Engine Coolant Thermostat Replacement LY7

1. Partially drain the cooling system. Refer to Cooling System Draining and Filling.
2. Remove the heater inlet and outlet pipes. Refer to Heater Inlet Pipe Replacement and Heater Outlet Pipe Replacement.
3. Remove the thermostat housing bolts (1).
4. Remove the housing.
5. Remove the thermostat (3) and discard the thermostat seal (4).

1. Install the thermostat (3) with a NEW thermostat seal (4).

Caution: Refer to Fastener Caution in the Preface section.

2. Install the thermostat housing bolts (1) and tighten to 10 N·m (89 lb in).
3. Install the heater inlet and outlet pipes. Refer to Heater Inlet Pipe Replacement and Heater Outlet Pipe Replacement.
4. Fill the cooling system. Refer to Cooling System Draining and Filling.

Engine Coolant Thermostat Replacement LNJ

1. Remove the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement.
2. Drain the coolant until the coolant level is below the thermostat. Refer to Cooling System Draining and Filling.
3. Remove the crossover exhaust pipe. Refer to Exhaust Crossover Pipe Replacement.
4. Remove the radiator hose from the thermostat housing. Refer to Radiator Inlet Hose Replacement.



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.

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 in the Preface section.

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