GM Service Manual Online
For 1990-2009 cars only

Thermostat Housing Crossover Replacement LMM

Removal Procedure


    Object Number: 1874992  Size: SH
  1. Remove the air cleaner. Refer to Air Cleaner Assembly Replacement .
  2. Drain the cooling system. Refer to Cooling System Draining and Filling .
  3. Disconnect the negative battery cables. Refer to Battery Negative Cable Disconnection and Connection .
  4. Remove the drive belt. Refer to Drive Belt Replacement .
  5. Disconnect the air conditioning (A/C) pressure switch electrical connector (1).
  6. Disconnect the A/C compressor clutch electrical connector (2).
  7. Remove the generator bracket. Refer to Generator Bracket Replacement .
  8. Remove the front oil fill tube. Refer to Oil Filler Tube Replacement .

  9. Object Number: 1875037  Size: SH
  10. Disconnect the engine coolant temperature (ECT) sensor electrical connectors.
  11. Remove the water outlet. Refer to Water Outlet Tube Replacement .
  12. Without disconnecting the power steering hoses, remove the power steering pump bolts and the power steering pump. Reposition the power steering pump and secure to the side. Refer to Power Steering Pump Replacement .
  13. Remove the power steering pump bracket. Refer to Air Conditioning (A/C) Compressor and Power Steering Pump Bracket Replacement .

  14. Object Number: 1874338  Size: SH
  15. Remove the bolts and wiring harness bracket at the thermostat housing.
  16. Position the bracket and wiring harness aside.
  17. Remove the cooling fan pulley. Refer to Cooling Fan Pulley Replacement .

  18. Object Number: 1335429  Size: SH
  19. Reposition the turbocharger coolant return pipe hose clamp.
  20. Remove the turbocharger coolant return pipe hose.

  21. Object Number: 1869891  Size: SH
  22. Remove the fuel line bracket bolt at the thermostat housing crossover.

  23. Object Number: 1335424  Size: SH
  24. Remove the water pump inlet pipe bolts.

  25. Object Number: 1335441  Size: SH
  26. Remove the thermostat housing crossover bolts and nuts.
  27. Remove the thermostat housing crossover, with the bypass pipe.
  28. Remove and discard the thermostat bypass pipe to water pump O-ring seal.
  29. Remove and discard the thermostat housing crossover gaskets.
  30. If necessary, perform the following:
  31. 24.1. Remove the thermostat bypass pipe from the thermostat housing crossover.
    24.2. Remove and discard the thermostat bypass pipe O-ring seal.
    24.3. Remove the thermostat cover bolts and cover.
    24.4. Remove the thermostats.
    24.5. Remove and discard the thermostat seals.
  32. If required, clean and inspect the thermostat housing. Refer to Engine Coolant Thermostat Housing Cleaning and Inspection .

Installation Procedure

    Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 1335441  Size: SH
  1. If necessary, perform the following:
  2. 1.1. Install NEW seals to the thermostats.
    1.2. Install the thermostats.
    1.3. Install the thermostat cover and bolts.

    Tighten
    Tighten the bolts to 21 N·m (15 lb ft).

    1.4. Install a NEW O-ring seal to the thermostat bypass pipe.
    1.5. Install the thermostat bypass pipe to the thermostat housing.
  3. Install a NEW thermostat bypass pipe to water pump O-ring seal.
  4. Install the thermostat housing crossover using NEW gaskets.
  5. Install the thermostat housing crossover bolts and nuts.
  6. Tighten
    Tighten the bolts/nuts to 21 N·m (15 lb ft).


    Object Number: 1335424  Size: SH
  7. Install the water pump inlet pipe bolts.
  8. Tighten
    Tighten the bolts to 21 N·m (15 lb ft).


    Object Number: 1869891  Size: SH
  9. Install the fuel line bracket bolt at the thermostat housing crossover.
  10. Tighten
    Tighten the bolt to 21 N·m (15 lb ft).


    Object Number: 1335429  Size: SH
  11. Install the turbocharger coolant return pipe hose.
  12. Position the turbocharger coolant return pipe hose clamp.

  13. Object Number: 1874338  Size: SH
  14. Install the wiring harness bracket and bolts to the thermostat housing.
  15. Tighten
    Tighten the bolts to 10 N·m (89 lb in).

  16. Install the cooling fan pulley. Refer to Cooling Fan Pulley Replacement .
  17. Install the power steering pump bracket. Refer to Air Conditioning (A/C) Compressor and Power Steering Pump Bracket Replacement .
  18. Reposition the power steering pump and install the power steering pump bolts. Refer to Power Steering Pump Replacement .

  19. Object Number: 1875037  Size: SH
  20. Install the water outlet. Refer to Water Outlet Tube Replacement .
  21. Connect the ECT sensor electrical connectors.
  22. Install the front oil fill tube. Refer to Oil Filler Tube Replacement .
  23. Install the generator bracket. Refer to Generator Bracket Replacement .

  24. Object Number: 1874992  Size: SH
  25. Connect the A/C compressor clutch electrical connector (2).
  26. Connect the A/C cut out switch electrical connector (1).
  27. Install the drive belt. Refer to Drive Belt Replacement .
  28. Connect the negative battery cables. Refer to Battery Negative Cable Disconnection and Connection .
  29. Fill the cooling system. Refer to Cooling System Draining and Filling .
  30. Install the air cleaner. Refer to Air Cleaner Assembly Replacement .