GM Service Manual Online
For 1990-2009 cars only

Engine Coolant Thermostat Housing Replacement LA3, LY9

Removal Procedure

  1. Remove the coolant outlet pipe. Refer to Engine Coolant Outlet Pipe Replacement .
  2. Remove the intake manifold. Refer to Intake Manifold Replacement in Engine Mechanical-2.6L and 3.2L.

  3. Object Number: 142124  Size: SH
  4. Remove the thermostat housing bolts (1).
  5. Remove the thermostat housing (2) with thermostat, from the engine.
  6. Remove and discard the seal ring.
  7. Remove the thermostat from the thermostat housing. Refer to Engine Coolant Thermostat Replacement .

Installation Procedure

  1. Install the thermostat into the thermostat housing. Refer to Engine Coolant Thermostat Replacement .

  2. Object Number: 142124  Size: SH
  3. Install a new seal ring.
  4. Position the thermostat housing (2) with thermostat, to the engine.
  5. Notice: Refer to Fastener Notice in the Preface section.

  6. Install the thermostat housing bolts (1).
  7. Tighten
    Tighten the thermostat housing bolts to 20 N·m (15 lb ft).

  8. Install the intake manifold. Refer to Intake Manifold Replacement in Engine Mechanical-2.6L and 3.2L.
  9. Install the coolant outlet pipe. Refer to Engine Coolant Outlet Pipe Replacement .

Engine Coolant Thermostat Housing Replacement LY7

Tools Required

J 28410 Gasket Remover

Removal Procedure

  1. Disconnect the heater hoses from the heater core. Refer to Heater Inlet Hose Replacement and Heater Outlet Hose Replacement .
  2. Remove the thermostat. Refer to Engine Coolant Thermostat Replacement .

  3. Object Number: 902889  Size: SH
  4. Remove the thermostat housing bolts.
  5. Remove the thermostat housing with the heater pipes, hoses and bolts.
  6. Carefully clean the sealing surfaces with a plastic gasket scraper such as J 28410 or equivalent.

Installation Procedure

  1. Assemble the heater pipes and hoses to the thermostat housing.
  2. Install a new gasket to the thermostat housing.
  3. Install the thermostat housing bolts to the thermostat housing.
  4. Partially install the thermostat housing bolts in order to retain the gasket.


    Object Number: 902889  Size: SH
  5. Install the thermostat housing with the heater pipes, heater hoses, gasket and bolts.
  6. Notice: Refer to Fastener Notice in the Preface section.

  7. Install the thermostat housing bolts.
  8. Tighten
    Tighten the thermostat housing bolts to 20 N·m (15 lb ft).

  9. Install the thermostat. Refer to Engine Coolant Thermostat Replacement .
  10. Connect the heater hoses to the heater core. Refer to Heater Inlet Hose Replacement and Heater Inlet Hose Replacement .

Engine Coolant Thermostat Housing Replacement LS6

Removal Procedure

Important: The water pump inlet (thermostat housing) and thermostat MUST be replaced as an assembly. The thermostat is not serviceable separately.


    Object Number: 370076  Size: SH
  1. Drain the cooling system. Refer to Cooling System Draining and Filling .
  2. Remove the cooling fan assembly. Refer to Engine Cooling Fan Replacement .
  3. Reposition the outlet hose clamp at the water pump inlet.
  4. Remove the outlet hose from the water pump inlet.
  5. Remove the thermostat housing bolts.
  6. Remove the thermostat housing.

  7. Object Number: 370073  Size: SH
  8. The thermostat and O-ring seal are integral to the thermostat housing.

Installation Procedure


    Object Number: 370073  Size: SH
  1. Install a new thermostat housing.
  2. Ensure that the new thermostat housing has an O-ring seal and is in the groove correctly.

  3. Object Number: 370076  Size: SH
  4. Install the thermostat housing (with thermostat).
  5. 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.

  6. Install the thermostat housing bolts.
  7. Tighten
    Tighten the thermostat housing bolts to 15 N·m (11 lb ft).

  8. Install the outlet hose to the thermostat housing.
  9. Position the outlet hose clamp at the thermostat housing.
  10. Install the cooling fan assembly. Refer to Engine Cooling Fan Replacement .
  11. Fill the cooling system. Refer to Cooling System Draining and Filling .