Thermostat: Service and Repair

Removal Procedure

Caution: 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. Refer to Coolant; Service and Repair.
2. Loosen the hose clamp on the upper radiator hose at the thermostat housing.





3. Disconnect the upper radiator 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 cylinder head.





6. Remove the O-ring seal from the thermostat housing.
7. Remove the thermostat from the thermostat housing by pressing the thermostat mounting flange downward and then rotating the flange clockwise.
8. Inspect the valve seat for foreign matter that could prevent the valve from sealing properly.
9. Inspect the thermostat for proper operation. Refer to Thermostat; Testing and Inspection.
10. Clean the thermostat housing and the cylinder head mating surfaces.

Installation Procedure





1. Install the thermostat into the thermostat housing by pressing the thermostat mounting flange downward and then rotating the flange counterclockwise. Rotate the thermostat mounting flange until it is seated in the thermostat housing recesses.
2. Coat the sealing surface of a new O-ring seal with Lubriplate.
3. Install a new O-ring seal into the recess in the thermostat housing.
4. Install the thermostat housing to the cylinder head.





5. Secure the thermostat housing to the cylinder head with the mounting bolts.
Tighten the thermostat housing mounting bolts (2.OL DOHC) to 15 Nm (11 ft. lbs.).





6. Connect the upper radiator hose to the thermostat housing.
7. Secure the upper radiator hose to the thermostat housing with a hose clamp.
8. Refill the engine cooling system. Refer to Coolant; Service and Repair.