Thermostat: Service and Repair

Thermostat Removal

WARNING: To prevent personal injury, do not remove the surge tank cap while the engine and the radiator are hot because the heat causes the system to remain under pressure. Scalding fluid and steam may be blown out under pressure.

1. Drain the coolant.
2. Loosen the hose clamp on the coolant hose at the thermostat housing.





3. Disconnect the coolant hose from the thermostat housing.
4. Remove the mounting bolts that hold the thermostat housing to the cylinder head.
5. Remove the thermostat housing from the head.
6. Remove the O-ring seal from the head.
7. Check the valve seat for foreign matter that could prevent the valve from seating properly.
8. Check the thermostat for proper operation.





9. Clean the thermostat housing and the cylinder head mating surfaces.

Thermostat Installation
1. Coat the sealing surface of a new 0-ring seal with Lubricate (R).
2. Install a new O-ring seal into the recess in the cylinder head.





3. Secure the thermostat housing to the cylinder head with the mounting bolts.
Tighten the thermostat housing mounting bolts to 10 Nm (89 inch lbs.).
4. Connect the coolant hose to the thermostat housing.
5. Secure the coolant hose to the thermostat housing with a hose clamp.





6. Refill the engine cooling system.