Engine Coolant Thermostat Replacement 4.2L

Special Tools

J 38185 Hose Clamp Pliers

1. Remove the necessary coolant from the radiator. Refer to Cooling System Draining and Filling.
2. Remove the generator. Refer to 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.

1. Install the thermostat housing to the engine block.

Caution: Refer to Fastener Caution in the Preface section.

2. Install the thermostat housing bolts and tighten to 10 N·m (89 lb in).
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.
6. Fill the cooling system with specified coolant and concentration. Refer to Cooling System Draining and Filling.
7. Inspect all sealing surfaces for leaks after starting the engine.

Engine Coolant Thermostat Replacement 5.3L

Note: The thermostat is not serviceable separately. The water pump inlet and thermostat must be replaced as an assembly.

1. Remove the radiator outlet hose. Refer to Radiator Outlet Hose Replacement.
2. Remove the water pump inlet bolts.
3. Remove the water pump inlet and thermostat from the water pump.

1. Install the thermostat and thermostat housing to the water pump.

Caution: Refer to Fastener Caution in the Preface section.

2. Install the thermostat housing bolts and tighten to 15 N·m (11 lb ft).
3. Install the radiator outlet hose. Refer to Radiator Outlet Hose Replacement.