Like any mechanical device, over time, a thermostat can fail, if the thermostat is stuck closed coolant can not flow into the radiator which will result in engine overheating, if the thermostat is stuck open the engine will not reach operating temperature which will cause the heater to stop working and a check engine light to come on.
Typically replacement parts will cost between $18.00 and $40.00 on Amazon (US) and will require the cooling system to be drained and the removal of the thermostat housing. Labor time can be between .8 and 2.0 hours at a shop or dealer. If exact times or procedures are needed you can ask our experts to supply you with the information (free), or consult an online resource such as AllData DIY (pay) but this guide and video will be sufficient in most cases.
Precautions: Engine coolant is toxic and can be fatal to animals and children so use caution when handling. Do not open the cooling system when the engine is hot.
Remove the vehicle's under shielding to locate the radiator drain valve, loosen
the valve to begin draining the coolant, close the valve once complete, if a drain
plug is not found remove the lower radiator hose to drain the coolant.
Please watch this video of the job being done, then continue down the guide to glean additional helpful information.
Here is what it looks like when the thermostat is removed and the sealing gasket
or O ring exposed. Clean the area using a shop towel and remove all debris which
will enable the new gasket to seal completely.
On some thermostats there is an air bleed valve on the face of the thermostat
body. This allows air to escape from the block when refilling the cooling system
and must be located at the top of the thermostat. The plunger is the part that opens
to allow the coolant to flow.
Reinstall the radiator hose and you are all set,
refill the cooling system
and start the engine, while the engine is warming up check for coolant leaks.
Our certified technicians are ready to answer engine cooling system thermostat questions for free. We hope you saved money and learned from this guide. We are creating a full set of car repair guides. Please subscribe to our 2CarPros YouTube channel and check back often for new videos which are uploaded regularly.