Engine Coolant Thermostat Replacement 4.3L Engine

1. Remove the air inlet duct. Refer to Air Cleaner Assembly Replacement in Engine Controls-4.3L.
2. Drain the cooling system. Refer to Cooling System Draining and Filling .
3. Remove the inlet hose. Refer to Radiator Inlet Hose Replacement .



4. Remove the coolant outlet studs.



5. Remove the coolant outlet from the lower intake manifold.



6. Remove the thermostat.
7. Clean all the sealing surfaces of the coolant outlet.
8. Clean the sealing surface on the lower intake manifold.
9. Remove the o-ring seal from the thermostat and discard.

Important: In order to prevent leakage, thoroughly clean all the parts and the sealing surfaces.

1. Install the new o-ring seal to the thermostat.
2. Install the thermostat into the lower intake manifold.



3. Install a new gasket .
4. Install the coolant outlet on the lower intake manifold.




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.

5. Install the coolant outlet studs.

Tighten
Tighten the coolant outlet studs to 19 N·m (14 lb ft).

6. Install the radiator inlet hose. Refer to Radiator Inlet Hose Replacement .
7. Install the air inlet duct. Refer to Air Cleaner Assembly Replacement in Engine Controls-4.3L.
8. Fill the cooling system. Refer to Cooling System Draining and Filling .
9. Test the system for leaks. Refer to Cooling System Leak Testing .

Engine Coolant Thermostat Replacement 4.8L, 5.3L, 6.0L Engines

1. Remove the air inlet duct. Refer to Air Cleaner Assembly Replacement in Engine Controls-4.8L, 5.3L, 6.0L.
2. Drain the cooling system. Refer to Cooling System Draining and Filling .
3. Remove the radiator outlet hose. Refer to Radiator Outlet Hose Replacement .



4. Remove the bolts.



5. Remove the thermostat from the water pump housing.



6. The O-ring seal is integral to the thermostat housing

1. Install the thermostat to the water pump housing.




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.

2. Install the bolts.

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

3. Install the radiator outlet hose. Refer to Radiator Outlet Hose Replacement .
4. Fill the cooling system. Refer to Cooling System Draining and Filling .
5. Install the air inlet duct. Refer to Air Cleaner Assembly Replacement in Engine Controls-4.8L, 5.3L, 6.0L.
6. Test the system for leaks. Refer to Cooling System Leak Testing .