The Cooling System

VocabularyVocabulary

1.1. Thermostat bypass 11.Hoses-clampsThermostat bypass 11.Hoses-clamps

2.2. Sending unit 12.Coolant-ethyleneSending unit 12.Coolant-ethylene

3.3. Fan clutch 13.CorrosionFan clutch 13.Corrosion

4.4. Heater core 14.Temperature gaugeHeater core 14.Temperature gauge

5.5. Water-cooled 15.Closed cooling systemWater-cooled 15.Closed cooling system

6.6. Air-cooled 16.Radiator capAir-cooled 16.Radiator cap

7.7. Water pump-impeller 17.ThermostatWater pump-impeller 17.Thermostat

8.8. ““V” belt/serpentine beltV” belt/serpentine belt

9.9. RadiatorRadiator

10.10. Radiator fan shroud Radiator fan shroud

At 2500 rpm & medium At 2500 rpm & medium load a 350 cid. V-8 load a 350 cid. V-8 engine produces enough engine produces enough cooling system heat in 15 cooling system heat in 15 minutes to heat three minutes to heat three 2000 square foot houses 2000 square foot houses in Chicago during in Chicago during January. January.

Purpose of cooling Purpose of cooling systemsystem The purpose of the cooling system is The purpose of the cooling system is

to do three things:to do three things:– To maintain the most efficient operating To maintain the most efficient operating

temperature within the engine.temperature within the engine.– To remove excess heat from the engine.To remove excess heat from the engine.– To bring the engine up to operating To bring the engine up to operating

temperature as quickly as possible.temperature as quickly as possible.

Wrong Eng. Temp.Wrong Eng. Temp.

If the engine temperature is too If the engine temperature is too highhigh Overheating of lubricating oil. This Overheating of lubricating oil. This

will result in the lubricating oil will result in the lubricating oil breaking down.breaking down.– Overheating of the parts. Cylinder wall, Overheating of the parts. Cylinder wall,

piston & bearing scuffing. Cylinder piston & bearing scuffing. Cylinder head warpage & head gasket failure.head warpage & head gasket failure.

– Engine temp should never exceed 230 Engine temp should never exceed 230 degrees F.degrees F.

Wrong Eng. Wrong Eng. TemperatureTemperature If the engine temperature is too If the engine temperature is too

lowlow, various problems will occur:, various problems will occur:– Poorer fuel mileage. Poorer fuel mileage. – Increases in carbon buildup. Increases in carbon buildup. – Increases in varnish and sludges Increases in varnish and sludges

within the lubrication system.within the lubrication system.– excessive exhaust emissions. excessive exhaust emissions. – excessive engine wear.excessive engine wear.

Heat TransferHeat Transfer

The cooling system The cooling system works on the principles works on the principles of heat transfer. Heat of heat transfer. Heat will always travel from a will always travel from a hotter to a cooler object.hotter to a cooler object.

Heat transfers in three Heat transfers in three ways: conduction, ways: conduction, convection, and convection, and radiation.radiation.

Conduction is defined as Conduction is defined as transfer of heat between transfer of heat between two solid objects.two solid objects.

In this picture, heat In this picture, heat must be transferred must be transferred from the valve guide.from the valve guide.

Types of Cooling Types of Cooling SystemSystem Engine manufacturers commonly use two Engine manufacturers commonly use two

types of cooling systems. These are the air-types of cooling systems. These are the air-cooled and liquid cooled systems.cooled and liquid cooled systems.

Air-cooled enginesAir-cooled engines– Air cooled engines have fins or ribs on the outer Air cooled engines have fins or ribs on the outer

surfaces of the cylinders and cylinder heads.surfaces of the cylinders and cylinder heads.– The fins increase the surface area of the object The fins increase the surface area of the object

which, in turn, increases the amount of convection which, in turn, increases the amount of convection and radiation available for heat transfer.and radiation available for heat transfer.

– The heat produced by combustion transfers from The heat produced by combustion transfers from the internal parts of the engine by conduction to the internal parts of the engine by conduction to the outer fins.the outer fins.

Types of Cooling Types of Cooling SystemsSystems Liquid-cooled EnginesLiquid-cooled Engines

– In the liquid-cooled engine, the heat from In the liquid-cooled engine, the heat from the cylinder is transferred to a liquid flowing the cylinder is transferred to a liquid flowing through jackets surrounding the cylinders.through jackets surrounding the cylinders.

– The liquid then passes through a radiator.The liquid then passes through a radiator.– Air passes through the radiator removes Air passes through the radiator removes

the heat from the liquid to the air.the heat from the liquid to the air.– Liquid cooling systems are designed to Liquid cooling systems are designed to

maintain a coolant temperature of 180-210 maintain a coolant temperature of 180-210 degrees F.degrees F.

Types of Cooling Types of Cooling SystemsSystems Liquid-coolant FlowLiquid-coolant Flow

– When the vehicle is started the coolant When the vehicle is started the coolant pump begins circulating the coolant.pump begins circulating the coolant.

– The coolant goes through the cylinder The coolant goes through the cylinder block from the front to the rear.block from the front to the rear.

– The coolant circulates around the The coolant circulates around the cylinders as it passes through the cylinders as it passes through the cylinder block.cylinder block.

Types of Cooling Types of Cooling SystemsSystems

– The coolant then passes up into the The coolant then passes up into the cylinder head through the holes in the cylinder head through the holes in the head gasket.head gasket.

– It then moves forward to the front of the It then moves forward to the front of the cylinder head through internal passages. cylinder head through internal passages. These passages permit cooling of high-These passages permit cooling of high-heat areas such as the spark plug and heat areas such as the spark plug and exhaust valve areas.exhaust valve areas.

– As the coolant leaves the cylinder head, it As the coolant leaves the cylinder head, it passes through a thermostat on the way to passes through a thermostat on the way to the radiator. the radiator.

Water JacketsWater Jackets

Open spaces within Open spaces within the cylinder block the cylinder block and cylinder head and cylinder head where coolant flows.where coolant flows.

Water jackets are Water jackets are designed to allow designed to allow coolant flow to the coolant flow to the right spots so that right spots so that maximum cooling maximum cooling can be obtained.can be obtained.

Water PumpWater Pump

The purpose of the water pump is to The purpose of the water pump is to circulate the water through the cooling circulate the water through the cooling system.system.

The pump is located on the front of the The pump is located on the front of the engine.engine.

In most vehicles it is driven by a belt In most vehicles it is driven by a belt that is attached to the crankshaft.that is attached to the crankshaft.

As the crankshaft turns the fan belt As the crankshaft turns the fan belt turns the pump, causing coolant to be turns the pump, causing coolant to be circulated. circulated.

Water PumpWater Pump

The pump consist of a housing, a bearing The pump consist of a housing, a bearing on a shaft, the impeller, and seal.on a shaft, the impeller, and seal.

The housing has a coolant inlet and The housing has a coolant inlet and outlet. The seal is used to keep the outlet. The seal is used to keep the water inside the pump. The bearing is water inside the pump. The bearing is used to support the shaft on which the used to support the shaft on which the impeller rides.impeller rides.

The Impeller causes the water to The Impeller causes the water to circulate.circulate.

ThermostatThermostat

One of the most important parts of the One of the most important parts of the cooling systems.cooling systems.

The purpose of the thermostat is to The purpose of the thermostat is to keep the engine coolant at most keep the engine coolant at most efficient temperature.efficient temperature.

The thermostat is used to bring the The thermostat is used to bring the coolant temperature up to operating coolant temperature up to operating as quickly as possible.as quickly as possible.

It is designed to sense the It is designed to sense the temperature of the coolant.temperature of the coolant.

ThermostatThermostat

A A wax pelletwax pellet material within the material within the thermostat expands thermostat expands and causes the and causes the mechanical motion mechanical motion that opens the that opens the thermostat.thermostat.

This allows the This allows the coolant to pass coolant to pass through the through the radiator.radiator.

Thermostat Thermostat

The thermostat is The thermostat is usually placed usually placed near the front of near the front of the engine.the engine.

This picture shows This picture shows how the how the thermostat is thermostat is placed with the placed with the thermostat thermostat housing cover.housing cover.

Radiator Radiator

The purpose of the radiator is to allow fresh The purpose of the radiator is to allow fresh air to reduce the temperature of the coolant.air to reduce the temperature of the coolant.

This is done by flowing the coolant through This is done by flowing the coolant through tubes. As the coolant passes through the tubes. As the coolant passes through the tubes air is forced around the tubes.tubes air is forced around the tubes.

This causes a transfer of heat from the hot This causes a transfer of heat from the hot coolant to the cooler air. This is called heat coolant to the cooler air. This is called heat exchanged.exchanged.

In this case, heat is exchanged from a liquid, In this case, heat is exchanged from a liquid, the coolant, to air. this is called a liquid-to air the coolant, to air. this is called a liquid-to air heat exchanger.heat exchanger.

Modern radiator Fan Shroud

RadiatorRadiator

This picture shows This picture shows an internal diagram an internal diagram of a typical radiator of a typical radiator core.core.

Coolant flows Coolant flows through the tubes, through the tubes, and air flows and air flows through the air fins.through the air fins.

Radiators are made Radiators are made of several parts. The of several parts. The fins and tubes are fins and tubes are called the core.called the core.

RadiatorRadiator

The core and fins on the radiator are made of The core and fins on the radiator are made of brass, copper, or aluminum or some brass, copper, or aluminum or some combination of those metals.combination of those metals.

There are also inlet and outlet tank. These There are also inlet and outlet tank. These tanks hold the coolant before it goes into the tanks hold the coolant before it goes into the radiator core or back into the block.radiator core or back into the block.

The inlet tank has a hose connection to allow The inlet tank has a hose connection to allow coolant to flow from the engine to the radiator.coolant to flow from the engine to the radiator.

The outlet tank has a hose connection to allow The outlet tank has a hose connection to allow coolant to pass back to the engine.coolant to pass back to the engine.

Radiator hosesRadiator hoses

Radiator hoses transport coolant from engine to radiator & back

cooling sys - Part 2 cooling sys - Part 2

Radiator Pressure CapRadiator Pressure Cap

Pressure caps are designed to:Pressure caps are designed to:– Increase the pressure on the cooling systemIncrease the pressure on the cooling system– Reduce cavitation Reduce cavitation – Prevent or reduce surgingPrevent or reduce surging

It is important to put pressure on the It is important to put pressure on the cooling system. cooling system. Radiator pressure caps Radiator pressure caps are typically near 15 pounds per square are typically near 15 pounds per square inch.inch.

As pressure increases the boiling point As pressure increases the boiling point of the coolant also increases. of the coolant also increases. ( about 3( about 3 degrees for each 1 psi increase)degrees for each 1 psi increase)

Pressure CapPressure Cap

During operation a During operation a spring holds desired spring holds desired pressure inside the pressure inside the cooling system, the cooling system, the vacuum valve is vacuum valve is pulled down and pulled down and opened as system opened as system cools.cools.

spring

Expansion TankExpansion Tank(closed system)(closed system) Cooling systems with Cooling systems with

expansion tanks are expansion tanks are also called closed also called closed cooling system.cooling system.

They are designed to They are designed to hold any coolant that hold any coolant that passes through the passes through the pressure cap when pressure cap when the engine is hot.the engine is hot.

This picture shows a This picture shows a expansion tank. expansion tank.

FanFan

The fan draws air The fan draws air through the radiator through the radiator for cooling during for cooling during low vehicle speed low vehicle speed and idle operation.and idle operation.

It is not needed at It is not needed at faster vehicle speed faster vehicle speed because air is because air is pushed through the pushed through the radiator by the radiator by the vehicle movement.vehicle movement.

The fan can absorb The fan can absorb up to 6% of the up to 6% of the engine horsepower.engine horsepower.

Clutch fan slips at higher engine speeds

Electric Fan Relay Electric Fan Relay

In order for the fan motor to start, In order for the fan motor to start, the engine cooling fan relay must the engine cooling fan relay must operate to close the switch. When operate to close the switch. When this is closed the fan switch will turn this is closed the fan switch will turn on.on.

The engine coolant temperature The engine coolant temperature switch closes because the engine switch closes because the engine temperature increased to a certain temperature increased to a certain point.point.

Coolant Temp. Coolant Temp. IndicatorsIndicators As the temperature of As the temperature of

the coolant increases the coolant increases to a certain level, the to a certain level, the heat from the engine heat from the engine causes an electrical causes an electrical circuit to close inside circuit to close inside the switch.the switch.

This switch connects This switch connects a warning light on the a warning light on the dashboard to ground dashboard to ground – completing a circuit – completing a circuit from the battery & from the battery & lighting the light.. lighting the light..

Coolant Temp. Coolant Temp. IndicatorsIndicators A second type of A second type of

temperature temperature indicator reads the indicator reads the actual coolant actual coolant temperature and temperature and displays this on the displays this on the dashboard of the dashboard of the vehicle.vehicle.

Fan BeltsFan Belts

Fan belt is used to turn the water Fan belt is used to turn the water pump and the fan. Using the V-type pump and the fan. Using the V-type belt produces a large area of belt produces a large area of contact.contact.

The flat serpentine belt is about 1 The flat serpentine belt is about 1 inch wide and has several grooves inch wide and has several grooves on one side and is flat on the other. on one side and is flat on the other. One Serpentine belt is often used to One Serpentine belt is often used to run all the engine accessories.run all the engine accessories.

Serpentine beltSerpentine belt

Belt routing Diagram

Serpentine belt routing

Types of coolantTypes of coolant

GreenGreen “older cars” “older cars” OrangeOrange “Dex cool - GM” “Dex cool - GM” Yellow Yellow “ford” “ford” Always check manufactures Always check manufactures

recommendations .recommendations . Coolants of different types should Coolants of different types should

never be mixed!!! never be mixed!!!

50 – 50 mix of Dex-50 – 50 mix of Dex-CoolCool

Pre mixing coolant & water

CoolantCoolant

Prevents Prevents FreezingFreezing

Increases boiling Increases boiling pointpoint

Lubricates water Lubricates water pumppump

Stops corrosionStops corrosion

Coolant Coolant

Hazardous WasteHazardous Waste– Antifreeze is considered hazardous waste Antifreeze is considered hazardous waste

product. It is harmful to people and to the product. It is harmful to people and to the environment.environment.

– the procedures and laws for disposing of the procedures and laws for disposing of antifreeze vary from state to state.antifreeze vary from state to state.

– The best method to dispose of antifreeze is The best method to dispose of antifreeze is to recycle the product. to recycle the product. Depending on the Depending on the city and region, there are various private city and region, there are various private and public organizations that collect and and public organizations that collect and recycle antifreeze.recycle antifreeze.

Coolant Coolant

Freezing PointsFreezing Points– when 100% water is used, the freezing when 100% water is used, the freezing

point is 32 degrees F. when 25% point is 32 degrees F. when 25% antifreeze and 75% water are used, the antifreeze and 75% water are used, the freezing point of the coolant is about freezing point of the coolant is about

-10 degrees F.-10 degrees F.

A 50% water 50% anti freeze mix will A 50% water 50% anti freeze mix will protect to around -50 degrees F.protect to around -50 degrees F.

This is all the protection needed in most This is all the protection needed in most areas of the united states.areas of the united states.

Coolant Coolant

Boiling PointsBoiling Points– Boiling point of a fluid is the temperature Boiling point of a fluid is the temperature

at which the fluid becomes a vapor.at which the fluid becomes a vapor.– Any coolant that becomes a vapor has Any coolant that becomes a vapor has

very poor conduction and convection very poor conduction and convection properties. So it is necessary to protect it properties. So it is necessary to protect it from boiling.from boiling.

CoolantCoolant

Corrosion can be produced several ways:Corrosion can be produced several ways:– Direct attack means the water in the coolant Direct attack means the water in the coolant

is mixed with oxygen from the air. This is mixed with oxygen from the air. This process can produce rust particles, which process can produce rust particles, which can damage water pump seals and cause can damage water pump seals and cause increase leakage.increase leakage.

– Electromechanical attack is a result of using Electromechanical attack is a result of using different metals in an engine. In the different metals in an engine. In the presence of a coolant, different metals may presence of a coolant, different metals may set up an electrical current in the coolant. If set up an electrical current in the coolant. If this occurs, one metal may deteriorate and this occurs, one metal may deteriorate and deposit itself on the other metal. deposit itself on the other metal.

Cooling system Cooling system pressure checkpressure check

Safety precautionsSafety precautions

Remember that a hot cooling system is Remember that a hot cooling system is approx 210 degrees F or hotter. Touching approx 210 degrees F or hotter. Touching the coolant or spilling the coolant on your the coolant or spilling the coolant on your body may cause serious injury.body may cause serious injury.

When working with coolant, for example When working with coolant, for example when replacing the water pump or when replacing the water pump or thermostat, you may spill some coolant thermostat, you may spill some coolant on the floor. The antifreeze in the coolant on the floor. The antifreeze in the coolant causes it to be very slippery. Immediately causes it to be very slippery. Immediately wipe up any coolant that spills.wipe up any coolant that spills.

Safety precautionsSafety precautions

Always wear proper clothing and eye Always wear proper clothing and eye protection when using coolant additives to protection when using coolant additives to remove silicate and calcium deposits; they remove silicate and calcium deposits; they may be very corrosive.may be very corrosive.

When working on the fan, water pump, or When working on the fan, water pump, or belts, make sure the engine ignition belts, make sure the engine ignition system is off or the battery is system is off or the battery is disconnected or both.disconnected or both.

Whenever the vehicle is running always Whenever the vehicle is running always keep fingers, tools, and clothing away keep fingers, tools, and clothing away from the moving fan.from the moving fan.

Safety precautionsSafety precautions

When working on the water pump, fan, or When working on the water pump, fan, or belts, be careful not to scrape your belts, be careful not to scrape your knuckles against the radiator.knuckles against the radiator.

Never remove the pressure cap when the Never remove the pressure cap when the engine is hot. Removing the pressure cap engine is hot. Removing the pressure cap releases the pressure on the cooling releases the pressure on the cooling system. This reduces the boiling point of system. This reduces the boiling point of the coolant. The coolant will then boil the coolant. The coolant will then boil violently and burn or injure a persons’ violently and burn or injure a persons’ hands or face. hands or face.

Safety PrecautionsSafety Precautions

When using a chemical cooling system When using a chemical cooling system cleaner, be careful not to get the cleaner, be careful not to get the chemical in your eyes or on your skin.chemical in your eyes or on your skin.

Keep antifreeze away from children Keep antifreeze away from children and animals. Antifreeze has a sweet and animals. Antifreeze has a sweet taste, and, if consumed it could lead to taste, and, if consumed it could lead to death in as little as 24 hrs. if antifreeze death in as little as 24 hrs. if antifreeze is ingested, see a doctor immediately. is ingested, see a doctor immediately.

Service Service

Common specification: Common specification: – Belt tensionBelt tension

NewNew 165lbs.165lbs. UsedUsed 100lbs.100lbs.

– Cooling system capacityCooling system capacity Without air conditioner (A/C)Without air conditioner (A/C)15.3quarts15.3quarts With air conditionerWith air conditioner 15.9quarts15.9quarts

– Radiator cap relief pressureRadiator cap relief pressure 16lbs.16lbs.– Thermostat opening Thermostat opening temperaturetemperature 195195°F°F

R&R Water Pump R&R Water Pump

Make sure the engine is cool or at Make sure the engine is cool or at room temperature.room temperature.

Remove the radiator capRemove the radiator cap Drain the coolant from the radiator Drain the coolant from the radiator

and cylinder block.and cylinder block. Remove the belts by loosening the Remove the belts by loosening the

appropriate components on the belt.appropriate components on the belt. On some engines the radiator may On some engines the radiator may

have to be removed to get at the have to be removed to get at the water pump.water pump.

Remove the fan if its driven by the Remove the fan if its driven by the water pump.water pump.

Remove the bolts holding the water Remove the bolts holding the water pump to the engine cylinder blockpump to the engine cylinder block

Scrape the old gasket completely off Scrape the old gasket completely off the blockthe block

Replace the old gasket with a new Replace the old gasket with a new gasket.gasket.

Replace the water pump with a new or Replace the water pump with a new or rebuilt pump.rebuilt pump.

Reverse the previous procedure to complete Reverse the previous procedure to complete assembly.assembly.

Before installing the belt, check the inside Before installing the belt, check the inside surface for wear. Twist the belt slightly to see if surface for wear. Twist the belt slightly to see if there are any cracks on the inside surface.there are any cracks on the inside surface.

Always check the reinforcement springs inside Always check the reinforcement springs inside the lower radiator hose.the lower radiator hose.

If the lower hose is replaced, make sure the If the lower hose is replaced, make sure the spring is not deformed, missing, or out of spring is not deformed, missing, or out of position.position.

Check the front of the radiator. Keep the front Check the front of the radiator. Keep the front clean and free of dirt, bugs, and other debris.clean and free of dirt, bugs, and other debris.

After all the parts have been inspected and After all the parts have been inspected and replaced, add the coolant back into the replaced, add the coolant back into the cooling system. Extra antifreeze may have to cooling system. Extra antifreeze may have to be added.be added.

Check the fan belts.Check the fan belts.– Always check the fan belts for wear and correct Always check the fan belts for wear and correct

tension.tension.– Tension on the fan belt can be checked by using the Tension on the fan belt can be checked by using the

gauge.gauge. After all parts have been inspected and After all parts have been inspected and

reassembled run the engine and pressure test reassembled run the engine and pressure test for leaks again.for leaks again.

When finished remove the pressure tester When finished remove the pressure tester and replace the pressure cap. and replace the pressure cap.

Good luck on your unit Good luck on your unit test!test!