For 1990-2009 cars

#### Engine Coolant Thermostat

The engine coolant thermostat is located on the top of the water pump housing and is covered by a water outlet. The thermostat regulates the coolant flow from the radiator to the water pump. A pellet-type engine coolant thermostat is used in the engine coolant inlet passage in order to control the flow of engine coolant, to provide fast engine warm-up and to regulate engine temperatures. A wax pellet element in the thermostat expands when heated and contracts when cooled. A piston connects the pellet element to a valve. The valve remains closed while the engine coolant is cold, allowing full circulation of engine coolant through the engine, throttle body heater and heater core and prevents circulation of engine coolant through the radiator. As the engine warms, the pellet element expands and the thermostat valve opens. This permits full engine coolant flow throughout all components of the cooling system.