GM Service Manual Online
For 1990-2009 cars only

Engine Coolant Thermostat Replacement LZ4

Removal Procedure


    Object Number: 1583645  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. Reposition the radiator outlet hose clamp at the thermostat housing.
  4. Remove the radiator outlet hose from the thermostat housing.

  5. Object Number: 1556817  Size: SH
  6. Remove the thermostat housing bolt/stud.
  7. Remove the thermostat housing and gasket.
  8. Remove the thermostat.
  9. Clean the gasket surfaces.

Installation Procedure


    Object Number: 1556817  Size: SH
  1. Install a NEW thermostat.
  2. Position a NEW gasket and the thermostat housing to the engine block.
  3. Notice: Refer to Fastener Notice in the Preface section.

  4. Install the thermostat housing bolt/stud.
  5. Tighten
    Tighten the bolt/stud to 10 N·m (89 lb in).


    Object Number: 1583645  Size: SH
  6. Install the radiator outlet hose to the thermostat housing.
  7. Position the radiator outlet hose clamp at the thermostat housing.
  8. Install the air cleaner outlet duct. Refer to Air Cleaner Outlet Duct Replacement.
  9. Fill the cooling system. Refer to Cooling System Draining and Filling.
  10. Inspect the system for leaks.

Engine Coolant Thermostat Replacement LAT, LE5

Removal Procedure


    Object Number: 1812217  Size: SH
  1. Drain the cooling system. Refer to Cooling System Draining and Filling .
  2. Reposition the radiator outlet hose clamp at the thermostat cover.
  3. Remove the radiator outlet hose from the thermostat cover.

  4. Object Number: 1713064  Size: SH
  5. Remove the thermostat cover bolts and cover.
  6. Remove the thermostat.
  7. Remove and discard the thermostat cover O-ring seal.

Installation Procedure


    Object Number: 1713064  Size: SH
  1. Install a NEW thermostat cover O-ring seal.
  2. Install the thermostat.
  3. Notice: Refer to Fastener Notice in the Preface section.

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


    Object Number: 1812217  Size: SH
  6. Install the radiator outlet hose to the thermostat cover.
  7. Position the radiator outlet hose clamp at the thermostat cover.
  8. Fill the cooling system. Refer to Cooling System Draining and Filling .

Engine Coolant Thermostat Replacement LY7

Removal Procedure


    Object Number: 1846153  Size: SH
  1. Partially drain the cooling system. Refer to Cooling System Draining and Filling .
  2. Remove the radiator outlet hose from the thermostat housing.
  3. Remove the heater inlet and outlet hoses.
  4. Remove the surge tank outlet hose.
  5. Remove the thermostat housing bolts (1).
  6. Remove the housing.
  7. Remove the thermostat (2) and discard the thermostat gasket.

Installation Procedure


    Object Number: 1846153  Size: SH
  1. Install the thermostat (2) with a NEW thermostat gasket.
  2. Notice: Refer to Fastener Notice in the Preface section.

  3. Install the thermostat housing bolts (1).
  4. Tighten
    Tighten the thermostat housing bolts to 10 N·m (89 lb in).

  5. Install the surge tank outlet hose.
  6. Install the heater inlet and outlet hoses.
  7. Install the radiator outlet hose to the thermostat housing.
  8. Fill the cooling system. Refer to Cooling System Draining and Filling .