How Do You Tell If a Car's Thermostat Is Clogged?

When the thermostat of a vehicle is stuck closed the car will overheat and the heating system will not function. A stuck thermostat can lead to more serious problems, such as a blown head gasket, if not quickly maintained.

The thermostat is mounted on the engine before the top radiator hose. Its primary function is to cool the engine off after a predetermined temperature is reached. This allows the engine to cool off quickly and effectively. There are numerous symptoms of a clogged thermostat.

  • Overheating - when the thermostat is stuck close coolant will no longer be able to flow directly into the engine and it will quickly overheat
  • Radiator making noise - the radiator will begin making a noise similar to the knocking of a steam pipe
  • Heater will not work - the heater core is found behind the engine. The purpose of the heater core is to use the heat of the coolant pipes to warm up the air. When the thermostat is closed there will not be any coolant flowing through the heater core, which will cause the heating system in the car to blow cool air as opposed to hot

Once the thermostat fails, it needs to be replaced. To replace it, simply flush the coolant from the system, locate the housing and remove the old thermostat. Install the new thermostat and refill the coolant.