Thermostat: Service and Repair

Engine Coolant Thermostat Replacement (4.2L Engine)

Special Tools

J 38185 Hose Clamp Pliers

Removal Procedure

1. Remove the necessary coolant from the radiator. Refer to Cooling System Draining and Filling (LH6) (Cooling System Draining and Filling)Cooling System Draining and Filling (LL8) (Cooling System Draining and Filling).
2. Remove the generator. Refer to Generator Replacement (With 4.2L Engine) (Generator Replacement)Generator Replacement (5.3L Engine) (Generator Replacement).




3. Loosen the outlet hose clamp at the thermostat housing (1). Remove the outlet hose from the thermostat housing.




4. Remove the thermostat housing bolts.
5. Remove the thermostat housing from the engine block.
6. Clean all of the surfaces of the thermostat housing.
7. Clean the sealing surface of the engine block.

Installation Procedure




1. Install the thermostat housing to the engine block.

Caution: Refer to Fastener Caution (Fastener Caution).

2. Install the thermostat housing bolts and tighten to 10 Nm (89 in. lbs.).
3. Lubricate the inner diameter of the radiator hose with engine coolant.




4. Install the outlet hose to the thermostat housing (1). Secure the hose with the clamp.
5. Install the generator. Refer to Generator Replacement (With 4.2L Engine) (Generator Replacement)Generator Replacement (5.3L Engine) (Generator Replacement).
6. Fill the cooling system with specified coolant and concentration. Refer to Cooling System Draining and Filling (LH6) (Cooling System Draining and Filling)Cooling System Draining and Filling (LL8) (Cooling System Draining and Filling).
7. Inspect all sealing surfaces for leaks after starting the engine.