Thermostat: Service and Repair

Engine Coolant Thermostat Replacement (LNJ) (3.4L)

Removal Procedure

1. Remove the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement (Service and Repair).
2. Drain the coolant until the coolant level is below the thermostat. Refer to Cooling System Draining and Filling (LY7 GE 47716 Fill) (Service and Repair)Cooling System Draining and Filling (LNJ GE 47716 Fill) (Service and Repair)Cooling System Draining and Filling (LNJ Static Fill) (Service and Repair)Cooling System Draining and Filling (LY7 Static Fill) (Service and Repair).
3. Remove the crossover exhaust pipe. Refer to Exhaust Crossover Pipe Replacement (LNJ) (Service and Repair).
4. Remove the radiator hose from the thermostat housing. Refer to Radiator Inlet Hose Replacement (LY7) (Service and Repair)Radiator Inlet Hose Replacement (LNJ Chevrolet) (Service and Repair)Radiator Inlet Hose Replacement (LNJ Pontiac) (Service and Repair).




5. Remove the thermostat housing bolts (3) and clean any sealer from the bolt threads.
6. Remove the thermostat housing (1).
7. Remove the thermostat (2).
8. Clean the mating surfaces.

Installation Procedure




1. Install the thermostat (2).
2. Install the thermostat housing (1).
3. Install RTV sealer, GM P/N 12378478 (Canadian P/N 88900041) or the equivalent, to the thermostat housing bolt threads.

Caution: Refer to Fastener Caution (Fastener Caution).

4. Install the thermostat housing bolts (3) and tighten to 25 Nm (18 lb ft).
5. Install the radiator hose to the thermostat housing. Refer to Radiator Inlet Hose Replacement (LY7) (Service and Repair)Radiator Inlet Hose Replacement (LNJ Chevrolet) (Service and Repair)Radiator Inlet Hose Replacement (LNJ Pontiac) (Service and Repair).
6. Install the crossover exhaust pipe. Refer to Exhaust Crossover Pipe Replacement (LNJ) (Service and Repair).
7. Install the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement (Service and Repair).
8. Fill the cooling system. Refer to Cooling System Draining and Filling (LY7 GE 47716 Fill) (Service and Repair)Cooling System Draining and Filling (LNJ GE 47716 Fill) (Service and Repair)Cooling System Draining and Filling (LNJ Static Fill) (Service and Repair)Cooling System Draining and Filling (LY7 Static Fill) (Service and Repair).
9. Inspect the cooling system for leaks. Repair as necessary.