Auto Repair Encyclopedia
Thermostat Replacement
Sometimes referred to as Thermostat, Replace Thermostat, Thermostat Replace
The thermostat is a valve that keeps coolant circulating in the engine until it reaches normal running temperature. When this happens, the thermostat opens and allows coolant to flow to the radiator. If the thermostat fails to open, the engine will overheat. If the thermostat sticks open, the engine will take longer than normal to reach operating temperature, causing poor heater performance, higher exhaust emissions, and on some vehicles, the check engine light to illuminate.
To replace the thermostat, the cooling system is drained, the radiator hose is removed from the thermostat housing, and the housing is removed from the engine. The thermostat and its housing gasket are replaced, the housing and hose are reassembled, and the cooling tank is filled with fresh coolant.
About this Repair: Thermostat Replacement
Recommendations
The entire cooling system should be inspected and tested when the thermostat is replaced.
A high-quality OEM thermostat should be used. Poor quality thermostats may not function properly and can cause damage to the engine or components of the emission system.
Why this happens
A thermostat that is stuck closed will cause the vehicle to overheat.
A thermostat that is stuck open can cause the engine to run colder than normal, set the check engine light, poor fuel mileage and a heater that blows cool air.
If the new thermostat does not immediately resolve engine temperature problems, the cooling system needs to be checked for other issues.
