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MacPherson Strut
Suspension system that uses one control arm and one strut for each wheel assembly.
Magnafluxing
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
eep, 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.
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.
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.
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.
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.
Quick Charge Test
A method of determining whether battery plates are sulfated (no longer able to hold a charge).
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
Tig htening or loosening rack adjustment screws as necessary for optimum steering.
Radial Runout
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.
Refractometer
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.
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