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How to Check your Thermostat in Under 5 Minutes

A bad thermostat can ruin your car’s engine, so knowing how to tell when it's faulty is important. Indications of a problem include:

  • Overheating engine
  • Erratic fluctuations in temperature
  • Engine under heating
  • Engine performance is poor

To physically check your thermostat, you can follow these steps:

  1. Remove the thermostat once the engine is cool.
  2. Visually inspect it to ensure it is closed. If open, replace it.
  3. Submerge it in a pot of boiling water for one minute.
  4. Remove it from the water and inspect again.

The valve should be open (center section separated from base). If it isn’t, your thermostat needs to be replaced. A vehicle service professional can diagnosis the engine cooling system through special diagnostic procedures without thermostat removal.