Thermostat: Description and Operation

LOCATION
The engine thermostat is located on the front of the engine (radiator side) in the thermostat housing/ engine outlet connector. The thermostat has an air bleed (vent) located in the flange and a O-ring for sealing incorporate on it. There is a relief in the thermostat housing/outlet connector for the O-ring.

DESIGN
The engine cooling thermostats are wax pellet driven, reverse poppet choke type. They are designed to provide the fastest warm up possible by preventing leakage through them and to guarantee a minimum engine operating temperature of 88 to 93°C (192 to 199°F). They also automatically reach wide open so they do not restrict flow to the radiator as temperature of the coolant rises in hot weather to around 104°C (220°F). Above this temperature the coolant temperature is controlled by the radiator, fan, and ambient temperature, not the thermostat.

PERFORMANCE
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 performance. It does this by transferring heat from engine metal and automatic transmission oil cooler (if equipped) to coolant, moving this heated coolant to the heater core and radiator, and then transferring this heat to the ambient air.