Thermostat: Description and Operation

DESCRIPTION
The water thermostat ensures rapid engine warm-up by restricting engine coolant flow at lower operating temperatures. It also assists in keeping the engine operating temperature within predetermined limits.
^ When the coolant is cold, the water thermostat (8575) is in the closed position and the coolant flow is restricted to the cylinder block (6010), cylinder heads (6049), intake manifold (9424) and heater core.
^ As the temperature increases, the water thermostat opens, allowing a portion of the coolant to pass into the radiator (8005).