automotive diagrams

7/30/2019 Automotive Diagrams

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AUTOMOTIVE DIAGRAMS

Engine

The engine is a mechanical device designed to convert chemical energy (fuel) into kinetic energy (motion), which powers your vehicle.

Almost all vehicles (including hybrids) use internal combustion engines that burn fuel. In an internal combustion engine, air and fuel are ignited

inside a cylinder and the pressure that is created forces pistons to move up and down. This rotates the crankshaft, which del ivers power to the wheels

via the drivetrain.

Piston

A piston is a cylindrical piece of metal that moves up and down inside each cylinder, compressing the air-fuel mixture and capturing the force created

by the combustion process. This force is then transferred to the crankshaft, via the connecting rod.More >>
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Crankshaft

The crankshaft is a long, steel shaft that transfers the up-and-down motion of the pistons and connecting rods into rotational motion.More >>

Related Systems

Ignition System

The ignition system supplies the "spark" to each cylinder, which is necessary to begin the combustion process.

Ignition systems have evolved from using a mechanical distributor and special wires to transmit the spark from the ignition coil to each spark plug, to

a fully electronic system which has an ignition coil mounted directly on top of each spark plug. Routine maintenance has been reduced from a "tune-

up" every 12,000 miles to simply replacing the spark plugs every 100,000 miles.

Fuel System

The fuel system provides the fuel necessary for the engine to operate.

In years past, a mechanical fuel pump and carburetor were used. In order for engines to run better and produce less harmful emissions, electronic fuel

injection systems have taken their place. On modern vehicles, fuel is supplied by an electric pump and metered to the cylinders by computer

controlled fuel injectors.
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Engine Cooling System

The cooling system helps regulate the amount of heat in the engine. If its too hot, the engine can overheat. If its too cold, the engine emits more

pollutants and engine components prematurely wear out. If the cooling system fails to keep the engine at the right temperature, it can suffer

significant damage and, in some cases, fail entirely.


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Air Filter

In order to run, the engine needs a precise mixture of fuel and air. When outside air is drawn into the engine, the air filter prevents harmful dirt and

debris from entering the system.

Symptoms of Wear or Failure

Poor gas mileage

Reduced engine power

Related Repair Advice

The air filter should be inspected, cleaned, and/or replaced every 12,000 to 15,000 miles

When replacing the air filter, dirt and debris should be removed from the air filter housing

If oil has contaminated the air filter, it should be replaced; oil contamination may indicate a problem with the PCV system

Air filters will need to be replaced more often in vehicles driven in dusty and sandy areas


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Coolant

Coolant is the fluid that flows through the engines cooling system. Its main purpose is to transfer heat generated by the engine to the radiator so the

engine doesnt overheat.


Temperature gauge may read very high

Engine overheating

Low coolant warning light may illuminate

Dirty or smelly coolant indicates that a system flush may be needed


Over time, coolant gets dirty and breaks down; it should be replaced following the manufacturer's recommendation

Make sure to use the coolant the manufacturer recommends; the wrong coolant can damage your vehicle

A pressure check of the cooling system should be performed to determine where a coolant leak is originating. After repairs, the system should bepressure tested again to verify that the repair is successful.

If you have a problem with the coolant level dropping, but no signs of an external leak, the issue may be an internal engine leak. This type of leakmay be due to a leaking intake manifold gasket, head gasket, or oil cooler. A shop will need to conduct various tests to find these types of leaks.

After the cooling system has been serviced or repaired, it's important to verify that the system is not leaking, the radiator fans are operating properly,and all air bubbles and air pockets are bled from the cooling system.

To help prevent future issues, we recommend replacing the thermostat when the cooling system has been opened for repairs (e.g. water pump orradiator replacement) or during a system flush


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Crankshaft

The crankshaft is a long, steel shaft that transfers the up-and-down motion of the pistons and connecting rods into rotational motion.


Knocking noise from engine

Low engine oil pressure


If a crankshaft or connecting rod bearing fails, the crankshaft should be thoroughly inspected before reuse

In some cases, a failed crankshaft can be repaired or replaced. However, on higher mileage vehicles, engine replacement is often recommended.


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Camshaft

Driven by the crankshaft, the camshaft has multiple elliptical lobes (cams), one for each intake and exhaust valve contained in the engine. As the

camshaft rotates, the lobes regulate the opening and closing of the valves.


Abnormal noise from the valve train

Engine misfires


The camshaft oil seals should be inspected and replaced as necessary when the timing belt is replaced


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Crankcase

Mounted between the engine block and the oil pan, the crankcase supports the crankshaft, allowing it to spin freely while transmitting power (torque)

from the engine.


Engine oil leak

Knocking noise from engine


Engine-specific oil sealing procedures must be employed when installing the crankcase


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Cylinder Head

Mounted to the top of the engine block, the cylinder head houses the intake and exhaust valves, as well as the spark plugs.


Engine misfire

Engine overheating

Excessive oil consumption


The cylinder head mounting surface should be thoroughly inspected when replacing the head gasket

To avoid damage to the cylinder head, manufacturer's recommendations should be followed when removing spark plugs from an aluminum cylinderhead


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Drive Belt/Fan Belt

These belts can be used individually or grouped together as part of the belt/pulley system that is driven by the engine crankshaft to run such items as

the air conditioning compressor, alternator, and power steering pump.


Belts may become dry, cracked, or glazed

Belts may emit a chirping or squeaking sound


On older vehicles, belts with a V" profile were the universal drive belt design, but more modern vehicles use the flat "ribbed" design

The term "serpentine belt" referrers to a ribbed belt that drives multiple accessories.

For optimal performance and reliability, belts should be replaced at the interval recommended by the manufacturer. We recommend replacing all ofthe drive belts as a set, so that they wear evenly.

We recommend replacing drive belts if related components are being repaired and the belts have signs of wear or have over 30,000 miles on them

High-quality drive belts are less likely to squeak and/or prematurely fail

Leaking valve cover gaskets can cause premature drive belt failure. Engine oil will damage even a new belt.

A water pump will require replacement if it begins to leak coolant or become noisy. Leaking coolant can damage the drive and timing belts.


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Engine Block

The engine block is the main body of the engine assembly. It contains the cylinders that accommodate pistons and connecting rods.


Abnormal knocking or rattling noise

Engine oil leak


Engine replacement is often recommend when problems are encountered with the engine block

A "short block" replacement may also be recommendedthis replacement only includes the lower parts of the engine and leaves out the cylinderhead and intake manifold


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Engine Cylinder

Engine cylinders are machined round bores (tubes) inside the engine block that house the pistons. As the engine operates, the pistons move up and

down within the cylinders.


Engine misfire


Engine overheating


Engine replacement is often recommend when problems are encountered with a cylinder


The cylinders may be machined inserts (sleeves) that are fit into the engine block or cast and machined as an integral part of the engine block


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Head Gasket

The head gasket creates a working seal between the cylinder head and the engine block.


Check Engine Light may illuminate

Engine runs roughly when first started

Engine overheating

White, sweet smelling smoke from exhaust

Coolant or oil leak


Head gasket failures are often due to an overheated engine, but can also be caused by high mileage and/or age

If the head gasket(s) is replaced, the cylinder head(s) will need to be inspected and machined. Additional repairs may be needed after the inspection,which can add several hundred dollars to the repair.

To prevent an expensive, recurring problem, the integrity of the entire cooling system should be inspected and tested when a head gasket is replaced.Due to the damaging effects of coolant entering the combustion chamber, oxygen sensor and/or catalytic converter replacement may be prudent or

even necessary. This is especially true if head gasket failure was severe or prolonged.


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Lower Radiator Hose

After the radiator has cooled the coolant, the lower radiator hose carries it from the radiator back to the engine.


Coolant leak

Temperature gauge may run high

Engine overheating


Radiator hoses, like all hoses, should be checked periodically for cracks and swelling. Being constructed of rubber, they are susceptible to dry rot andcracking as they age, and also deteriorate when they come into contact with oil.

The entire cooling system should be inspected when replacing coolant hoses. If any other hoses or cooling system parts show signs of wear, theyshould be replaced at this time.

We recommend replacing the hose clamps when the hoses are replaced, as the clamps will weaken over time and new clamps will help preventcoolant leaks



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Upper Radiator Hose

The upper radiator hose carries hot coolant from the engine into the radiator for cooling.


Coolant leak

Temperature gauge may run high

Engine overheating


As hot engine coolant leaves the thermostat housing, it first contacts the upper radiator hose. This added stress makes the upper radiator hose themost common coolant hose to fail.

Radiator hoses, like all hoses, should be checked periodically for cracks and swelling. Being constructed of rubber, they are susceptible to dry rot andcracking as they age. They also deteriorate when they come into contact with oil.

The entire cooling system should be inspected when replacing coolant hoses. If any other hoses or cooling system parts show signs of wear, theyshould be replaced at this time.

We recommend replacing the hose clamps when the hoses are replaced, as the clamps will weaken over time and new clamps will help preventcoolant leaks



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Oil Filter

The engine oil filter removes contaminants from the engine oil before it circulates throughout the engine.


Abnormal knocking noise from engine

Engine oil leak


Manufacturers differ in their recommended guidelines for when engine oil and oil filters should be changed. As a general rule, however, engine oilshould be changed every 3,000 miles to keep the engine healthy and to prolong its life.

We recommend using a high-quality engine oil filter. Cheap filters wear more quickly and may not properly keep contaminants out of the engine.

We recommend replacing the drain plug gasket along with the oil and oil filter


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Oil Pan

Mounted to the bottom of the crankcase, the oil pan is a reservoir where engine oil is stored and drawn from.


Oil may leak onto the ground and be seen on the underside of the vehicle


The oil pan is sealed with a gasket, which can be made of paper, rubber, or a sealing liquid (liquid gasket)

Some engines have an upper and lower oil pan gasket; the upper oil pan may also be referred to as the crankcase

The oil pan is on the bottom of the engine, so any oil leaks from the top or front of the engine could drain down and look like an oil pan leak. It'simportant to verify that there are no other leaks before having the oil pan resealed.

Over-tightening of the oil drain plug can damage the oil pan threads, requiring replacement of the oil pan


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Oil Pan Gasket

The oil pan gasket is the working seal between the oil pan and the lower part of the engine.


Engine oil leak


The oil pan gasket can be made of paper, rubber, or a sealing liquid (liquid gasket)

Some engines have an upper and lower oil pan gasket; the upper oil pan may also be referred to as the crankcase

The oil pan is on the bottom of the engine, so any oil leaks from the top or front of the engine could drain down and look like an oil pan leak. It'simportant to verify that there are no other leaks before having the oil pan resealed.


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Oil Drain Plug Gasket

The oil drain plug gasket seals the oil drain plug where it connects to the oil pan.


Engine oil leak


The oil drain plug gasket is commonly inspected and replaced when the engine oil is changed


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Oil Pump

The oil pump creates the pressure necessary to circulate oil throughout the engine.


Oil light may come on or engine oil pressure gauge will read low

The engine may make loud clicking or knocking noises


Low oil pressure can be caused by using the incorrect type of engine oil. Be sure to check with your owner's manual to ascertain the correct type foryour engine and climate.

The oil pressure should be checked before condemning an oil pump. A good quality repair shop will perform an oil pressure check and record thereadings on the repair order.

Low oil pressure can be caused by a plugged oil pick-up screen, leaking seals, or worn bearings in the engine. It is important that these items areinspected before replacing the oil pump.

If the oil pump is located in the engine oil pan, the pan must be removed to replace it

If the oil pump is driven directly by the crankshaft, the accessory belts, timing cover, timing belt, and crankshaft pulley must be removed in order toaccess the oil pump


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PCV Filter

The positive crankcase ventilation (PCV) filter, or crankcase emission filter, is connected to the fresh air side of the PCV system. Its purpose is to

filter outside air before it enters the engine crankcase.


Accumulation of dirt on filter


PCV filters should be inspected whenever the PCV system or air filter is serviced

PCV Hose

The positive crankcase ventilation (PCV) hose carries crankcase gases from the engine to the intake manifold, where they are drawn into the

cylinders for combustion.


Engine vacuum leak

Rough or high engine idle

Illumination of the Check Engine Light


The PCV hose should be inspected whenever the PCV system is serviced

PCV Valve


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The positive crankcase ventilation (PCV) valve controls the pressure of accumulating gases in the engine crankcase by venting them back into the

intake manifold.


Engine may run rough or stall


Engine oil leak

High emission levels



The PCV valve should be replaced every 30,000 to 50,000 miles

The engine should be tested to verify normal operation after a PCV repair. This is to ensure that no additional problems exist that may havecontributed to PCV failure.

A plugged PCV system can cause engine oil leaks. It's important that the shop checks and eliminates any issues with the PCV system while repairingengine oil leaks.


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Piston

A piston is a cylindrical piece of metal that moves up and down inside each cylinder, compressing the air-fuel mixture and capturing the force created

by the combustion process. This force is then transferred to the crankshaft, via the connecting rod.


Engine misfire


Knocking or slapping noise from inside engine


A failed piston can cause internal engine damage; the engine might need to be replaced



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Radiator

The radiator's job is to allow heat to be removed from the engine. As hot coolant passes through the radiator it is cooled before returning to the

engine, where it absorbs heat and returns to the radiator. This cooling process keeps the engine from overheating.


Coolant may leak or boil over

Temperature gauge may get really high

Illumination of the engine temperature warning light

Engine may run hot or overheat


We recommend replacing the thermostat and the radiator cap along with the radiator. The radiator hoses should also be replaced if they show signs ofage or wear.

The entire cooling system should be inspected and tested when the radiator is replaced

Most radiators are made of metal and plastic. The plastic parts can become brittle and crack over time, leading to radiator replacement.

Removal of the front bumper, as well as removal of engine bay components such as hoses, ducting, and additional plumbing, are often required in thecourse of this repair


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Radiator Fan Assembly

The radiator fan assembly, which helps to cool the hot coolant in the radiator, is comprised of cooling fan(s), cooling fan motor(s), and a fan shroud.


Fan may become noisy

Engine may overheat, especially when idling and driving in traffic

A/C may perform poorly, especially when idling and in stop-and-go traffic


If a new fan assembly is required, the engine may have been overheated and should be checked for damage before replacing the fan

If only some parts of the fan assembly are replaced, those that are not should be thoroughly inspected to make sure they are still in good shape. If not,the parts should be replaced, too.

Radiator Cap

The radiator cap seals the main filling point of the cooling system. It also allows a set pressure to build in the system, which increases the boiling

pointand thus, the efficiencyof the cooling system.


Coolant may leak or boil over

Temperature gauge may get really high

Illumination of the engine temperature warning light

Engine may run hot or overheat


The term "radiator cap" refers to the cap that regulates the coolant pressure in the cooling system. Standard pressure is usu ally 14 to 16psi.

The cooling may have multiple "radiator caps" located at the various fill points

Whenever the cooling system is serviced for any reason, the radiator cap(s) should be inspected and replaced as necessary

Be very cautious when removing the radiator cap. Don't remove the cap when the engine is hot.


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Spark Plug

The spark plug uses the energy produced by the ignition coil to generate the spark necessary to ignite the air/fuel mixture in the combustion chamber.


Check Engine Light may come on or blink

Engine may run roughly

Abnormal engine noise due to loose or missing spark plug


Failing spark plugs can cause the engine to run rough and misfire, which can trigger the Check Engine Light. Continuing to dr ive under theseconditions can damage the catalytic converter.

Engines may have one or two spark plugs per cylinder and each spark plug can have from one to four electrodes

Replacing spark plugs can be labor intensive on some late model vehicles

To prevent ignition misfires and Check Engine Light problems, we recommend using only high-quality spark plugs, and preferably spark plugs fromthe OEM

Spark plugs have different ratings and it's important that the correct type are used

Spark plug terminals wear down over time and can lead to engine misfires. At a minimum, they need to be replaced at the mileage specified by thevehicle manufacturer.

Manufacturer's instructions should be followed when removing spark plugs. Cylinder heads made from aluminum can be damaged if the correctprocedures are not followed.


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Thermostat

The thermostat is a mechanical device that controls engine temperature. It blocks coolant flow to the radiator until the engine reaches a

predetermined temperature. This allows the engine to warm up quickly and efficiently.


Thermostat housing may leak coolant

Engine may overheat or never reach normal temperature

Higher exhaust emissions


Poor fuel mileage


A high-quality OEM thermostat should be used. Poor quality thermostats may not function properly and can cause damage to the engine orcomponents of the emission system.

We recommend replacing the thermostat any time major repairs are performed on the cooling system


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Thermostat Gasket

The thermostat gasket is a working seal between the thermostat housing and the engine.


Thermostat housing may leak coolant

Engine may overheat


We recommend replacing the thermostat any time major repairs are performed on the cooling system


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Throttle Body

The throttle body is a housing containing a valve(s) that regulates the airflow entering the intake manifold on its way to the combustion chamber. The

valve(s) opens and closes based on driver input via the gas pedal.


Stalling problems

Engine may run roughly

Illumination of the Check Engine Light

Gas pedal hard to push as a result of a worn throttle shaft


Residue build up on the throttle bore can result in lower than normal engine idle and engine stalling, especially after battery replacement

Newer vehicles are using an electronically-controlled throttle body in place of the older cable-operated system

When replacing an electronic throttle body, the related connectors and wiring should be thoroughly inspected


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Timing Belt

The rubber timing belt connects the camshaft to the crankshaft of the engine. It helps the crankshaft drive the camshaft.


Broken belt

Engine will stop running and internal engine damage can occur

Worn or loose belt

Belt may "jump time" (skipping a tooth or more, usually on the cam gear). This results in a loss of synchronization and engine performance.

Trouble codes from the camshaft or crankshaft sensors, causing Check Engine Light to illuminate

Slapping or scraping noises from engine


It is crucial that the timing belt be replaced at or before the interval recommended by the vehicle manufacturer. Failure to do so can result in a brokentiming belt, which can turn off your engine and leave you stranded. It could also lead to severe engine damage.

Timing belts are used in lieu of timing chains in many engines. Since they are made out of rubber, they have a limited lifespan.

It is often recommended that you replace items like the water pump, front engine seals, drive belts, idlers, and tensioner along with the timing belt


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Timing Chain

The metal timing chain connects the camshaft to the crankshaft of the engine. It helps the crankshaft drive the camshaft.


Engine may stall or run rough

Noise in the front of the engine (a rattle or rumble, associated with engine speed)

Check Engine Light may illuminate and set misfire, camshaft sensor, and crankshaft sensor codes


On certain engines, the water pump is driven by the timing chain. It should be replaced if the timing chain is replaced.

When replacing a timing chain, replace the whole timing chain set, which includes all of the chains, the gear set, the tensioner(s), and the guides

An engine may have multiple timing chains; replacing all of the chains and their related components is recommend if one chain requires replacement

Using high quality, fully synthetic engine oil may extend the life of the timing chain and related components

Sometimes, a defective water pump, a loose or defective harmonic balancer, a defective drive belt tensioner, or a cracked flex plate can exhibitsymptoms that may be misdiagnosed as a worn timing chain assembly


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Timing Cover

A timing cover is a metal or plastic enclosure that covers and protects the timing components from dirt, dust, and debris.


Engine oil and/or coolant leak

Scraping or rattle noise from front of engine

Missing timing mark


When replacing the timing belt or chain, the timing cover should be inspected for damage and replaced, if necessary

If the timing cover is removed to correct a leak, the timing components should be thoroughly inspected and replaced, if necessary


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Timing Cover Gasket

The timing cover gasket is the working seal between the timing cover and the engine block.


Oil or coolant leak


The timing cover gasket may be made from standard gasket material, an O-ring style seal, or it may be sealed with a simple silicone-type sealant

If the timing cover is removed to correct a leak, the timing components should be thoroughly inspected and replaced, if necessary


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Vacuum Pump

The vacuum pump produces the vacuum power needed for vehicle functions such as braking and some HVAC functions.


Brake pedal may be hard

Heating, ventilation, and AC (HVAC) system may malfunction

Abnormal noise


It's a good idea to use a factory quality (OEM) vacuum pump. If the pump is belt driven, replace the drive belt as well.

Components that rely on the vacuum pump (climate control and/or brake system components) may be incorrectly replaced if there is an issue with thevacuum pump

Vacuum pumps are used on Diesel engines (since they do not produce vacuum) and on some gasoline engines that produce little vacuum, such asturbos


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Valve Cover

A valve cover is a metal or plastic covering that protects the valve train and camshaft(s) in each cylinder head. It keeps oil from leaking out into the

engine compartment and debris from getting into the cylinder head.


Engine oil leak

Burning smell due to oil on exhaust manifold


Many new vehicles use plastic valve covers. These can crack and cause an oil leak.

A leaking valve cover or gasket can drip oil all over the engine. In some cases, it's necessary to repair the valve cover leak before any other oil leakscan be properly diagnosed.


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Valve Cover Gasket Set

The valve cover gasket set is the complete set of gaskets required to create the working seal between the valve cover(s) and the cylinder head(s).


Engine oil may leak

Burning smell due to oil on the exhaust manifold

Engine misfire


Valve cover gaskets and seals need to be replaced when they begin to leak oil. This type of leak can damage other engine components, especiallybelts, hoses, and spark plug wires.

Using high-quality valve cover gaskets will reduce the chance of recurring leaks and additional repairs

An engine misfire can result from oil leaking into the spark plug tubes. The tube seals and valve cover gasket should always be replaced together.

When replacing the valve cover gasket, we recommend having a valve adjustment performed, if applicable. Since the valve cover is removed toadjust the valves, this will save in labor costs.


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Water Pump

The water pump, also known as the coolant pump, circulates coolant through the engines cooling system.


Noise from engine area, including a rumbling sound

Coolant leak

Engine overheating


When replacing the water pump, the drive belts may need to be removed. The belts should be replaced if they show signs of wear.

The water pump may be driven by the timing belt or chain. It these cases, it is common to replace the water pump when the belt or chain is replaced.

Water pumps require replacement if they begin to leak coolant or become noisy. A leaking water pump can result in damage to the drive and timingbelts.

A failed water pump can be caused by problems in the cooling system, such as a failing thermostat, radiator, or head gasket

The entire cooling systemincluding all of the coolant hoses and fittings, radiator, coolant fan(s), and fan clutch (if equipped)should be inspectedwhen replacing the water pump



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Most water pumps are either driven independently via

their own belts or are driven by a serpentine belt that also drives many other components. Some current designs use the timing belt to drive the water

pump. In these cases, it is advisable to replace the water pump in conjunction with scheduled timing belt replacement.


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Water Pump Gasket

The water pump gasket is the working seal between the water pump and the engine.


Coolant leak

Engine overheating


If the water pump gasket is leaking, the water pump should be replaced along with the leaking gasket

When replacing the water pump or gasket, the drive belts may need to be removed. The belts should be replaced if they show signs of wear.

The entire cooling systemincluding all of the coolant hoses and fittings, radiator, coolant fan(s), and fan clutch (if equipped)should be inspectedwhen replacing the water pump or gasket


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