DOE Quality Parts | Thermostats
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DOE Thermostats Are Manufactured to Original Equipment Standard.

When quality and integrity matter most.

Inspecting and replacing your thermostat

If your engine is taking a longer period of time than usual to warm up, the thermostat could be stuck open.

How To Inspect Your Thermostat

Remove your thermostat and put it in a shallow pan of water.

Slowly heat the water and watch the spring and valve open as the water approachesĀ  boiling point. A thermostat that operates optimally will open gradually. If the thermostat has been removed from a cold engine and it is open, you need a replacement.

Important: allow the engine to cool down before handling components of the cooling system.

Before doing any work on your vehicle, be sure to consult your car manual and follow safety instructions.

How To Replace Your Thermostat


Always follow manufacturer’s maintenance and saftey procedures.

Make sure the car is parked on level ground.

Drain the cooling system.

Unscrew the thermostat housing and water hose.

If you decide just to replace the thermostat, drain the coolant to a level just below that of the thermostat housing.

In newer vehicles the thermostat is incorporated into the housing and the entire unit needs to be replaced.

If your coolant is new, filter it into a clean container for reuse.

Inspect the thermostat housing for any signs of old glue or corrosion. Clean the thermostat housing carefully.

Position the new thermostat, insert the new gasket and replace the housing.

Go for a short drive and check that the temperature gauge remains at the correct temperature.

Check for any coolant leaks.