GM Service Manual Online
For 1990-2009 cars only

Engine Coolant Thermostat Replacement 3.8L

Removal Procedure

Tools Required

J 38185 Hose Clamp Pliers

  1. Remove the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement in Engine Mechanical - 3.8L.
  2. Partially drain the cooling system. Refer to Cooling System Draining and Filling .

  3. Object Number: 308970  Size: SH
  4. Use the J 38185 in order to reposition the hose clamp at the water outlet housing.
  5. Disconnect the radiator hose from the water outlet housing.

  6. Object Number: 153572  Size: SH
  7. Remove the water outlet housing bolts.
  8. Remove the water outlet housing and gasket.
  9. Remove the thermostat.
  10. Inspect and clean the mating surfaces.
  11. • Water outlet housing
    • Lower intake manifold

Installation Procedure

Tools Required

J 38185 Hose Clamp Pliers


    Object Number: 153572  Size: SH
  1. Install the thermostat.
  2. Install the gasket and the water outlet housing.
  3. 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.

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


    Object Number: 308970  Size: SH
  6. Connect the radiator hose to the water outlet housing.
  7. Use the J 38185 in order to reposition install the hose clamp to the water outlet housing.
  8. Fill the cooling system. Refer to Cooling System Draining and Filling .
  9. Install the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement in Engine Mechanical - 3.8L.
  10. Inspect for leaks.

Engine Coolant Thermostat Replacement 3.4L

Removal Procedure

Tools Required

J 38185 Hose Clamp Pliers

  1. Carefully remove the throttle body air inlet duct.
  2. Partially drain the cooling system. Refer to Cooling System Draining and Filling .

  3. Object Number: 70064  Size: SH
  4. Use the J 38185 in order to reposition the hose clamp at the thermostat housing.
  5. Disconnect the radiator hose from the thermostat housing.
  6. Remove the exhaust crossover pipe. Refer to Exhaust Crossover Replacement in Engine Mechanical - 3.4L.

  7. Object Number: 30962  Size: SH
  8. Remove the thermostat housing bolts.
  9. Remove the thermostat housing and the gasket.

  10. Object Number: 30995  Size: SH
  11. Remove the thermostat.
  12. Clean the mating surfaces.

Installation Procedure


    Object Number: 30995  Size: SH
  1. Install the thermostat.

  2. Object Number: 30962  Size: SH
  3. Install the thermostat housing and the gasket.

  4. Object Number: 70064  Size: SH

    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.

  5. Install the thermostat housing bolts.
  6. Tighten
    Tighten the thermostat housing bolts to 25 N·m (18 lb ft).

  7. Install the exhaust crossover pipe. Refer to Exhaust Crossover Replacement in Engine Mechanical - 3.4L.
  8. Connect the radiator hose to the thermostat housing.
  9. Use the J 38185 in order to reposition and install the hose clamp at the thermostat housing.
  10. Carefully install the throttle body air inlet duct.
  11. Fill the cooling system. Refer to Cooling System Draining and Filling .
  12. Inspect for leaks.