The engine cooling system uses a coolant solution of ethylene glycol (DEX-COOL™) and water. The solution carries excess heat away from the engine block and the air compressor. A belt driven water pump moves the coolant solution through the engine cooling system. The heated coolant flows through the radiator. In the radiator, the heat is transferred to the outside air. The cooled fluid then flows back to the engine block.

The coolant dissipates heat as it passes through the radiator tubes and through the radiator. Radiators transfer heat from the coolant to the outside air that is pulled past the radiator fins and the tubes by the engine cooling fan.

The fan draws the air through the radiator fins in order to cool the radiator and the coolant. Air flow is directed by a fan shroud. The shroud prevents the air from recirculating around the radiator. A missing or damaged shroud can cause overheating.

The thermostatic fan clutch is driven directly from the engine crankshaft and controls the torque that is transmitted from the engine crankshaft to the fan blades. The fan clutch allows more torque to engage on the fan under the following conditions:

With more torque, the fan turns faster and draws more air into the radiator. The thermostatic fan clutch disengages under the following conditions:

The engine operating temperature is regulated by the thermostat. The thermostat is located in the coolant outlet at the front of the engine. The thermostat opens and allows coolant to flow to the radiator when the engine reaches a predetermined temperature. The thermostat closes in order to restrict coolant flow as the engine cools down. The thermostat also controls the amount of coolant that is flowing through the engine.

The cooling system operates under pressure in order to increase the efficiency of the cooling system. Operating the system under pressure does the following:

The pressure cap on the surge tank regulates the cooling system pressure. The pressure cap is designed with two normally-closed valves. The pressure relief valve opens when the coolant temperature and the pressure exceed the pressure valve spring tension. The pressure relief valve allows coolant or air to escape. The pressure relief valve is set for 62 kPa (9 psi). The vacuum valve opens when the coolant is cooling and when ambient pressure exceeds the vacuum valve spring tension. The vacuum valve allows coolant in the recovery reservoir or in the surge tank to re-enter the system. The vacuum valve also prevents the collapse of the hoses and other engine components that are not internally supported.

A 50/50 combination of water and ethylene glycol (DEX-COOL™) antifreeze coolant that meets GM 6277M specifications is recommended for year-round use. The coolant solutions that you use must provide the following: