments that measure how many degrees left or right the front wheels are turned.

     
         
  • Turn Signal Flasher
     

    Bimetallic strip and heater unit that makes and breaks contact to cause on-off operation of the turn signals.

     
         
  • Twelve-Point
     

    Box end wrench with twelve indentations, or gripping teeth.

     
         
  • Twin I-Beam
     

    Double-axle suspension system used on some pickup truck models.

     
         
  • Two-Gas Analyzer
     

    Measuring instrument that provides reading~ of NC and CO levels in exhaust.

     
         
  • Two-Stroke Cycle Engine
     

    One that completes a full power-producing cycle with only one full crankshaft revolution.

     
         
  • Under gear
     

    All of the running gear on the underside of the vehicle. The suspension, steering, brakes and drivetrain.

     
         
  • Used Auto and Truck Parts
     

    See recycled OEM parts.

     
         
  • U-Joint Alignment Marks
     

    Scribed marks made on u-joint components before disassembly, allowing the joint components to be reassembled in the same positions to avoid possible imbalance and vibration.

     
         
  • Umbrella Valve Seal
     

    Rubber or plastic seats that fit over opening at top of valve guide to keep oil out of them.

     
         
  • Under Inflation
     

    Operating tire with a lower-than recommended air pressure.

     
         
  • Undersize Hearing
     

    One designed for use on a crankshaft journal that has been machined to a smaller diameter.

     
         
  • Uni-Body:
     

    A vehicle structure in which body and frame are one unit.

     
         
  • Universal Joint
     

    A flex joint allowing limited up-and down and side-to-side movement.

     
         
  • Unleaded Gasoline
     

    Fuel that does not contain lead-based antiknock additives.

     
         
  • Un-Sprung Weight
     

    The weight of vehicle parts that are not supported by springs, such as the wheels.

     
         
  • Up-Date PROM
     

    A PROXI with new programming that is plugged into the computer in place of the old one.

     
         
  • Valve
     

    1. A round place with a shaft attached. The plate opens and closes the intake or exhaust ports to the combustion chamber to control flow through the engine.

    2. A device that can be opened or closed to start or stop the flow of a liquid or gas.

     
         
  • Vibration
     

    A problem in the steering or suspension often caused by a wheel imbalance.

     
         
  • Voltage Regulator
     

    Electronic device that controls the charging voltage from the alternator to prevent it from overcharging.

     
         
  • Vacuum
     

    A pressure lower than atmospheric, in an enclosed area.

     
         
  • Vacuum Advance
     

    System that provides additional ignition advance when engine load is low at medium throttle positions.

     
         
  • Vacuum Booster
     

    Braking system booster actuated by vacuum.

     
         
  • Vacuum Choke Break
     

    A device that uses vacuum to open and close the choke to prevent engine flooding at startup.

     
         
  • Vacuum Delay Valve
     

    Mechanism that restricts airflow to slow down action of vacuum on a device.

     
         
  • Vacuum Gauge
     

    Test instrument used to read negative pressure values.

     
         
  • Vacuum Leak
     

    Loss of negative pressure due to crack or hole in a vacuum hose.

     
         
  • Vacuum Pump
     

    A device that provides vacuum for operation of the engine accessories.

     
         
  • Vacuum Switch
     

    One that opens or closes on a change in vacuum.

     
         
  • Vacuum Valve
     

    Valve inside radiator cap that allows flow of coolant from recovery tank back into radiator.

     
         
  • Valve
     

    Component that opens or closes a port to permit flow into and out of the combustion chamber.

     
         
  • Valve Adjusting Shims
     

    Thin metal plates used to alter the cam-to-valve clearance.

     
         
  • Valve Adjustment
     

    Correcting any malfunction in the opening and closing of valves actuated by mechanical lifters.

     
         
  • Valve Body
     

    Housing containing most of the valves used in operation of an automatic transmission.

     
         
  • Valve Core
     

    Threaded air valve that screws into place in a valve stem.

     
         
  • Valve Cover
     

    A metal or plastic cover over the top of the cylinder head.

     
         
  • Valve Float
     

    A tendency for valves to remain partly open, especially at high speeds. It usually results from a weak or broken valve spring.

     
         
  • Valve Grind Gasket Set
     

    Set of gaskets needed for top end reassembly after valve grinding.

     
         
  • Valve Grinding
     

    Process of machining a smooth surface on valve faces and valve stem tips.

     
         
  • Valve Guide
     

    Holes machined into the engine block to support the valve stems as they slide up and down.

     
         
  • Valve Guide Cleaner
     

    Rotating tool use to remove deposits from valve guides.

     
         
  • Valve Guide Insert
     

    Replacing the worn guide with a new one.

     
         
  • Valve Guide Knurling
     

    Grooving process that raises metal to restore inside diameter of guide.

     
         
  • Valve Job
     

    Servicing of the cylinder head and valve train.

     
         
  • Valve Lifter
     

    Component that is moved by the camshaft lobe and in turn moves the push rod or the rocker arm.

     
         
  • Valve Overlap
     

    The short period when both valves in a cylinder are open.

     
         
  • Valve Reliefs
     

    Indentations in a piston crown to provide valve clearance.

     
         
  • Valve Rotator
     

    Device that turns the valve to prevent carbon buildup.

     
         
  • Valve Seal
     

    Seals that fit over valve stems to prevent oil leakage.

     
         
  • Valve Seat
     

    Machined surfaces on the intake and exhaust ports, against which the valve rests and seals.

     
         
  • Valve Seat Angle
     

    The angle formed by the finished face of the seat.

     
         
  • Valve Seat Insert
     

    One that is pressed into a recess cut into the head.

     
         
  • Valve Seat Reconditioning
     

    Grinding or cutting valve seats to obtain a smooth surface.

     
         
  • Valve Seat Run out
     

    Improper centering, so that the seat is not centered around the valve guide after grinding or cutting.

     
         
  • Valves in Receiver
     

    Expansion and POA valves enclosed within the receiver drier of an air conditioning system.

     
         
  • Valve Spring
     

    Assembly that closes the valve when rocker arm pressure is removed.

     
         
  • Valve Spring Compressor
     

    A Tool used to compress valve springs during disassembly.

     
         
  • Valve Spring Installed Height
     

    The distance from top to bottom of the spring as installed in the cylinder head.

     
         
  • Valve Spring Seat
     

    Cup-shaped washer that holds the bottom of the valve spring.

     
         
  • Valve Spring Shim
     

    Precisely machined washer used to increase valve spring tension.

     
         
  • Valve Spring Shims
     

    Thin metal pies used to adjust spring. tension after valve grinding.

     
         
  • Valve Spring Tester
     

    Device for measuring the tension or pressure exerted by the spring.

     
         
  • Valve Stem
     

    A rubber inflation tube with a threaded metal core that snaps into a hole on the rim of a wheel designed for use with tubeless tires.

     
         
  • Valve Stem Cap
     

    Cap placed over end of valve stem to prevent stem wear.

     
         
  • Valve Stem Seal
     

    A seal placed over the end of the valve stem to prevent engine oil from entering the combustion chamber

     
         
  • Valve Timing
     

    Intervals at which valves open and close, determined by camshaft configuration.

     
         
  • Valve Train
     

    The parts that operate the engine valves, camshaft, lifters, push rods, rocker arms, and springs.

     
         
  • Vaporization
     

    A rapid change of state from liquid to gas.

     
         
  • Vapor Lock
     

    Condition caused by bubbles in fuel due to overheating. Can cause stalling, hard starting, or failure to start.

     
         
  • Vapor Separator-Filter
     

    Fuel filter that collects bubbles of vaporized fuel and returns them to the tank.

     
         
  • Variable Resistance Sensor
     

    One with internal resistance that changes in response to changes in a condition (such as temperature).

     
         
  • Variable Venturi Carburetor
     

    One in which the venturi size adjusts to maintain a constant air speed in the carburetor.

     
         
  • Vehicle Identification Number (VIN)
     

    Individual number identifying a vehicle and displayed on a plate attached to the body.
    Vehicle Maintenance Term for all operations performed to keep a vehicle in good running condition.

     
         
  • Vehicle Sensor
     

    Device that changes a condition into an electrical signal that can be used as an input by a computer.

     
         
  • Venturi
     

    Restriction (narrowed area) in air horn.

     
         
  • Vibration Damper
     

    Heavy, rubber-mounted wheel on front of crankshaft to counter harmonic vibrations.

     
         
  • VIN
     

    See Vehicle identification number.

     
         
  • Viscosity
     

    A measure of the thickness, or ability to flow, of a lubricant.

     
         
  • Voice Alert System
     

    Computer-based system that provides audible messages, in an electronically generated voice, to warn of safety problems or vehicle malfunctions.

     
         
  • Voltage
     

    Electrical pressure that causes current flow.

     
         
  • Voltage Drop
     

    Reduction of the amount of current flowing in a circuit.

     
         
  • Voltage Drop Tests
     

    Starting system tests that identify parts showing high resistance.

     
         
  • Voltage Generating Sensor
     

    One that changes voltage in response to external change.

     
         
  • Voltage Regulator
     

    Device used to control alternator output.

     
         
  • VOM
     

    Volt-ohm-milliammeter for determining electrical values.

     
         
  • V-type Engine
     

    One with two banks of cylinders, arranged in a "V" configuration.

     
         
  • Wankel
     

    A rotary engine with few moving parts.

     
         
  • Warped Cylinder Head
     

    A head with a distorted (twisted or curved) surface as a result of overheating.

     
         
  • Waste Gate
     

    A valve that limits the amount of boost developed by the turbocharger by venting excess exhaust gases.

     
         
  • Water Corrosion
     

    Injector damage caused by the presence of water in diesel fuel.

     
         
  • Water Detector
     

    Warning device that tells the driver there is water in diesel fuel.

     
         
  • Water Pump
     

    A pump (usually of the centrifugal type) that circulates coolant through the engine and radiator of a vehicle.

     
         
  • Water Pump Rebuild
     

    Process of disassembly, cleaning, parts replacement, and reassembling a water pump.

     
         
  • Wear Bar
     

    Solid bars of rubber across the tread that appear when a tire has worn to the safe limit.

     
         
  • Wear Sleeve
     

    Bushing between the axle and seal on a front-wheel drive vehicle.

     
         
  • Wedge Chamber
     

    Combustion chamber with a triangular shape.

     
         
  • Wet Charged
     

    Battery that is filled with electrolyte and fully charged at the factory.

     
         
  • Wet Compression Test
     

    Test made by placing small amount of oil in a cylinder with a low reading, to determine whether worn rings are cause of low compression.

     
         
  • Wet Sleeve
     

    A thick cylinder liner exposed to coolant.

     
         
  • Wheel Alignment
     

    Adjusting wheels of a vehicle to roll in a straight line.

     
         
  • Wheel Balancing Machine
     

    Device used to identify locations where weights must be placed to balance a tire.

     
         
  • Wheel Bearing
     

    Ball or roller bearing assemblies that reduce friction as wheels or axles rotate.

     
         
  • Wheel Brake Assemblies
     

    Components that use hydraulic pressure to apply friction for stopping vehicle.

     
         
  • Wheel Cover
     

    Metal or plastic disk designed to fit over center section of wheel for better appearance.

     
         
  • Wheel Cylinder
     

    Hydraulic piston that actuates braking at each wheel.

     
         
  • Wheel Cylinder Rebuild
     

    Process that typically involves honing the cylinder and replacing all rubber parts (cups and boots).

     
         
  • Wheel Hop
     

    A bouncing or up-and-down movement.

     
         
  • Wheel Puller
     

    A device used to remove pressed-on parts, such as gears.

     
         
  • Wheel Shimmy
     

    A side-to-side movement caused by dynamic imbalance.

     
         
  • Wheel Speed Sensors
     

    Magnetic pickups to detect wheel speed (used on antilock braking systems).

     
         
  • Wheel Weight
     

    Small pieces of lead that are clipped to the wheel rim to balance the wheel and tire combination.

     
         
  • Wiggle Test
     

    Physically moving wires and connectors to locate broken wires or other causes of intermittent problems.

     
         
  • Winding
     

    Loop of wire on a motor armature that generates a magnetic field.

     
         
  • Wire Wheel
     

    Cleaning tool with wires arranged radially, rotated at moderately high speed to remove carbon deposits from parts.

     
         
  • Wiring Diagram
     

    Drawings that show relationships of components in an electrical circuit.

     
         
  • Wiring Harness
     

    A group of primary wires enclosed in a protective plastic covering.

     
         
  • Work
     

    The result of force causing movement; measured in foot-pounds, watts, or joules.

     
         
  • Worm Shaft
     

    Input gear in a re-circulating ball gearbox.

     
         
  • Worn Cam Bearings
     

    After prolonged engine use, this condition can cause reduced oil pressure.

     
         
  • Worn Idler Arm
     

    Condition that can cause steering wheel play.

     
         
  • Worn Piston Rings
     

    Many engine problems arc caused by failure of worn rings to properly seal against cylinder walls.

     
         
  • Worn Rocker Arms
     

    Primarily cause noise (valve clatter).

     
         
  • Worn Tie Rod End
     

    A cause of excessive play in the steering wheel.

     
         
  • Worn Timing Chain
     

    Permits slack between camshaft and crankshaft sprockets, so valves no longer keep proper timing with the pistons.

     
         
  • Worn Joint
     

    Excessive play between the cross and yoke.

     
         
  • Worn Valve Guide
     

    Enlarged guide that allows valve to move excessively, causing various engine problems.

     
         
  • WOT Switch
     

    Device that shuts off air conditioning compressor.

     
         
  • Water Jacket
     

    The space within the cylinder block through which engine coolant flows.

     
         
  • Wheel Balancing
     

    A process of finding heavy spots on a tire and adding weight to the opposite sides to overcomes those heavy spots.

     
         
  • Windshield
     

    The front safety glass on a car.

     
         
  • Quickstart
     

    An easily ignited ether based fuel, dispensed from an aerosol into the air intake to assist a cold engine in starting, especially for diesel engines.

     
         
  • Quick Charge Test
     

    A method of determining whether battery plates are sulfated (no longer able to hold a charge).

     
         
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  • Quickstart
     

    An easily ignited ether based fuel, dispensed from an aerosol into the air intake to assist a cold engine in starting, especially for diesel engines.

     
         
  • Quick Charge Test
     

    A method of determining whether battery plates are sulfated (no longer able to hold a charge).

     
         
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  • Quickstart
     

    An easily ignited ether based fuel, dispensed from an aerosol into the air intake to assist a cold engine in starting, especially for diesel engines.

     
         
  • Quick Charge Test
     

    A method of determining whether battery plates are sulfated (no longer able to hold a charge).

     
         
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