GM Service Manual Online
For 1990-2009 cars only

Engine Coolant Thermostat Housing Replacement LH2

Removal Procedure


    Object Number: 1201091  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 Outlet Duct Replacement.
  3. Remove the radiator hose from the thermostat housing. Refer to Radiator Outlet Hose Replacement.
  4. Remove the heater hose from the thermostat housing. Refer to Heater Outlet Hose Replacement.
  5. Remove the thermostat housing bolts.
  6. Remove the thermostat housing (1) with thermostat (3), from the tank.
  7. Remove and discard the seal ring (2).
  8. Remove the thermostat from the thermostat housing.

Installation Procedure


    Object Number: 1201091  Size: SH
  1. Clean the thermostat housing and tank sealing surfaces.
  2. Install the thermostat to the thermostat housing.
  3. Install the new seal (2) to the thermostat housing.
  4. Install the thermostat housing (1) with the thermostat (3) and the seal (2) to the tank.
  5. Caution: Refer to Fastener Caution in the Preface section.

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

  8. Install the heater hose to the thermostat housing. Refer to Heater Outlet Hose Replacement.
  9. Install the radiator hose to the thermostat housing. Refer to Radiator Outlet Hose Replacement.
  10. Install the air cleaner outlet duct. Refer to Air Cleaner Outlet Duct Replacement.
  11. Fill the cooling system. Refer to Cooling System Draining and Filling.

Engine Coolant Thermostat Housing Replacement LY7

Special Tools

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 in order to retain the gasket.
  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. Caution: Refer to Fastener Caution 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.