Thermostat Housing: Service and Repair

Engine Coolant Thermostat Housing Replacement (LE5 and LE9) (2.4L)

Removal Procedure




1. Drain the cooling system. Refer to Cooling System Draining and Filling (GE 47716 Fill) Cooling System Draining and Filling (GE 47716 Fill)Cooling System Draining and Filling (LY7, LZE, LZ4, LZ9) Cooling System Draining and Filling (GE 47716 Fill).

Note: A drain has been provided at the bottom of the water pump for engine block coolant drainage.

2. Remove the water pump drain plug and drain the coolant from the engine block at the water pump drain.
3. Lower the vehicle.




4. Disconnect the engine coolant temperature (ECT) sensor electrical connector (1).
5. Disconnect the heated oxygen sensor (HO2S) electrical connector clip from the bracket.




6. Remove the ECT sensor.
7. Remove the surge tank outlet hose from the thermostat housing.




8. Reposition the radiator outlet hose clamp at the thermostat housing.
9. Remove the radiator outlet hose from the thermostat housing.




10. Remove the exhaust heat shield bolts.
11. Remove the exhaust heat shield.




12. Reposition the heater inlet and outlet hose clamps at the thermostat housing pipes.
13. Disconnect the heater inlet (1) and outlet (2) hoses from the thermostat housing pipes.




14. Remove the thermostat housing bolts.

Note: Twist the water transfer pipe while pulling in order to remove it from the water pump.

15. Remove the thermostat housing from the vehicle.
16. Remove the water transfer pipe from the thermostat housing, if necessary.
17. Remove and discard the water transfer pipe O-ring seals, if necessary.




18. Remove the thermostat housing cover bolts and cover, if necessary.
19. Remove the thermostat, if necessary.
20. Remove and discard the thermostat housing O-ring seal, if necessary.
21. Remove all debris and thread sealant from the engine coolant temperature sensor and bolt holes if the housing is being re-used.

Installation Procedure




1. Install a NEW thermostat housing cover O-ring seal into the recess groove.
2. Install the thermostat, if necessary.

Caution: Refer to Fastener Caution Fastener Caution.

3. Install the thermostat housing cover bolts, if necessary.

Tighten the bolts to 10 Nm (89 lb in).

4. Install a NEW thermostat housing to engine O-ring seal onto the thermostat housing.
5. Load the thermostat housing assembly into position while the vehicle is lowered.





Note: The water feed pipe seals can be lightly lubricated with coolant to aid during installation.

6. Install NEW O-ring seals onto the water feed pipe.

Note: Lubricate the O-rings with coolant ONLY.

7. Install the water feed pipe into the thermostat housing aligning locator tab.
8. Align the water pipe to water pump.
9. Seat the water feed O-ring seal by pushing inward toward the water pump. Take care not to tear or damage the O-ring.
10. Position the thermostat housing against the engine.
11. Install the thermostat housing bolts.

Tighten the bolts to 10 Nm (89 lb in).




12. Connect the heater inlet (1) and outlet (2) hoses to the thermostat housing pipes.
13. Position the heater inlet and outlet hose clamps at the thermostat housing pipes.




14. Install the exhaust heat shield.
15. Install the exhaust heat shield bolts.

Tighten the bolts to 23 Nm (17 lb ft).




16. Install the radiator outlet hose to the thermostat housing.
17. Position the radiator outlet hose clamp at the thermostat housing.




18. Install the radiator outlet hose to the surge tank.
19. Position the radiator outlet hose clamp at the surge tank.




20. Apply sealant to the threads of the ECT sensor. Refer to Adhesives, Fluids, Lubricants, and Sealers Adhesives, Fluids, Lubricants, and Sealers.
21. Install the ECT sensor.

Tighten the sensor to 20 Nm (15 lb ft).




22. Connect the ECT sensor electrical connector (1).
23. Connect the HO2S electrical connector clip to the bracket.




24. Apply sealant GM P/N 12378521 (Canadian P/N 88901148) or equivalent to the water pump drain plug.
25. Install the water pump drain plug.

Tighten the drain plug to 20 Nm (15 lb ft).

Note: The vehicle must be level when filling the cooling system.

26. Verify the drain valves at the radiator and water pump are closed.
27. Fill the cooling system. Refer to Cooling System Draining and Filling (GE 47716 Fill) Cooling System Draining and Filling (GE 47716 Fill)Cooling System Draining and Filling (LY7, LZE, LZ4, LZ9) Cooling System Draining and Filling (GE 47716 Fill).
28. Verify the repair and inspect for any leaks.