GM Service Manual Online
For 1990-2009 cars only

Engine Coolant Thermostat Housing Replacement LY7

Removal Procedure

Tools Required

J 28410 Gasket Remover

  1. Disconnect the heater hoses from the heater core. Refer to Heater Inlet Hose Replacement or 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 or Heater Outlet Hose Replacement .

Engine Coolant Thermostat Housing Replacement LS4

Tools Required

J 38185 Hose Clamp Pliers

Removal Procedure


    Object Number: 1524229  Size: SH
  1. Partially drain the cooling system. Refer to Cooling System Draining and Filling .
  2. Use the J 38185 in order to reposition the hose clamp from the water outlet housing.
  3. Remove the radiator inlet hose from the water outlet housing.

  4. Object Number: 1411896  Size: SH
  5. Remove the water outlet housing bolts (302).
  6. Remove the water outlet housing (303) and O-ring seal (304).
  7. Remove the thermostat (305).
  8. Clean and inspect the water outlet housing O-ring seal mating surfaces.

Installation Procedure

Notice: DO NOT use cooling system seal tabs, or similar compounds, unless otherwise instructed. The use of cooling system seal tabs, or similar compounds, may restrict coolant flow through the passages of the cooling system or the engine components. Restricted coolant flow may cause engine overheating and/or damage to the cooling system or the engine components/assembly.


    Object Number: 1411896  Size: SH
  1. Install the thermostat (305).
  2. Install the O-ring seal (304) and water outlet housing (303).
  3. Notice: Refer to Fastener Notice in the Preface section.

  4. Install the water outlet housing bolts (302).
  5. Tighten
    Tighten the bolts to 15 N·m (11 lb ft).


    Object Number: 1524229  Size: SH
  6. Install the radiator inlet hose to the water outlet housing.
  7. Use the J 38185 in order to reposition and install the hose clamp to the water outlet housing.
  8. Fill the cooling system. Refer to Cooling System Draining and Filling .

Engine Coolant Thermostat Housing Replacement RPOs L26/L32

Tools Required

J 38185 Hose Clamp Pliers

Removal Procedure


    Object Number: 308970  Size: SH
  1. Remove the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement .
  2. Partially drain the cooling system. Refer to Cooling System Draining and Filling .
  3. Use the J 38185 in order to reposition the hose clamp from the water outlet housing.
  4. Remove the radiator inlet hose from the water outlet housing.

  5. Object Number: 153572  Size: SH
  6. Reposition the wiring harness from the water outlet housing stud.
  7. Remove the water outlet housing bolt and the stud.
  8. Remove the water outlet housing and the gasket.
  9. Remove the thermostat.
  10. Clean and Inspect the water outlet housing gasket mating surfaces.

Installation Procedure


    Object Number: 153572  Size: SH
  1. Install the thermostat.
  2. Install the gasket and the water outlet housing.
  3. Notice: Refer to Fastener Notice in the Preface section.

  4. Install the water outlet housing bolt and the stud to the water outlet housing.
  5. Tighten
    Tighten the bolt and the stud to 27 N·m (20 lb ft).

  6. Install the wiring harness to the water outlet housing stud.

  7. Object Number: 308970  Size: SH
  8. Install the radiator inlet hose to the water outlet housing.
  9. Use the J 38185 in order to reposition and install the hose clamp to the water outlet housing.
  10. Fill the cooling system. Refer to Cooling System Draining and Filling .
  11. Install the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement .