Cooling System: Description and Operation

The cooling system consists of an engine cooling module, thermostat, coolant, and a water pump to circulate the coolant. The engine cooling module may consist of a radiator, electric fan and motor assembly, shroud, radiator pressure cap, coolant recovery system (CRS), hoses, and clamps.
- When Engine is cold: Thermostat is closed, cooling system has no flow through the radiator. The coolant bypass flows through the engine only.
- When Engine is warm: Thermostat is full open, coolant flows through the radiator and flows through the heater to water pump.

Figure 1 Cooling System Operation:

Its primary purpose is to maintain engine temperature in a range that will provide satisfactory engine performance and emission levels under all expected driving conditions. It also provides hot water (coolant) for heater operation. It does this by transferring heat from engine metal to coolant, moving this heated coolant to the radiator and heater core, and then transferring this heat to the ambient air.