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    GLOSSARY TERMS

    P

    P&G Check
    The measurement of an engine's specifications, such as displacement, to determine the legality of competition using instruments provided by the P&G Manufacturing Company which allow such checks without the disassembly of the engine.
    Pace car
    A vehicle used in closed-course racing, usually a convertible passenger car, to lead the field up to speed for a rolling start. Also used to lead the field when a caution flag is displayed.
    Pace Lap
    The last lap just before the start of a closed-course race, as the pace car leads the field up to speed.
    Pacer
    A driver that runs at a constant or steady speed in oval-track racing.
    Package
    A combination of optional equipment or accessories offered for a new car buyer usually discounted when compared to individual component pricing.
    Package Tray
    The shelf behind the rear seat in a sedan. Early trunk-mounted air conditioners used ducts through the package tray as the intake and outlets of the unit.
    Pad
    A brake lining and metal back riveted or molded together. Two pads provide stopping friction by rubbing against both sides of a rotor or inside a drum when the brakes are applied.
    Pad-Wear Indicator
    A mechanical or electrical warning device on disc brakes that indicates need for pad replacement.
    Paddock Area
    A designated area behind or near the pit where race cars are tuned and prepared for qualifying and racing.
    PAFT
    An abbreviation for Program for Alternative Fluorocarbon Toxicity Testing.
    PAG
    An abbreviation for poly alkaline glycol.
    Paint
    A material, generally containing binders, solvents, and pigments, that is applied as a liquid to a surface, and forms a solid film for decoration and/or protection.
    Paint Shop
    The area in a repair facility where the vehicle is refinished by refinishing technicians or painters.
    Paint, Body, and Equipment Association (PBEA)
    A trade association of manufacturers, wholesalers, and distributors of vehicle paint and body-shop equipment.
    Pal Nut
    A thin pressed-steel nut used to lock a regular nut in place.
    Pallet
    A special platform, usually wooden, used to support and transport, usually by fork lift, components in the shop, or for storage between manufacture and assembly.
    Pan
    A term often used for oil pan.
    Pan Rails
    The sides of an oil pan that bolt to the engine block.
    Pancake Engine
    An engine having opposed pistons, such as a flat four or a flat six.
    Panel Beater
    A body shop worker.
    Panel Cutter
    Special snips used to cut through body sheet metal, designed to leave a clean, straight edge that can be easily welded.
    Panel Nut
    A thin nut used to hold parts or fittings to a firewall or bulkhead.
    Panel Truck
    An enclosed light truck or van having no windows in the cargo area.
    Panhard Rod
    A rod that is attached to the vehicle frame at one end and to the axle at the other end to prevent the chassis from moving side to side relative to the axle; used on a beam axle or de Dion axle type rear suspension.
    Paper
    Sheets of fibrous absorbent materials made from organic fibers that will swallow up liquids and may well disintegrate under such action if the liquid is a solvent for the binder.
    Parade Lap
    A lap or laps in closed-course racing before the pace lap to give the drivers an opportunity to warm up their tires and engines and to give the fans a chance for a good look at the cars at a slow speed.
    Parallel Circuit
    An electric circuit having two or more paths that the current flows through at the same time. The current is divided with more of it flowing through the path of least resistance.
    Parallel Linkage
    A steering linkage having equal-length tie rods.
    Parallel-Joint Type
    A drive shaft installation whereby all companion flanges and/or yokes in the drive line are parallel with each other with the working angles of the joints of a given shaft being equal and opposite.
    Parallelogram Linkage
    A steering linkage system having a short idler arm mounted on the right side in such a manner that it is parallel to the pitman arm.
    Parasitic Drag
    Any interference of the aerodynamic efficiency of a vehicle body such as may be caused by outside mirrors, door handles, antenna, and windshield wiper arms and blades.
    Parasitic Load
    An electrical load that is present when the ignition switch is in the OFF position.
    Parent Metal
    The original metal in a body panel to which another metal panel has been added.
    Park Contacts
    Electrical contacts, inside a windshield-wiper motor assembly, to provide current to the motor after the control switch has been turned to the OFF or PARK position, allowing continued motor operation until reaching the park position.
    Parking Brake
    A mechanically applied brake system, usually to the rear wheels or drive shaft, to prevent a parked vehicle's movement.
    Parking-Brake Cable
    A cable or cables that transmit brake-actuating force in the parking-brake system.
    Parking-Brake Equalizer
    A device used to equalize the pull between the parking brake actuator and two rear wheels.
    Parking-Brake System
    A brake system, intended to hold a vehicle stationary, in which one or more brakes may be held in the applied position without continued application of force to the control.
    Part Number (PN)
    The alphanumeric designating of a part as listed in a catalog or parts list.
    Part Out
    To sell an assembly, such as an engine, piece by piece.
    Particle
    A very small piece of dirt, metal, or other debris which can be contained in oil, air, or fuel that can be removed with a filter.
    Particulate
    A solid matter, mainly soot from burned carbon, in an internal combustion engine's exhaust.
    A form of solid air pollution such as microscopic solid or liquid matter that floats in the air.
    Particulate Emissions
    Solid particles, such as carbon and lead, found in vehicle exhaust; soot. A problem, especially in diesels.
    Particulate Trap
    An emissions control device in the exhaust system of a diesel engine which is used to capture particulate before they can enter the atmosphere.
    Parting Edge
    The excess flash material that is found around the edge of a part that has been cast in a two-piece mold.
    Partition Coefficient
    The ratio of the solubility of a chemical in water as compared to its solubility in oil.
    Parts Changer
    One who, without proper diagnostic skills, randomly changes parts until the remedy to a problem is found.
    Parts Chaser
    A vehicle used for errands.
    A person who runs errands, especially for buying parts.
    Parts Counterman
    One very knowledgeable in part numbers, and/or determining requirements who generally works in a parts-supply wholesale or retail outlet.
    Parts Distribution
    A wholesale, discount, or retail establishment that sells parts to the trade or do-it-yourselfer.
    Parts Manager
    One responsible for ensuring that the in-house stock of parts is adequate so the customer's parts are readily available to the service technician when needed.
    Parts per Million (ppm)
    A unit used to measure the amount of contamination in a substance, such as moisture in refrigerant.
    A measurement of the emissions of a motor vehicle given as the number of parts of a particular chemical within one million parts of exhaust gas.
    Parts Requisition
    A form that is used to order parts.
    Parts Specialist
    One who sells automotive engine and vehicle parts.
    Parts Washer
    A machine that is used to clean parts.
    Pass
    To run down a drag strip.
    Passages
    A term often used for coolant passages or water jacket.
    Passenger Car
    A four-wheeled, motor-driven vehicle that carries ten passengers or less, intended for use on streets and highways.
    Passive
    Receiving or subjected to an action without responding or initiating a corresponding action.
    Accepting without resistance or objection.
    Passive restraint
    Occupant restraints, such as air bags or seat belts, that operate automatically with no action required on the part of the driver or occupant, as mandated by Federal regulations to be used in all vehicles sold in the United States after 1990.
    Passive seal
    A seal that has no extra springs or tension devices to help make the seal, such as the O-ring seals on valves.
    Patch
    The area of contact of a tire with the road surface when the tire is supporting the weight of the vehicle.
    A small, rubber-like piece of material for repairing a puncture in an inner tube.
    A term often used for a temporary repair.
    Patch area
    A term used for tire contact area.
    PAW
    An acronym for plasma arc welding.
    Pawl
    A ratchet tooth that is used to lock a device.
    Payload
    The weight of the cargo that may be carried by a truck, determined by subtracting the curb weight of the vehicle and 150 pounds (68 kg) for each passenger from the gross vehicle-weight rating.
    PBEA
    An abbreviation for Paint, Body, and Equipment Association.
    PC Seals
    Valve stem seals made by Perfect Circle that have Teflon inserts to wipe the stems clean.
    PCV
    An abbreviation for positive crankcase ventilation.
    PCV Hose
    A Neoprene- or synthetic-rubber hose that is connected to one or both ends of a PCV valve.
    PCV Valve
    A vacuum-controlled metering device that regulates the flow of crankcase fumes in the positive crankcase ventilation system by allowing more flow at high speed than at low speed, and acts as a system shutoff in case of engine backfire to prevent an explosion in the crankcase.
    PDI
    An abbreviation for predelivery inspection.
    Peak
    Maximum, as in peak horsepower, meaning maximum horsepower.
    Peak Out
    The engine speed at which maximum horsepower is developed.
    Peaked
    A body panel having raised beading for a styling effect.
    Pearlescent Paint
    A color paint with fine mica particles blended into the pigment.
    Pedal Clearance
    The amount of downward brake-pedal movement, 1/4 inch (6.35 mm) or so, before the pushrod contacts the piston.
    Pedal to the Metal
    The accelerator pedal pressed all the way to the floor.
    Peel
    To leave streaks of rubber on the pavement during hard acceleration.
    Peel Rubber
    A term used for lay rubber; the same as to peel.
    Peel Test
    A destructive method of testing that mechanically separates a lap joint by peeling it.
    Peen
    To shape metal by pounding it.
    The ball-shaped end of a hammer head.
    Peg
    A pin at the top end of a speedometer or tachometer to prevent instrument damage.
    The highest possible reading on a speedometer.
    PEL
    An abbreviation for permissible exposure limit.
    Pellet Thermostat
    An engine-coolant thermostat having a wax pellet as a power element, which grows when heated and shrinks when cooled, connected through a piston to a valve.
    Pellet-Bed Catalytic Converter
    A General Motors catalytic converter design having a stainless steel shell and a bed of catalyst-coated ceramic pellets that can be replaced using special vibrator/aspirator equipment.
    Pen
    To draw or design.
    PERA
    An abbreviation for Production Engine Remanufactures Association.
    Percent
    The ratio of one material to another in a mixture as in a fuel mixture.
    Percent of Grade
    A value that is determined by dividing the height of a hill by its length, often used to determine the power requirements of trucks or for determining maximum pay load.
    Percolation
    A condition in which the fuel-bowl vent fails to open when the engine is turned off and internal pressure forces raw fuel through the main jets into the manifold.
    Performance Chart
    A chart that has been produced from a dynamometer showing the horsepower, torque, and fuel consumption of an engine at various speeds.
    Performance Test
    Readings of the temperature and pressure, under controlled conditions, to determine if an air-conditioning system is operating at full efficiency.
    A test to determine if a system or sub-system is performing at maximum efficiency.
    Perimeter Frame
    A conventional chassis frame design that is similar in construction to a ladder frame, having full-length side rails that support the body at its greatest width, providing optimum protection to passengers in the event of a side impact.
    Permanent Magnet
    A piece of ferrous material, such as steel, that retains its magnetic properties without the use of an electric current.
    Permanent Strainer
    A device generally of a Y-configuration having an accessible cylindrical strainer element used in horizontal and vertical lines. The element, retained by a plug end which may be plain or fitted with a valve, can be opened for blow-through cleaning.
    Permatex
    A tradename for a brand of engine and transmission sealants.
    Permissible Exposure Limit (PEL)
    The maximum length of time a person should be exposed to a hazard or hazardous material established by OSHA and expressed as a time-weighted average limit or ceiling exposure limit.
    Petcock
    A small faucet-like valve used for draining liquids, such as that found at the bottom of some radiators.
    Petroleum
    The crude oil from which gasoline, lubricant, and other such products are manufactured.
    PH Level
    A measure of the acidity or alkalinity of a solution on a scale where pH0 is most acid, pH14 is most alkaline, and pH7 is neutral.
    Phaeton
    A four or five passenger, two- or four-door, open-body style that was most popular in the 1920s and 1930s.
    Phosgene Gas
    A highly toxic gas, carbonyl chloride (CCOCl2). Until recently, it was believed that phosgene gas was produced when CFC refrigerants, such as R-12, came into contact with heated metal or an open flame. It is now known that little or none of this gas is produced in this manner.
    Phosphor Bronze
    A hard, tough alloy of copper (Cu), lead (Pb), tin (Sn), and phosphorus (P) low in friction and resistant to wear.
    Phosphoric Acid
    A colorless and odorless acid (H3PO4) used to remove rust from steel and cast iron.
    Photochemical Smog
    A noxious, unhealthy gaseous compound in the atmosphere, formed by the interaction of various chemicals such as the pollutants hydrocarbons (HC) and oxides of nitrogen (NOX) in the presence of sunlight.
    Photovoltaic Diode
    A device having a junction of two dissimilar metals that produces an electrical signal proportional to the amount of light that strikes it.
    Physical Hazards
    Any personal hazards, such as excessive noise, temperature, pressure, and rotating equipment.
    Physical Properties
    Properties that pertain to the physics of a material, such as melting point, density, electrical and thermal conductivity, specific heat, and coefficient of thermal expansion.
    Pickup
    Vehicle acceleration.
    A term used for pickup truck.
    Pickup Coil
    An engine-speed sensor in an electronic ignition system.
    Pickup Truck
    A type of vehicle having an open cargo bed behind an enclosed cab.
    Pickup Tube
    A tube extending from the outlet of the receiver almost to the bottom of the tank to ensure that 100% liquid is supplied to the liquid line or metering device.
    A tube used to transfer fuel or oil from a storage tank.
    Piece Work
    A method of payment whereby a worker receives an agreed fixed amount per piece produced.
    Pig
    An unattractive vehicle.
    A vehicle that is not performing well or as expected.
    A bar of cast metal.
    Pigment
    Small particles added to the paint to influence properties such as color, corrosion resistance, and mechanical strength.
    Pikes Peak
    A 14,110 foot (4,300 meters) high mountain peak in central Colorado where an annual auto-racing hill climb is held around the Fourth of July.
    Pilot
    A driver.
    A device that guides the operation of a machine or part.
    Pilot Bearing
    The bearing at the output end of the engine's crankshaft that supports the transmissions input shaft.
    Pilot Hole
    A small hole drilled into a part to serve as a guide for a larger size drill bit.
    Pilot Model
    The first vehicle of a new design to be constructed on the assembly line to test the assembly procedures and fixtures before full-scale production begins.
    Pilot Operated
    A small valve used to energize or regulate a large valve.
    Pilot Shaft
    A shaft that is used to align parts during assembly.
    Pilot-Operated Absolute (POA)
    A term used for pilot-operated evaporator pressure regulator.
    Pilot-Operated Absolute Suction Throttling Valve (POASTV)
    A term for pilot-operated evaporator pressure regulator.
    Pilot-Operated Evaporator Pressure Regulator (POEPR)
    An evaporator pressure-regulated valve that is regulated by an internal pilot-valve pressure.
    Pin
    An acronym for product identification number.
    Ping
    A mild knock noise from the engine.
    Pinion
    A small gear such as at the end of the steering shaft of a rack-and-pinion steering system.
    A small ring gear such as the planet gears in a planetary gear set.
    Pinion Bearing
    A bearing that is used to support the pinion gear in the differential housing.
    Pinion Gears
    A term used for pinion.
    Pinion Seal
    An oil seal for the pinion gear in a ring and pinion.
    Pinion Shaft
    A shaft used to support a pinion bearing and/or pinion.
    Pink Slip
    A vehicle ownership certificate.
    Pinning
    Using a series of pins to repair a crack in a casting by screwing them into a series of predrilled holes in a manner so that they overlap each other from one end of the crack to the other.
    Pintle
    A valve-like part of a fuel injector that controls the fuel-spray pattern.
    Pintle Hook
    A pin installed in the rear of some vehicles for attaching a tow bar.
    Pintle Valve
    The ball and seat found inside a thermostatic expansion valve, attached to the Diaphragm, which causes it to open and close in response to pressure changes.
    Pipe
    An exhaust system.
    Pipe Brace
    A brace that extends between opposite hangers on a spring or air-type suspension.
    Pipe Dream
    An illusionary fantasy plan, or way of life.
    Pipes
    A dual-exhaust system.
    Piston
    An engine part that reciprocates in the cylinder and transfers the force of the expanding gases via the piston pin and connecting rod to the crankshaft.
    A round, caliper component in a disc brake that is moved outward by fluid pressure to press the pads against each rotor face.
    An aluminum or sintered-iron component of a drum brake inside a wheel cylinder that supports the cylinder cup.
    That part of a compressor that is driven by a crankshaft to compress vapor.
    Piston Boss
    That part of the piston which supports the piston pin.
    Piston Crown
    The top of the piston.
    Piston Displacement
    The cylinder volume displacement by the piston as it travels from the bottom to the top of the cylinder during one complete stroke.
    Piston Markings
    Marks on a piston which are used to identify piston oversize and the front of the piston.
    Piston Material
    Metal used in piston construction, usually cast- or forged-alloy aluminum.
    Piston Oil Ring
    A term used for oil ring.
    Piston Oiler
    A device that injects oil into the piston as an aid to carry away heat from the piston crown.
    Piston Pin
    A round precision-ground part, usually hollow, used to attach the piston to the connecting rod by press fit or held in place with internal snap rings.
    Piston Rings
    Rings that fit into grooves on the outer wall of a piston, just below the crown, that seal the combustion chambers and scrape oil from the cylinder walls.
    Piston Rod
    A plated rod attached to the shock-absorber piston, usually extending from the top of the shock to provide attachment to the vehicle.
    Piston Skirt
    The lower part of the piston that makes contact with the cylinder wall.
    Piston Slap
    The noise that is made by an undersize or loose piston skirt as it makes contact with the cylinder wall.
    Piston Speed
    The velocity of a piston, given in feet per minute, as it reciprocates in a cylinder.
    Piston Stops
    The tabs, or protrusions, on a backing plate so positioned as to prevent the wheel cylinder pistons from leaving the wheel cylinder.
    Piston Temperature
    The temperature of the piston at different areas, varying from over 450°F (232°C) at the crown, to 200°F (93°C) near the bottom of the skirt.
    Piston Valve
    A shock-absorber component used to control the flow of oil and produce the pressure and vacuum in the chamber above the piston during compression and rebound.
    Piston-Pin Bushing
    A bushing that is pressed into the upper end of the connecting rod when free-floating pins are used.
    Piston-Ring Land
    The surface of a piston between ring grooves.
    Piston-Rod Seal
    A non-replaceable oil seal around a movable piston rod, located at the upper end of the hydraulic cylinder.
    Piston-Skirt Clearance
    The allowable space between the piston skirt and cylinder wall, usually 0.001 to 0.002 inch (about 0.025 to 0.051 mm) at room temperature.
    Piston-Skirt Expander
    A device that may be inserted behind the piston skirt to force the skirt out toward the cylinder wall to reduce skirt-to-wall clearance.
    Piston-to-Valve Clearance
    The distance between the intake and exhaust valves and the piston crown when the valves are at overlap period and the piston is at top dead center.
    Pit Crew
    Those responsible for servicing, timing, and the communications of a race car during a race on the track side of the pit wall.
    Those who support the team efforts on the infield side of the pit wall.
    Pit Stop
    A visit to the pits during a race for routine or emergency service or to ask directions.
    Pit Wall
    A wall that divides the pit service facilities on the trackside and infield side.
    Pitch
    The rotating motion of a vehicle's spring mass about its lateral axis, compressing the springs at one end of the vehicle and extending the springs at the other end.
    The uniform spacing of adjacent elements of a series of points, lines, joints, planes, blades, or teeth, as in a broach or gear.
    The center-to-center dimension between chain joints.
    For a sprocket, the dimension between the centers of rollers bedded against the bottoms of adjacent tooth spaces.
    The distance between corresponding points on adjacent threads.
    The angle of setting of some tools.
    The distance from center-to-center of wire in adjacent coils in an open-wound spring.
    Pitman Arm
    Arm attached to the pitman shaft that moves the relay rod as the steering wheel is turned.
    Pits
    The trackside service facilities for servicing vehicles competing in a race.
    Pitting
    Metal-surface irregularities as a result of corrosion.
    Pivot
    A pin or short shaft upon which another part rests or turns, or about which another part rotates or oscillates.
    Pivot Bushing
    A rubber bushing in the front suspension located at the inner end of the control arms where pivoting occurs.
    Pizza Cutters
    The extremely narrow front wheels of a drag-race car used to reduce rolling resistance.
    Pk
    Pink.
    Placard
    A notice for display in a public (obvious) place.
    A label or poster.
    Plain Ends
    End coils of a helical spring having a constant pitch and with the ends not squared.
    Plain Vanilla
    Ordinary and without frills.
    A low-priced economy car.
    Planet Carrier
    The cradle that holds the planet gears in a planetary gear set.
    Planet Pinions
    Small gears that orbit around the sun gear, meshing with and rotating between the sun and internal gears.
    Planetary Carrier
    The framework holding the planetary pinions within the sun gear.
    Planetary Gear Set
    A group of gears named after the solar system because of their arrangement and action. This unit consists of a center (sun) gear around which pinion (planet) gears revolve. The assembly is placed inside a ring gear having internal teeth. All gears mesh constantly. Planetary gear sets may be used to increase or decrease torque and/or obtain neutral, low, intermediate, high, or reverse.
    Planetary Gear System
    A gear set consisting of a central sun gear surrounded by two or more planet gears which are, in turn, meshed with a ring gear, used in overdrives and automatic transmissions.
    Planetary Gear Train
    Gears of the transmission in either the Simpson or Ravigneaux design.
    Planetary Pinion Gears
    Small gears fitted into a framework called the planetary carrier.
    Planing
    A condition that exists when a tire is unable to stay in contact with the ground or pavement due to water. Also known as hydroplaning and aquaplaning.
    Plant It
    To apply full throttle.
    Plasma
    An inert gas used in welding, such as argon or nitrogen.
    Plasma Arc Welding (PAW)
    An arc welding process that uses a constricted arc between a non-consumable electrode and the weld pool (transferred arc) or between the electrode and the constricting nozzle (non-transferred arc) with shielding obtained from the ionized gas issuing from the torch, which may be supplemented by an auxiliary source of shielding gas.
    Plastic Deformation
    A micro-structural change as a result of exceeding the yield point of the material and generally including elongation of the grain structure and increased hardness.
    Plastic Filler
    A two-part, putty-like material that may be used to fill dents in body panels.
    Plastic Gasket Compound
    A plastic paste that is squeezed out of a tube to make a gasket in any shape or configuration.
    Plastic Spring
    A term used for fiber-composite spring.
    Plastigauge
    The tradename for a small, thin, plastic strip that is used to help determine the clearance between main and/or connection rod bearings and the crankshaft journals.
    Plate
    A rectangular sheet of spongy lead in a battery.
    A platform on which an assembly may be mounted.
    Plate Group
    All of the positive plates and all of the negative plates that make up one battery cell.
    Platform
    The basic understructure of a vehicle including all running gear.
    Platinum (Pt)
    A rare, valuable metallic element which is highly resistant to corrosion, and is used as a catalytic agent in automotive catalytic converters of the oxidizing type.
    Plenum
    A chamber containing air under pressure.
    A chamber containing a gas such as air or an air/fuel mixture under higher than atmospheric pressure.
    Plenum Chamber
    An area, filled with air at a pressure that is slightly higher than the surrounding air pressure, such as the chamber just before the blower motor.
    Plenum-Blower Assembly
    Located on the engine side of the firewall, this assembly contains air ducts, air valves, and a blower that permits the selection or air from the outside or inside of the car and directs it to the evaporator or to the heater core if desired.
    Plexiglas
    A brand name of a transparent, lightweight plastic material often used for windows in an enclosed race car.
    Plies
    The cord plies that surround both beads and extend around the inner surface of the tire to enable the tire to carry its load.
    Plow
    A condition in cornering when the slip angles of the front tires are greater than the slip angles of the rear tires and the front end tends to break loose and slide.
    Plug
    A spark plug.
    A threaded, tapered metal pin used to repair cracks in castings, such as an engine block.
    Plug Weld
    A weld made in a circular hole in one member of a joint, fusing that member to another member.
    Plunger
    That part of a hydraulic valve lifter that moves up or down depending on oil pressure.
    Ply Rating (PR)
    A method used to indicate relative tire strength, formerly used to designate the load-carrying capacity of a tire. The ply rating does not necessarily indicate the actual number of plies; a four-ply rated tire, for example, may have two plies but is considered as strong as a standard four-ply tire.
    PM
    An abbreviation for preventative maintenance.
    PMA
    An abbreviation for Professional Mechanics Association.
    PN
    An abbreviation for part number.
    POA
    An abbreviation for pilot-operated absolute, as in a suction throttling valve.
    POA Valve
    A term used for suction throttling valve.
    POASTV
    An abbreviation for pilot-operated absolute suction throttling valve.
    POEPR
    An abbreviation for pilot-operated evaporator pressure regulator.
    Pogo Stick
    The air- and electrical-line support rod mounted behind the cab to keep the lines from dragging between the tractor and trailer.
    Point of Intersection
    Apex of the extended centerline of the pivot axis and the extended centerline of a front wheel.
    Points
    A term used for breaker points.
    Polar Moment of Inertia
    The tendency of a body to resist angular or rotational acceleration.
    The tendency of a vehicle to resist cornering.
    Polarity
    The quality of an electrical circuit or component that determines the direction of current flow.
    Polarizing a Generator
    The correction of the generator-field polarity so it will build up polarity in the proper direction to charge the battery.
    Pole
    The starting position on the inside of the front row in oval-track or road racing.
    Police Options
    A high-performance equipment package available on new cars for law enforcement authorities.
    Police Package
    A term used for police options.
    Polished
    Intake and exhaust passages that have been finished to the smoothest possible surfaces to remove the rough surfaces left by factory casting.
    Pollutant
    Any substance that adds to the pollution of the atmosphere.
    Any substance in the exhaust gas from an engine or evaporating from the fuel tank or carburetor.
    Pollution
    Any gas or substance in the air that makes the air less fit to breathe.
    Excessive noise from machinery or vehicles.
    Poly Alkaline Glycol (PAG)
    The synthetic lubricant of choice in many automotive air conditioners used with HFC-134a refrigerant.
    Poly Ester
    A synthetic lubricant that is used in some HFC-134a air-conditioning systems.
    Poly Lock
    A type of rocker-arm lock nut that is secured with a set screw.
    Polymerization
    A chemical reaction whereby many small molecules combine to form larger, more complex molecules having a higher molecular weight with different chemical properties.
    Polyurethane
    A synthetic material often used as a filter media.
    Poncho
    A Pontiac.
    Ponies
    Horsepower.
    Pony Car
    Any compact, two-door sports car similar to a Mustang.
    Pooch
    A Porsche.
    Pop
    A racing fuel, generally with nitromethane.
    Pop Back
    A condition when the air/fuel mixture is ignited in the intake manifold and may cause a pop back through the carburetor.
    Pop Rivet
    A fastener used to hold two pieces together.
    Pop-Off Valve
    A spring-loaded pressure relief valve.
    Poppet Valve
    An intake or exhaust valve consisting of a disc at the end of a shaft used in a four-stroke cycle engine.
    Porcelain
    A hard, ceramic material as used in spark plugs to insulate the electrode from the shell.
    Porcupine Head
    The cylinder head on a rat motor.
    Port
    A term used for intake port or exhaust port.
    Port Bowl
    The area of the port next to the valve head.
    Port Injection
    A fuel-injection system that injects fuel directly into the individual intake ports.
    Port Runner
    A partition in the intake manifold that directs the air/fuel mixture to the individual cylinders.
    Portable Cable
    An electrical cable used to transmit electrical power to mobile equipment.
    Ported Vacuum
    Engine vacuum, available above the throttle plates of a carburetor, used to advance ignition timing when the throttle is opened above its idle position.
    Ported-Vacuum Switch (PVS)
    A valve which permits or stops the passage of a ported vacuum to a vacuum-operated component, such as a distributor advance mechanism that may be thermostatically operated, or controlled by electric current or the movement of a mechanical component.
    Porting
    To enlarge the intake and exhaust passages.
    Pos-A-Traction
    A brand of tires, tubes, and wheels.
    Posi
    A generic term for a limited-slip differential.
    Posi-Traction
    A limited-slip differential by Chevrolet.
    Position Sensor
    A term used for EGR valve-position sensor.
    Positioned Weld
    A weld made in a joint that has been placed in a position to facilitate making the weld.
    Positive
    One of the two poles of a magnet.
    One of the two terminals of an electrical device, such as a battery.
    Positive Absolute-Suction Throttling Valve
    A suction throttling valve having bronze bellows under a nearly perfect vacuum, which is not affected by atmospheric pressure.
    Positive Back-Pressure EGR Valve
    A common type of exhaust gas recirculation valve which uses exhaust system backpressure to sense engine load, thus more accurately metering the amount of exhaust recycled.
    Positive Camber
    The outward tilt of a wheel on a vehicle.
    Positive Crankcase Ventilation (PCV)
    An engine emissions-control system, operating on engine vacuum, that picks up crankcase gases and meters them into the intake stream to be burned.
    Positive Displacement Pump
    An engine-driven air or liquid pump that displaces the same amount of air or liquid, per revolution, regardless of engine speed.
    Positive Offset
    A wheel rim placed outward of the center of the mounting flange.
    Positive Pole
    The positive terminal of an electrical device.
    The north pole of a magnet.
    Positive Post
    The positive terminal of a battery.
    Positive Terminal
    The terminal to which electrons flow in a complete electrical circuit, often identified by the symbol +.
    Positive Traction
    A limited-slip differential by Buick.
    Positive Wiping Seal
    A seal that maintains constant contact with a stem or shaft to wipe off excess oil.
    Post
    A battery terminal.
    Post Ignition
    Ignition that occurs after the engine-ignition system is shut off, due to carbon buildup in the combustion chamber.
    Post Start
    The time from a cold start to the warm up of an engine.
    Pot
    A carburetor.
    An abbreviation for potentiometer.
    Potential Energy
    Energy of a body or system with respect to the position of the body or the arrangement of the particles of the system.
    Potentiometer (pot)
    A three-wire variable resistor that acts as a voltage divider to produce a continuously variable output signal proportional to a mechanical position.
    Pounds per Horsepower
    The weight of the vehicle divided by its horsepower, a measure of the vehicle's performance.
    Pounds per Square Inch (psi)
    An English measure for pressure or stress.
    Pounds per Square Inch, Absolute (psia)
    An English measure for pressure or stress taken from absolute pressure.
    Pounds per Square Inch, Gauge (psig)
    An English measure for pressure or stress taken from atmospheric pressure.
    Pounds-Feet
    An English measure of torque. One pound (lb) raised one foot (ft) is equal to one pounds-feet (lb-ft).
    Pounds-inch
    An English measure of torque; the energy required to raise one pound, one inch.
    Pour on the Coal
    To accelerate rapidly.
    Pour Point
    The lowest temperature at which a fluid will flow freely.
    Poured Bearings
    Bearings that are formed by first pouring molten babbitt material into the bearing cavity, allowing it to cool, then boring it to a specific size.
    Powder Puff Race
    An auto-racing event strictly for women drivers.
    Power
    A measure of work being done.
    The rate at which work is being done.
    Power Brakes
    A system utilizing energy from the vehicle's engine to reduce the amount of brake-pedal pressure that must be exerted by the driver to stop the car.
    Power Break
    In an automatic transmission-equipped drag racer, the act of holding the brake pedal firmly while revving the engine, then simultaneously releasing the brake while flooring the accelerator to get the quickest possible start.
    Power Cable
    Cable used to supply electrical power (current).
    Power Control Module
    A module or computer used in an electronic transmission to aid in control of the shift solenoids.
    Power Cylinder
    A shell containing the power-brake operating parts.
    Linkage-type steering component attached between the frame and the steering relay rod.
    Power Flow
    The flow of power from the input shaft through one or more sets of gears, or through an automatic transmission to the output shaft.
    Power Hop
    The tendency of an axle housing to rotate slightly with the wheels then snap back during hard acceleration.
    Power Mirror
    Outside mirrors, having reversible permanent-magnet motors, that are electrically positioned from the inside of the driver's compartment.
    Power on/off Watchdog Circuit
    Supplies a reset voltage to the microprocessor in the event that pulsating output signals from the microprocessor are interrupted.
    Power Oversteer
    The loss of traction of the rear wheels while cornering and accelerating, causing the rear of the vehicle to swing toward the outside of the turn.
    Power Piston
    A component acted on by pressurized fluid to assist wheel turning on integral or linkage-type power-steering systems.
    Power Plant
    An engine.
    Power Section
    The section of a gas-turbine engine containing the power turbine rotors which, through reduction gears, turn the wheels of the vehicle.
    Power Servo
    A servo unit used in automatic temperature control which is operated by a vacuum or an electric signal.
    Power Shift
    The rapid forced shifting of a manual transmission without releasing the clutch or accelerator.
    Power Slide
    A controlled four-wheel skid in dirt-track racing to maintain speed through a turn.
    Power Steering
    A power assisted steering system that uses hydraulic pressure to increase the torque (turning effort) applied to the steering wheel by the driver.
    Power Steering fluid
    Special hydraulic fluid formulated to withstand extremely high system pressures and temperatures.
    Power Steering Pump
    A hydraulic pump driven by a belt from a crankshaft pulley to provide up to 1,300 psi (8,964 kPa) boost pressure necessary to operate the power-steering system.
    Power Steering, Integral-Type
    A power-steering system having the power assist mechanism and related controls inside the steering gearbox.
    Power Steering, Linkage-Type
    A power-steering system having the control valve and power cylinder attached to the steering linkage under the car.
    Power Stroke
    The piston stroke, with both valves closed, in which combustion takes place, forcing the piston from TDC to BDC.
    Power Synchronizer
    A device in the transmission that speeds up the rotation of the main-section gearing for smoother automatic downshifts and to slow down the rotation of the main-section gearing for smoother automatic upshifts.
    Power Take Off (PTO)
    An output shaft found on some four-wheel drive vehicles for driving an external accessory, such as a winch.
    Power Team
    The engine, transmission, rear end, and axle combination.
    Power Tools
    Tools that use compressed air (pneumatics), electricity, or hydraulic pressure to generate and multiply the force required to accomplish the work.
    Power Train
    A combination of the engine, transmission, and final drive.
    Power Valve
    A valve in the carburetor that opens during acceleration to increase fuel flow.
    Power-to-Weight Ratio
    The relationship of a vehicle's horsepower to its weight as given in horsepower per pound.
    Ppm
    An abbreviation for parts per million.
    PR
    An abbreviation for ply rating.
    Pre-Cat Converter
    A term used for light-off, mini-oxidation catalytic converter.
    Pre-Ignition
    The ignition of the air/fuel mixture in the combustion chamber by means other than the spark; usually caused by hot spots in the combustion chamber due to sharp edges, carbon accumulation, or spark plugs with a heat range that is too hot.
    Precision Insert Bearing
    Bearings that may be installed in an engine without having to be bored, reamed, honed, or ground.
    Precombustion Chamber
    A second combustion chamber placed directly off the main combustion chamber, used to ignite a rich mixture of air and fuel which then ignites a lean mixture in the main combustion chamber.
    Predelivery Inspection (PDI)
    The process of inspecting, adjusting, and fine tuning a new car prior to delivery to the customer.
    Preformed Radiator hose
    A large-diameter hose connecting the radiator to the engine cooling system that is molded in the proper shape to fit on a certain engine.
    Preheater
    A glow plug that is used to heat the precombustion chamber of a diesel engine before it is started.
    Preheating
    Heating the weld area of a metal before welding, to avoid thermal shock and stress.
    Preload
    The transfer of weight from one side of a vehicle to the other to compensate for the lateral weight transfer that occurs when cornering.
    The pressure applied to a part during assembly or installation.
    Prelube
    To apply lubricant to the parts of a rebuilt engine before starting it up.
    Prerun
    To examine and appraise an off-road race route.
    To test a rebuilt engine before installing it in the vehicle.
    Prerunner
    A vehicle that is built to be used to examine and evaluate the off-road route of an upcoming race.
    A vehicle often used as an off-road race-chase vehicle for parts, fuel, and other supplies.
    Press Fit
    The fitting of two parts with very close tolerances, one inside the other, generally by using a hydraulic press. Also known as force fit.
    Pressure
    Force per unit area or force divided by area, usually expressed in psi, psig, or psia (kPa or kPa absolute).
    Pressure Balancing Ring
    A compression ring having a ceramic coating to ensure sealing against the cylinder wall.
    Pressure Bleeder
    A device used to facilitate the removal of air from the brake system.
    Pressure Bleeding
    Bleeding the brake system using a pressure bleeder to charge the system.
    Pressure Cap
    A cap placed on the radiator to increase the pressure of the cooling system, reduce cavitation, protect the radiator hoses, and prevent or reduce surging.
    Pressure Connector
    A connector applied using pressure to form a cold weld between the two parts.
    Pressure Control Valve
    A device used to control and regulate the pressure of a system or sub-system.
    Pressure Differential Valve
    A valve used in a dual-brake system to turn on a dash warning light if the pressure drops in either part of the system.
    Pressure Drop
    The loss of pressure due to a restriction, a long line, or a small diameter line.
    Pressure Hold
    One condition in an anti-lock brake control module in which no more braking pressure can be produced in the master cylinder.
    Pressure Hose
    A special, reinforced high-pressure hose through which pressurized fluid flows.
    Pressure Line
    A term that generally refers to the discharge line of an air-conditioning system.
    A term that may apply to brake or power-steering hoses.
    Pressure Plate
    That part of a manual clutch that is mounted on and rotates with the flywheel and exerts pressure against the friction disk.
    Pressure Plate assembly
    An assembly of various parts that operate to press the clutch disc against the flywheel, engaging power flow to the clutch shaft, or release the disc, disengaging power flow.
    Pressure Reduction
    A drop of pressure due to a restriction or metering device.
    Pressure Regulator
    A device that operates to prevent excess pressure buildup in a system.
    A valve in some automatic transmissions that opens to release oil from a line when the oil pressure reaches a specific maximum limit.
    Pressure Release Grill
    An air vent that prevents pressure from building up inside the car while the air-conditioning system is operating.
    Pressure Relief Groove
    A small groove cut in the piston-ring land between the grooves for the compression and oil rings to equalize combustion pressures between them.
    Pressure Relief Valve
    A valve held closed by a spring or other means, which automatically relieves pressure in excess of its setting.
    A carburetor fuel bowl vent operated by vapor pressure from evaporated fuel.
    An air-injection system valve that functions to relieve pump-output pressure that exceeds a predetermined amount, usually at speeds over 45 mph (72.4 km/hr).
    A special valve in an engine lubricating system having a calibrated spring working against a moveable plunger or ball to regulate maximum oil pressure.
    Pressure Test
    A procedure for testing the entire cooling system for leaks.
    Pressure Tester
    A device used to pressure test the cooling system and pressure cap.
    Pressure-Fed Oil System
    A type of lubrication system that uses an oil pump to force oil to the various parts of an engine.
    Pressurize
    To apply more than atmospheric pressure to a device or system.
    Pressurized Carburetor
    A carburetor on a turbocharged engine that mixes fuel with air under pressure from the turbo.
    Prevailing Torque Nut
    A nut designed to develop an interference fit between the nut and bolt threads.
    Preventative Maintenance (PM)
    A systematic and scheduled inspection and service of a vehicle to ensure proper maintenance to provide a standard for satisfactory and sound operational conditions.
    Price Guides
    A reference that is used to determine a proper fee for repair labor based on time.
    A reference providing the value of used vehicles based on geographic location, condition, and accessories.
    Primary
    The low-voltage circuit of an ignition system.
    Primary Brake Shoe
    The brake shoe in a set which initiates self-energizing action.
    Primary Circuit
    The electrical circuit of the low-voltage winding of an ignition coil.2. The main fuel passages in a carburetor.
    Primary Damage
    The damage caused by the initial impact of a collision.
    Primary Resistance
    A calibrated resistance wire or ballast resistor in a conventional ignition system inserted between the ignition switch and coil to reduce the primary voltage at low engine speeds.
    Primary Seal
    A seal between the compressor shaft seal and the shaft to prevent the leakage of refrigerant and oil.
    Primary Shoe
    The brake shoe toward the front of the vehicle in a dual-servo drum brake having a lining that may be shorter, thinner, and have different frictional characteristics from the secondary shoe.
    Primary Winding
    The outer, low-voltage winding of an ignition coil.
    Primer
    A type of paint applied to a surface to increase its compatibility with the topcoat or to improve the corrosion resistance of the substrate.
    Primer Sealer
    A type of paint that provides adhesion for the topcoat and seals old, painted surfaces.
    Primer Surfacer
    A type of paint having a high-solids content which fills small imperfections in body work and which usually must be sanded.
    Priming Spring
    A coil spring that holds the movable slide in the maximum position in a vane-type pump.
    Prindle
    The standardized shift pattern for an automatic transmission, PRNDL.
    Printed Circuit
    An electrical circuit made by applying a conductive material to a printed circuit board.
    Printed Circuit Board
    A thin, insulating board used to mount and connect various electronic components, such as resistors, diodes, switches, capacitors, and microchips in a pattern of conductive lines.
    PRNDL
    The shift pattern for many automatic transmissions.
    Pro Stock
    A category for compact, passenger drag-racing cars with a big block V-8 engine having a maximum of 500 cubic inches (8.2 liters).
    Pro Street
    A compact passenger car with a modified V-8 engine and rear drive built for street use.
    PROCO
    An abbreviation for programmed combustion.
    Production Engine Remanufactures Association (PERA)
    A trade association of those who rebuild gasoline and diesel engines or manufacture and/or distribute engine parts and engine rebuilding equipment.
    Professional Mechanics Association (PMA)
    An association of professional mechanics that offers members savings on tools, travel, insurance, training, equipment, and shoes.
    Profile
    A term used for aspect ratio and tire profile.
    Program for Alternative Fluorocarbon Toxicity (PAFT) Testing
    A testing agency founded by refrigerant manufacturers for the purpose of study and testing of new purpose of study and testing of new refrigerants to determine toxicity levels.
    Program for European Traffic with Highest Efficiency and Unprecedented Safety (Prometheus)
    A research and development effort by major European auto makers for the purpose of studying if telecommunications technology can improve the efficiency and safety of European roads.
    Programmable Read-only Memory (PROM)
    A read-only memory chip that can be programmed by electrical pulses.
    Programmed Combustion (PROCO)
    A research type of stratified charge engine developed by Ford.
    Programmed Protection System
    A bypass valve system to protect the catalyst and their containers from being destroyed due to overheating conditions that may be caused by certain modes of operation or from an engine malfunction.
    Progressive Linkage
    A carburetor linkage system used on multiple carburetors to progressively open the secondary circuits.
    Progressive-Rate Spring
    A spring used in a vehicle that stiffens under load.
    PROM
    An acronym for programmable read-only memory.
    Prometheus
    An abbreviation for Program for European Traffic with Highest Efficiency and Unprecedented Safety.
    Prony Brake
    A machine for testing the power of an engine while running against a friction brake.
    Proof Loading
    Subjecting chain to a tensile loading of some predetermined percentage of the chain's rated strength.
    Propane
    A combustible, liquefied petroleum gas (C3H8) that becomes a liquid when compressed.
    Propane Enrichment
    A service procedure used to set idle mixture where a metered amount of propane gas is added to the intake stream and a resulting rpm increase is observed.
    Propeller Shaft
    A term used for drive shaft.
    A hollow, steel shaft that connects the transmission output shaft to the differential drive pinion yoke through universal joints at each shaft end.
    Property Class
    A number stamped on the end of a metric bolt to indicate the hardness of the bolt.
    Proportioning Valve
    A valve in the brake hydraulic system that reduces pressure to the rear wheels to achieve better brake balance.
    Protective Atmosphere
    A gas or vacuum envelope surrounding the work pieces, used to prevent or reduce the formation of oxides and other detrimental surface substances, and to facilitate their removal.
    Protective Tube
    A shock absorber component used to keep dirt and road dust away from the seals and piston rod.
    Protest
    To object to a rule or conditions prior to the competition.
    To accuse a competitor of a rules violation after a race competition.
    Proto
    An abbreviation for prototype.
    Proton
    A positively-charged particle in the nucleus of an atom.
    Prototype (Proto)
    An individually built test version of a new design of a car or system.
    An individually built vehicle in sports-car racing when an insufficient number of vehicles have been manufactured to be placed in a category.
    Prove-out Circuit
    A function of the ignition switch that completes the warning light circuit to ground when it is in the START position, so the warning lights will be on during engine cranking to indicate to the driver that the bulbs are working properly.
    Proximity Effect
    The distortion of current density due to magnetic fields increased by conductor diameter, close spacing, frequency, and magnetic materials such as steel conduit or beams.
    Prussian Blue
    A blue pigment in solution applied to the surface area used to determine the contact area between two mating surfaces.
    Psi
    An abbreviation for pounds per square inch.
    Psia
    An abbreviation for pounds per square inch, absolute.
    Psig
    An abbreviation for pounds per square inch, gauge.
    Psych
    To intimidate a competitor in competition.
    PTO
    An abbreviation for power take off.
    Puck
    A brake pad.
    A valve-adjusting shim.
    Puffer
    A supercharger.
    Pull
    A condition whereby the vehicle veers to one side or the other when the brakes are applied.
    Pull Circuit
    A circuit that brings a tractor cab from a fully tilted position up and over the center.
    Pull Rod
    A body-working tool in which the curved end of the rod is inserted in the drilled hole to pull out dents.
    Pull-Type Clutch
    A type of clutch whereby the release bearing is pulled toward the transmission.
    Pulldown
    A term used for pumpdown.
    Pulley
    A wheel-shaped, belt-driven device used to drive engine accessories.
    Pulsation
    A surge that may be felt in the brake pedal during low-pressure braking.
    Pulse Period
    A term used for pulse width.
    Pulse Ring
    A ring on the crankshaft to trigger a sensor used with an onboard computer to control ignition timing.
    Pulse Time
    A term used for pulse width.
    Pulse Width
    The time, in milliseconds, the injectors are energized and held open, which determines the amount of fuel injected. Also known as pulse period and pulse time.
    Pulse-Delay Variable Resistor
    A resistor in the electrical circuit of the wiper system used to delay the wiper motion from 0 to 25 seconds.
    Pulsed Air System
    A shortened term for pulsed air-injection system.
    Pulsed Air-Injection System
    A device found in the exhaust emission system that injects pulses of ambient air into the exhaust as an aid in the burning of exhaust gases.
    Pump
    A device that transfers gas or liquid from one place to another.
    Pump Air Bleed
    In a fuel-supply system, small vent holes in the mechanical fuel-pump body that allow air to enter and leave the pump as the Diaphragm moves back and forth.
    Pump Impeller
    That part of a fluid pump that causes the fluid to move.
    The output drive member that receives its power from the engine.
    Pump Link
    In a fuel-supply system, a short, connecting part between the pump rocker arm and the Diaphragm on certain models.
    Pump Reservoir
    A container located on or adjacent to the pump, providing fluid and reserve for proper system operation.
    Pump Rotors
    Parts of a positive displacement pump that uses rotating rotors to develop flow.
    Pump Screen
    A filter to remove debris from a fluid before it enters the pump.
    Pump Up
    A condition where a hydraulic-valve lifter has developed more pressure than required and prevents the valve from seating properly.
    Pumpdown
    A term used for evacuate, as in an air-conditioning system. Also known as pulldown.
    Pumping Brakes
    A term that refers to the practice of depressing the brake pedal several times in quick succession.
    Punch
    A racing fuel, generally with nitromethane.
    Punch It
    To apply full throttle.
    A term used for plant it or punch off.
    Punch Off
    A term used for punch it or plant it.
    Puncture-Sealing Tire
    A specialty tire made to permanently seal tread punctures up to 3/16 inch (4.76 mm) in diameter with a resultant rubber-compound sealer applied to the inside of the tire by the manufacturer.
    Pup Converter
    A term used for light-off, mini-oxidation catalytic converter.
    Pur Sang
    A french term for pure blood used to describe a particularly fine car.
    Pure Stock
    A vehicle that conforms to all original factory specifications.
    Purge
    To remove moisture and/or air from a system or a component by flushing with a dry gas, such as nitrogen (N).
    To remove all refrigerant from an air-conditioning system.
    Purge Valve
    A valve in some evaporative emission-control system charcoal canisters to limit the flow of vapor and air to the carburetor during idle.
    Purity Test
    A static test that may be performed to compare a suspect refrigerant pressure to an appropriate temperature chart to determine its purity.
    Push
    A condition in cornering when the slip angle of the front tires is greater than the slip angle of the rear tires and the front end of the vehicle tends to break loose and slide toward the outside of the turn.
    Push Angle
    The travel angle when the electrode is pointing in the direction of weld progression.
    Also used to partially define the position of guns, torches, rods, and beams.
    Push Bar
    A bar in the front of a push car to prevent damage to either vehicle when push-starting a race car.
    Push Car
    Usually a truck; a vehicle used to push start a race car.
    Push Circuit
    A circuit that raises a tractor cab from the lowered position to the desired tilt position.
    Push Start
    To start a vehicle by pushing it with another.
    Push-Type Clutch
    A type of clutch in which the release bearing is not attached to the clutch cover.
    Pusher
    A rear-engine vehicle.
    Pushrod
    A solid or hollow rod which serves as a link between the valve lifter and rocker arm.
    The rod that transmits the movement and force of the driver from the brake pedal lever to the master cylinder.3. The rod that transmits the movement and force of the wheel cylinder piston to the brake shoe.
    Pushrod Tube
    The passage from the engine block to the cylinder head that contains a pushrod.
    Put on the Trailer
    To decisively defeat a racing competitor.
    Put to the Wood
    A term for applying full throttle.
    Putter
    A custom car that is not intended for high performance.
    Putty
    Body filler.
    PVC valve
    A valve used in positive crankcase ventilation systems to meter blowby into the intake stream.
    PVS
    An abbreviation for ported-vacuum switch.
    Pyroconductivity
    Electric conductivity that develops with changing temperature, and notably upon fusion in solids that are practically nonconductive at atmospheric temperatures.
    Pyrolysis
    The decomposition of a compound due to its exposure to high heat.
    Pyrolytic Oven
    An oven used to remove grease, oil, and rust from the surfaces of engine parts.
    Pyrometer
    An instrument used to measure high temperature.
    Pyrophoric
    A substance having the quality of spontaneous ignition when exposed to air.
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