Radiators operate by passing a liquid coolant through the engine block, where it is heated, then through the radiator itself where it loses this heat to the atmosphere. This coolant is usually water-based, but may also be oil. It’s usual for the coolant flow to be pumped, also for a fan to blow air through the radiator.

Radiator Caps

A radiator cap is high pressure cap used in radiators to allow operation at high temperature. Higher pressure raises the boiling point of the coolant.


A temperature sensitive device used in the cooling system of an engine to control the flow of coolant between the cylinder block and radiator. It is set into the engine block and shuts off the circulation of water until the temperature of the water reaches the point at which the thermostat is set to open. Because automotive Internal combustion engines operate more efficiently when their temperature is maintained within narrow limits, the thermostat closes off the flow of coolant from the engine to the radiator until the engine has reached the desired operating temperature. Other thermostats are used in the electrical circuit of the vehicle heating system to control the amount of heat supplied to the passengers, in the manifold heat control system that preheats the air-fuel mixture going to the cylinders and in the automatic choke.

Water Pumps

A device that circulates the liquid through the cooling system by pumping it from the engine cooling jackets to the radiator. The pump is usually mounted at the front of the engine and is driven by a belt from a pulley on the front end of the crankshaft.