GM Service Manual Online
For 1990-2009 cars only

Engine Coolant Thermostat Housing Replacement LNF

Removal Procedure

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


    Object Number: 1212666  Size: SH
  1. Drain the cooling system. Refer to Cooling System Draining and Filling.
  2. Caution: Refer to Fastener Caution in the Preface section.

  3. Drain the coolant from the engine block at the water pump drain. After the coolant has drained, tighten the drain bolt.
  4. Tighten
    Tighten the drain plug to 20 N·m (15 lb ft).

  5. Lower the vehicle.
  6. Remove the air inlet grille panel. Refer to Air Inlet Grille Panel Replacement.

  7. Object Number: 1826284  Size: SH
  8. Disconnect the engine wiring harness electrical connector (3) from the engine coolant temperature (ECT) sensor.

  9. Object Number: 1713085  Size: SH
  10. Remove the ECT sensor, if necessary.

  11. Object Number: 1826444  Size: SH
  12. Reposition the radiator outlet hose clamp (2) at the thermostat housing.
  13. Remove the radiator outlet hose from the thermostat housing and reposition out of the way.
  14. Remove the exhaust manifold. Refer to Exhaust Muffler Replacement.

  15. Object Number: 1826795  Size: SH
  16. Reposition the heater inlet and outlet hose clamps at the thermostat housing pipes.
  17. Disconnect the heater inlet (2) and outlet (1) hoses from the thermostat housing pipes.

  18. Object Number: 1713067  Size: SH
  19. Remove the thermostat housing bolts.
  20. Note: Twist the water transfer pipe while pulling in order to remove it from the water pump.

  21. Remove the thermostat housing from the vehicle.
  22. Remove the water transfer pipe from the thermostat housing, if necessary.
  23. Remove and discard the water transfer pipe O-ring seals, if necessary.

  24. Object Number: 1713064  Size: SH
  25. Remove the thermostat housing cover bolts and cover, if necessary.
  26. Remove the thermostat, if necessary.
  27. Remove and discard the thermostat housing O-ring seal, if necessary.
  28. 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: 1713064  Size: SH
  1. Install a NEW thermostat housing cover O-ring seal into the recess groove.
  2. Install the thermostat, if necessary.
  3. Caution: Refer to Fastener Caution in the Preface section.

  4. Install the thermostat housing cover bolts, if necessary.
  5. Tighten
    Tighten the bolts to 10 N·m (89 lb in).

  6. Install a NEW thermostat housing to engine gasket onto the thermostat housing.
  7. Load the thermostat housing assembly into position while the vehicle is lowered.
  8. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle.

  9. Object Number: 1713067  Size: SH

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

  10. Install NEW O-ring seals onto the water feed pipe.
  11. Note: Lubricate the O-rings with coolant ONLY.

  12. Install the water feed pipe into the thermostat housing aligning locator tab.
  13. Align the water pipe to water pump.
  14. Seat the water feed O-ring seal by pushing inward toward the water pump. Take care not to tear or damage the O-ring.
  15. Lower the vehicle.
  16. Position the thermostat housing against the engine.
  17. Install the thermostat housing bolts.
  18. Tighten
    Tighten the bolts to 10 N·m (89 lb in).


    Object Number: 1826795  Size: SH
  19. Connect the heater inlet (2) and outlet (1) hoses to the thermostat housing pipes.
  20. Position the heater inlet and outlet hose clamps at the thermostat housing pipes.
  21. Install the exhaust manifold. Refer to Exhaust Muffler Replacement.

  22. Object Number: 1826444  Size: SH
  23. Install the radiator outlet hose to the thermostat housing.
  24. Position the radiator outlet hose clamp (2) at the thermostat housing.

  25. Object Number: 1713085  Size: SH
  26. If reinstalling the old sensor, coat the threads with sealant. Refer to Adhesives, Fluids, Lubricants, and Sealers.
  27. Install the ECT sensor, if necessary.
  28. Tighten
    Tighten the sensor to 20 N·m (15 lb ft).


    Object Number: 1826284  Size: SH
  29. Connect the engine wiring harness electrical connector (3) to the ECT sensor.
  30. Install the air inlet grille panel. Refer to Air Inlet Grille Panel Replacement.

  31. Object Number: 1212666  Size: SH

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

  32. Verify the drain plugs at the radiator and water pump are tightened.
  33. Fill the cooling system. Refer to Cooling System Draining and Filling.
  34. Lower the vehicle.
  35. Inspect for any leaks.

Engine Coolant Thermostat Housing Replacement LE5

Removal Procedure

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


    Object Number: 1212666  Size: SH
  1. Drain the cooling system. Refer to Cooling System Draining and Filling.
  2. Caution: Refer to Fastener Caution in the Preface section.

  3. Drain the coolant from the engine block at the water pump drain. After the coolant has drained, tighten the drain bolt.
  4. Tighten
    Tighten the drain plug to 20 N·m (15 lb ft).

  5. Lower the vehicle.
  6. Remove the air inlet grille panel. Refer to Air Inlet Grille Panel Replacement.

  7. Object Number: 1591858  Size: SH
  8. Disconnect the engine wiring harness electrical connector (6) from the engine coolant temperature (ECT) sensor.

  9. Object Number: 1713085  Size: SH
  10. Remove the ECT sensor, if necessary.

  11. Object Number: 1714037  Size: SH
  12. Reposition the radiator outlet hose clamp at the thermostat housing.
  13. Remove the radiator outlet hose from the thermostat housing.
  14. Remove the radiator outlet hose clip (1) from the outlet hose bracket.

  15. Object Number: 1593131  Size: SH
  16. Remove the exhaust heat shield bolts.
  17. Remove the exhaust heat shield.

  18. Object Number: 1592522  Size: SH
  19. Reposition the heater inlet and outlet hose clamps at the thermostat housing pipes.
  20. Disconnect the heater inlet (2) and outlet (1) hoses from the thermostat housing pipes.

  21. Object Number: 1713067  Size: SH
  22. Remove the thermostat housing bolts.
  23. Note: Twist the water transfer pipe while pulling in order to remove it from the water pump.

  24. Remove the thermostat housing from the vehicle.
  25. Remove the water transfer pipe from the thermostat housing, if necessary.
  26. Remove and discard the water transfer pipe O-ring seals, if necessary.

  27. Object Number: 1713064  Size: SH
  28. Remove the thermostat housing cover bolts and cover, if necessary.
  29. Remove the thermostat, if necessary.
  30. Remove and discard the thermostat housing O-ring seal, if necessary.
  31. 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: 1713064  Size: SH
  1. Install a NEW thermostat housing cover O-ring seal into the recess groove.
  2. Install the thermostat, if necessary.
  3. Caution: Refer to Fastener Caution in the Preface section.

  4. Install the thermostat housing cover bolts, if necessary.
  5. Tighten
    Tighten the bolts to 10 N·m (89 lb in).

  6. Install a NEW thermostat housing to engine gasket onto the thermostat housing.
  7. Load the thermostat housing assembly into position while the vehicle is lowered.
  8. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle.

  9. Object Number: 1713067  Size: SH

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

  10. Install NEW O-ring seals onto the water feed pipe.
  11. Note: Lubricate the O-rings with coolant ONLY.

  12. Install the water feed pipe into the thermostat housing aligning locator tab.
  13. Align the water pipe to water pump.
  14. Seat the water feed O-ring seal by pushing inward toward the water pump. Take care not to tear or damage the O-ring.
  15. Lower the vehicle.
  16. Position the thermostat housing against the engine.
  17. Install the thermostat housing bolts.
  18. Tighten
    Tighten the bolts to 10 N·m (89 lb in).


    Object Number: 1592522  Size: SH
  19. Connect the heater inlet (2) and outlet (1) hoses to the thermostat housing pipes.
  20. Position the heater inlet and outlet hose clamps at the thermostat housing pipes.

  21. Object Number: 1593131  Size: SH
  22. Install the exhaust heat shield.
  23. Install the exhaust heat shield bolts.
  24. Tighten
    Tighten the bolts to 23 N·m (17 lb ft).


    Object Number: 1714037  Size: SH
  25. Install the radiator outlet hose to the thermostat housing.
  26. Reposition the radiator outlet hose clamp at the thermostat housing.
  27. Install the radiator outlet hose clip (1) to the outlet hose bracket.

  28. Object Number: 1713085  Size: SH
  29. If reinstalling the old sensor, coat the threads with sealant. Refer to Adhesives, Fluids, Lubricants, and Sealers.
  30. Install the ECT sensor, if necessary.
  31. Tighten
    Tighten the sensor to 20 N·m (15 lb ft).


    Object Number: 1591858  Size: SH
  32. Connect the engine wiring harness electrical connector (6) to the ECT sensor.
  33. Install the air inlet grille panel. Refer to Air Inlet Grille Panel Replacement.

  34. Object Number: 1212666  Size: SH

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

  35. Verify the drain plugs at the radiator and water pump are tightened.
  36. Fill the cooling system. Refer to Cooling System Draining and Filling.
  37. Lower the vehicle.
  38. Inspect for any leaks.