Skylark L4-144 2.4L DOHC VIN T SFI (1997)
Thermostat: Description and Operation
OPERATION
The 2.4L engine uses a pellet type thermostat in the radiator outlet pasage to control the flow of coolant. The thermostat provides faster engine
warm up and regulates coolant temperatures. A wax pellet or power element in the thermostat expands when heated and contracts when cooled.
The valve is connected to the power element. When the wax expands, the piston pushes against the flange and opens the thermostat. As the pellet
cools, contraction allows a spring-to close the valve. Thus, the valve remains closed while the coolant is cold. This prevents coolant, circulation
through the radiator, but allows the coolant to circulate through the engine to warm it quickly end evenly. As the engine becomes warm, the pellet
expands and the thermostat valve opens. This lets coolant flow through the radiator, where heat is passed through the radiator walls. This opening
and closing of the thermostat valve allows enough coolant to enter the radiator to keep the engine within specified temperature limits. A 91°C
(195°F) thermostat is used on engines where the thermostat is located in the engine coolant outlet. On engines where they thermostat is located in
the engine coolant inlet a 82°C (180°F) thermostat is used. Using thermostats rated above these control temperatures is not recommended. Higher
temperature thermostats will not provide faster warm up, since their valves remain tightly, closed until the control temperature is reached, as does
a lower temperature thermostat. The thermostat must be installed with the pointed end facing toward the radiator. Incorrect installation of the
thermostat may cause the engine to overheat.
