The system functions as follows: Cold coolant from the bottom of the radiator flows through a hose to the water pump and is pumped through the main channels of the engine cylinder block, as well as through the oil cooler (where is there). After cooling the engine cylinders, combustion chamber and valve seats, the coolant is supplied to the thermostat, which is initially closed. The coolant also passes through the heater and returns through the cylinder block to the water pump.
When the engine is cold, the coolant circulates only through the cylinder block, cylinder head, and heater. When the coolant reaches a certain temperature, the thermostat begins to open and coolant flows through the upper hose to the radiator. As the coolant begins to circulate, it is cooled by the air flow as the car moves. If necessary, the air flow is increased by the operation of the electric fan. Once the coolant reaches the base of the radiator, the coolant has cooled and the cycle repeats.
When the engine reaches normal operating temperature, the coolant expands and is forced into the expansion tank. As the engine cools, the cooling system is replenished from the expansion tank.
On cars with an automatic transmission, some of the coolant flows from the base of the radiator through a cooler mounted on the transmission. On cars with an oil cooler, the coolant also flows through it.
The electric radiator fan is controlled by a temperature sensor, which turns on the fan when the coolant temperature exceeds a certain level.
Caution! When opening the expansion tank cap on a hot engine, be careful, as escaping hot steam and coolant can cause severe burns. Avoid contact of coolant with clothing and paintwork. If this happens, rinse the surface with plenty of water.
If the cooling system becomes depressurized while the engine is hot, place a cloth over the filler cap on the expansion tank and slowly unscrew the cap to relieve pressure. When all pressure in the cooling system has been relieved, remove the filler cap.