Engine Coolant Thermostat Replacement LS4

Special Tools

J 38185 Hose Clamp Pliers

1. Remove the radiator air lower baffle and deflector. Refer to Radiator Air Lower Baffle and Deflector Replacement .
2. Reposition the radiator inlet hose. Refer to Radiator Inlet Hose Replacement .
3. Partially drain the cooling system. Refer to Cooling System Draining and Filling .
4. Use the J 38185 in order to reposition the hose clamp from the water outlet housing.
5. Remove the radiator inlet hose from the water outlet housing.



6. Remove the water outlet housing bolts (302).
7. Remove the water outlet housing (303) and O-ring seal (304).
8. Remove the thermostat (305).
9. Clean and inspect the water outlet housing O-ring seal mating surfaces.

Notice: DO NOT use cooling system seal tabs, or similar compounds, unless otherwise instructed. The use of cooling system seal tabs, or similar compounds, may restrict coolant flow through the passages of the cooling system or the engine components. Restricted coolant flow may cause engine overheating and/or damage to the cooling system or the engine components/assembly.

1. Install the thermostat (305).
2. Install the O-ring seal (304) and water outlet housing (303).

Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

3. Install the water outlet housing bolts (302).

Tighten
Tighten the bolts to 15 N·m (11 lb ft).




4. Install the radiator inlet hose to the water outlet housing.
5. Use the J 38185 in order to reposition and install the hose clamp to the water outlet housing.
6. Fill the cooling system. Refer to Cooling System Draining and Filling .
7. Install the radiator inlet hose. Refer to Radiator Inlet Hose Replacement .
8. Install the radiator air lower baffle and deflector. Refer to Radiator Air Lower Baffle and Deflector Replacement .

Engine Coolant Thermostat Replacement RPOs LZE, LZ4, LZG

1. Drain the cooling system. Refer to Cooling System Draining and Filling .
2. Remove the air cleaner outlet duct. Refer to Air Cleaner Outlet Duct Replacement or Air Cleaner Outlet Duct Replacement .
3. Reposition the radiator outlet hose clamp at the thermostat housing.
4. Remove the radiator outlet hose from the thermostat housing (3.5L shown, 3.9L similar).



5. Remove the thermostat housing bolt/stud.
6. Remove the thermostat housing and gasket.
7. Remove the thermostat.
8. Clean the gasket surfaces.

1. Install a NEW thermostat.
2. Position a NEW gasket and the thermostat housing to the engine block.

Notice: Refer to Fastener Notice in the Preface section.

3. Install the thermostat housing bolt/stud.

Tighten
Tighten the bolt/stud to 10 N·m (89 lb in).




4. Install the radiator outlet hose to the thermostat housing (3.5L shown, 3.9L similar).
5. Position the radiator outlet hose clamp at the thermostat housing.
6. Install the air cleaner outlet duct. Refer to Air Cleaner Outlet Duct Replacement or Air Cleaner Outlet Duct Replacement .
7. Fill the cooling system. Refer to Cooling System Draining and Filling .
8. Inspect the system for leaks.