The thermostat in a Toyota regulates the amount of radiator fluid allowed to flow through the engine. Depending on the needs of the vehicle, the thermostat will allow or restrict the fluid. The thermostat is a mechanical part in the engine and not an electronic module. This means the thermostat can break or wear out. When this happens, the thermostat must be replaced. This may sound like a job for a mechanic, but it is absolutely possible to avoid the repair shop by completing the job yourself.
Trace the top radiator hose to the intake manifold to locate the thermostat. The radiator hose is a band clamped to the housing that holds the thermostat. The location will differ, depending on the model of Toyota and the engine size you are repairing.
Disconnect the radiator hose from the thermostat housing by removing the band clamp that's around the radiator hose. Use a Phillips screwdriver. Once the band clamp is loosened, pull the hose off the thermostat housing.
Remove the two bolts that hold the thermostat housing to the intake manifold. Most thermostats are on the back of the engine and can be hard to get to with a wrench. Using a 12mm socket with an extender (often called a breaker bar) will make it easier to reach the bolts. Once the bolts are removed, lift the thermostat housing off the intake manifold.
Lift the thermostat out of the manifold. It is not bolted into place. Place a towel into the hole to block debris from getting inside the engine. Use a scraper and scrape the old thermostat housing gasket off the intake manifold. Clean all debris off the manifold and remove the towel.
Place the new thermostat into the intake manifold and place a new thermostat housing gasket in place. Bolt the housing back onto the manifold. Make sure the thermostat is placed back into the intake with the correct side up. This will ensure the thermostat works properly.
