GM Service Manual Online
For 1990-2009 cars only

Engine Coolant Thermostat Housing Replacement LX9

Removal Procedure


    Object Number: 181846  Size: SH
  1. Drain the cooling system. Refer to Cooling System Draining and Filling .
  2. Remove the air cleaner outlet duct. Refer to Air Cleaner Inlet Duct Replacement in Engine Controls - 3.5L.
  3. Disconnect the surge tank hose from the coolant outlet.
  4. Remove the thermostat housing to intake manifold bolts.
  5. Remove the thermostat housing outlet and thermostat.

Installation Procedure


    Object Number: 181846  Size: SH
  1. Install the thermostat and housing outlet.
  2. 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 thermostat housing bolts.
  4. Tighten
    Tighten the thermostat housing bolts to 25 N·m (18 lb ft).

  5. Install the air cleaner outlet duct. Refer to Air Cleaner Inlet Duct Replacement in Engine Controls - 3.5L.
  6. Fill the cooling system. Refer to Cooling System Draining and Filling .
  7. Inspect the system for leaks.

Engine Coolant Thermostat Housing Replacement L61

Tools Required

J 38185 Hose Clamp Pliers

Removal Procedure

    Notice: The thermostat will not function correctly once it is contacted by oil. If oil is found in the cooling system, it must be flushed and the thermostat's cartridge replaced.


    Object Number: 1212661  Size: SH
  1. Remove the coolant cap from the surge tank.
  2. Place a coolant container under the radiator drain valve at the right hand side of the radiator tank.
  3. Using a flat-bladed screwdriver, open the valve and drain the coolant.
  4. Raise the vehicle on a hoist.

  5. Object Number: 1212666  Size: SH

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

  6. Drain the coolant from the engine block at the water pump drain. After the coolant has drained, tighten the drain bolt.
  7. Lower the vehicle.

  8. Object Number: 931384  Size: SH
  9. Disconnect the radiator hose and clamp from the thermostat pipe assembly using the J 38185 , or equivalent.

  10. Object Number: 931368  Size: SH
  11. Disconnect the surge tank return hose and clamp from the thermostat housing pipe.
  12. Remove the attachment bolt from the thermostat bracket assembly to thermostat pipe assembly near the front of the engine.

  13. Object Number: 951386  Size: SH
  14. Remove the exhaust heat shield bolts.
  15. Remove the exhaust heat shield.
  16. Disconnect the electrical connector at the coolant temperature sensor.
  17. Disconnect the O2 sensor connector and clip from the bracket.

  18. Object Number: 931420  Size: SH
  19. Disconnect the heater inlet and outlet hoses and clamps at the thermostat housing pipes.

  20. Object Number: 951404  Size: SH
  21. Remove the thermostat housing bolts to the engine.
  22. Important: Twist the water transfer pipe while pulling to remove it from the water pump.

  23. Remove the water transfer pipe from the thermostat housing.
  24. Remove the thermostat housing assembly from the vehicle.

  25. Object Number: 951792  Size: SH
  26. Remove the water transfer pipe O-seals and discard.
  27. Remove the thermostat housing cover bolts and cover.
  28. Remove and discard the thermostat housing O-seal.
  29. Remove the thermostat cartridge and inner sleeve from the thermostat housing.
  30. Remove all debris and thread sealant from the engine coolant temperature sensor and bolt holes if the housing is being re-used.

Installation Procedure


    Object Number: 951651  Size: SH
  1. Install the thermostat cartridge into the thermostat housing while aligning the cartridge tangs up with the thermostat housing bolt holes. This will assure the inner sleeve can be completely installed.

  2. Object Number: 951659  Size: SH
  3. Align and insert the inner sleeve notch into the thermostat housing. If the inner sleeve notch is not properly positioned, the sleeve will not completely seat into the housing.

  4. Object Number: 951626  Size: SH
  5. Install a new thermostat housing cover seal into the recess groove.
  6. Notice: Refer to Fastener Notice in the Preface section.

  7. Install the thermostat housing cover bolts.
  8. Tighten
    Tighten the thermostat housing cover-to-thermostat housing bolts to 10 N·m (89 lb in).

  9. Install a new thermostat housing to engine seal onto the thermostat housing.
  10. Load the thermostat housing assembly into position while the vehicle is lowered.
  11. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.

  12. Object Number: 951611  Size: SH

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

  13. Install new O-seals onto the water feed pipe.
  14. Important: Lubricate the O-rings with coolant ONLY.

  15. Install the water feed pipe into the thermostat housing aligning locator tab.
  16. Align the water pipe to water pump.
  17. Seat the water feed O-seal by pushing inward toward the water pump. Take care not to tear or damage the O-ring.
  18. Lower the vehicle.

  19. Object Number: 951404  Size: SH
  20. Position the thermostat housing against the engine. Be sure that the thermostat housing pipe is properly positioned against the support bracket near the front of the engine.
  21. Install the thermostat housing to block bolts.
  22. Tighten
    Tighten the thermostat housing-to-block bolts to 10 N·m (89 lb in).

  23. Install the thermostat pipe bracket-to-engine bolt.
  24. Tighten
    Tighten the thermostat pipe bracket-to-cylinder head bolt to 8 N·m (71 lb in).


    Object Number: 951591  Size: SH
  25. Connect the electrical connector to coolant sensor.
  26. Connect the O2 sensor connector and re-attach the connector to the bracket.

  27. Object Number: 931420  Size: SH
  28. Connect the heater inlet and outlet hoses to the thermostat housing and reposition the clamps.

  29. Object Number: 931384  Size: SH
  30. Connect the lower radiator hose and clamp.
  31. Connect the surge tank return hose to the thermostat pipe.

  32. Object Number: 951395  Size: SH
  33. Install the exhaust manifold heat shield.
  34. Install the exhaust manifold shield bolts.
  35. Tighten
    Tighten the exhaust manifold heat shield bolts to 23 N·m (17 lb ft).


    Object Number: 1212661  Size: SH

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

  36. Verify the drain valves at the radiator and water pump are closed.

  37. Object Number: 1202381  Size: SH
  38. Fill the engine coolant. Refer to Cooling System Draining and Filling .
  39. Verify the repair and inspect for any leaks.