Thermostat: Service and Repair

Engine Coolant Thermostat Replacement

Removal Procedure

1. Drain the cooling system. Refer to Cooling System Draining and Filling (Service and Repair).
2. Remove the generator. Refer to Generator Replacement (Generator Replacement).




3. Remove the following components from the cylinder block:

* The 2 nuts (1)
* The thermostat housing

4. Remove the following components from the thermostat housing:

* The thermostat
* The O-ring

5. Clean the following materials from the thermostat cap:

* Corrosion
* Debris

6. Clean the cylinder block mating surfaces.
7. Inspect the thermostat. Refer to Thermostat Diagnosis (Component Tests and General Diagnostics).



Installation Procedure






Important: Position the air bleed valve facing upward.


1. Install the thermostat.
2. Install a new thermostat O-ring.




3. Install the thermostat housing to the cylinder block.

Notice: Refer to Fastener Notice .

4. Use the 2 nuts (1) in order to secure the thermostat cap.

* On low output engine, tighten the thermostat cap nuts to 11 N.m (8 lb ft).
* On high output engine, tighten the thermostat cap nuts to 10 N.m (7 lb ft).


5. Install the generator. Refer to Generator Replacement (Generator Replacement).
6. Fill the radiator using approved coolant. Refer to Cooling System Draining and Filling (Service and Repair).
7. Start the engine.
8. Run the engine until the coolant is at operating temperature. The coolant is at operating temperature when the following conditions exist:

* The hoses feel warm.
* The coolant is flowing through the radiator.

9. Inspect for leaks in the cooling system.
10. Turn off the engine.
11. Install the radiator cap.