Cooling System Parts

Selecting the right Coolant

There are three main types of coolant:

Inorganic Additive Technology (IAT)
Organic Additive Technology (OAT)
Hybrid Organic Acid Technology (HOAT)

Generally older cars use IAT.

GMC/Chevy uses Dexcool

Ford uses Motocraft

HOWEVER, in order to determine what antifreeze you need, it is best to check with the manufacturer of the vehicle.

Dealerships will sell their recommended brand at their dealership. The additives that are in these coolants are helpful to keep the seals from degrating, so mixing two types of antifreeze should NEVER be done!

Water Pump

The water pump pulls antifreeze/coolant from the radiator and pushes it into the engine block IF the thermostat is open!

Thermostat

The thermostat controls coolant movement out of the block and into the radiator

Radiator

The radiator's purpose is to allow air outside of the car to absorb the heat transferred from the engine block via the coolant.

Radiator Hoses & Heater Core

Radiator hoses are flexible connections between the engine and radiator and the heater core.

The reason the heat in your vehicle cabin is not hot immediately afterr starting is because the excess heat from the engine FIRST must heat up the coolant (antifreeze). This is then circulated through the heater core where a fan pushes air past the fins to warm up the air that contacts the heater core.

Coolant Temperature Sensor (CTS)

Also called an Engine Coolant Temperature Sensor (ECTS)

To get an accurate reading of the current engine temperature, the ECU sends a regulated voltage to the CTS.

The resistance of the sensor varies with temperature, this is how the ECU can monitor temperature changes.

The ECU uses this reading to calculate the coolant temperature, and from there adjusts the fuel injection, fuel mix, and ignition timing, and controls when the electric cooling fan is switched on and off. This information is also used to send an accurate reading of the engine temperature to a gauge on the dashboard.

Freeze Plugs

These steel plugs were designed to seal holes in the engine block and cylinder head(s) created during the casting process. In freezing weather they may push out if there is not enough anti-freeze protection.

Head Gasket & Timing Cover Gasket

This pair seal the major parts of the engine.

They prevents oil, anti-freeze and cylinder pressure from mixing together.

Fan Clutch

Senses the temperature of the air coming through the radiator and either slips or binds up to pull the required amount of air through the radiator.

The fan clutch system is seldomly used as most manufacturers have moved to a sensor connected to the ECM to turn an electric fan on (as seen on right).

Electric Cooling Fan

Most front wheel drive cars use this because of the transverse mounted engine. It is turned on by a system of sensors and relays when the engine reaches about 230 F and stays on until R is cooled to about 200 F.

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