GM Service Manual Online
For 1990-2009 cars only

Engine Coolant Thermostat 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 water housing.
  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 water housing sealing surfaces.
  2. Install the new 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 water housing.
  5. Notice: Refer to Fastener Notice 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 Replacement LY7

Removal Procedure

  1. Partially drain the cooling system. Refer to Cooling System Draining and Filling.
  2. Important: Do NOT separate the upper and lower intake manifolds.

  3. Remove the upper intake manifold with the lower intake manifold. Refer to Lower Intake Manifold Replacement.
  4. Disconnect the surge tank hose from the thermostat.

  5. Object Number: 887731  Size: SH
  6. Remove the coolant pipe/thermostat housing bolt (2).
  7. Remove the coolant pipe upper bolt (7).
  8. Remove the coolant inlet pipe (4) from the thermostat.

  9. Object Number: 1303007  Size: SH
  10. Remove the thermostat bolts.
  11. Remove the thermostat and discard the thermostat seal.

Installation Procedure


    Object Number: 1303007  Size: SH
  1. Install the thermostat with a NEW thermostat seal.
  2. Notice: Refer to Fastener Notice in the Preface section.

  3. Install the thermostat bolts.
  4. Tighten
    Tighten the thermostat bolts to 10 N·m (89 lb in).


    Object Number: 887731  Size: SH
  5. Install the coolant pipe (4), NEW seal, and fasteners (2 and 7). Refer to Engine Coolant Inlet Pipe Replacement.
  6. Install the surge tank hose to the thermostat.
  7. Install the upper intake manifold with the lower intake manifold. Refer to Lower Intake Manifold Replacement.
  8. Fill the cooling system. Refer to Cooling System Draining and Filling.