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Coolant Flow

The water pump forces coolant to flow throughout the engine. If the belt is slipping or not working properly the water pump will not circulate the coolant as needed and the engine will overheat. Coolant travels in passageways called water jackets (coolant voids) in the engine. Coolant, cooled from the car moving or from the radiator fan drawing in air across the radiator, flows from the radiator through the lower radiator hose, to the water pump, to the numerous water jackets in the engine, and then to the thermostat. If the coolant has reached operating temperature, the thermostat will open and allow the coolant to pass through the upper radiator hose back to the radiator to be cooled again. If the coolant has not reached operating temperature it will recirculate through the engine until it heats up to the thermostat’s rating. Some coolant is also diverted from the engine through the heater core. Heat is transferred from the heater core to the passenger compartment when the inside heater blower is turned on.