GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Monte Carlo 🢒 Engine 🢒 Engine Mechanical - 3.8L 🢒 Lower Intake Manifold Replacement

Removal Procedure
  1. Remove the upper intake manifold. Refer to Upper Intake Manifold Replacement .
  2. Remove the generator brace. Refer to Generator Brace Replacement in Engine Electrical.

    3. Object Number: 326960 Size: SH
  3. Remove the drive belt tensioner with the mounting bracket and the heater water bypass inlet pipe. Refer to Drive Belt Tensioner Replacement .

    4. Object Number: 190556 Size: SH
  4. Remove the exhaust gas recirculation (EGR) outlet pipe bolt from the lower intake manifold.

    5. Object Number: 405984 Size: SH
  5. Remove the radiator inlet hose from the water outlet housing. Refer to Radiator Inlet Hose Replacement in Engine Cooling.

    6. Object Number: 406011 Size: SH
  6. Disconnect the engine coolant temperature (ECT) sensor electrical connector.
  7. Remove the right upper engine mount strut bracket. Refer to Engine Mount Strut Bracket Replacement - Right Upper .

    8. Object Number: 371022 Size: SH
  8. Remove the generator brace bracket bolts.
  9. Remove the generator brace bracket.

    10. Object Number: 190545 Size: SH
  10. Remove the lower intake manifold bolts.
  11. Remove the lower intake manifold.

    12. Object Number: 153573 Size: SH
  12. Remove the lower intake manifold seals.

    13. Object Number: 153574 Size: SH
  13. Remove the lower intake manifold gaskets.

    14. Object Number: 406012 Size: SH
  14. If replacing the lower intake manifold, remove the water outlet housing bolt and stud, the water outlet housing, the gasket and the thermostat.
  15. If replacing the lower intake manifold, remove the ECT sensor.
  16. Inspect the flatness of inlet flanges.
  17. Clean the intake manifold mating surfaces.
  18. Clean the intake manifold bolts and bolt holes of adhesive compound.

Installation Procedure

    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.

  1. If removed, install the ECT sensor.

    2. Tighten
    Tighten the ECT sensor to 25 N·m (18 lb ft).


    Object Number: 406012 Size: SH
  2. If removed, install the thermostat, the gasket, and the water outlet housing.
  3. Install the water outlet housing bolt and the stud.

    4. Tighten
    Tighten the bolt and stud to 27 N·m (20 lb ft).


    Object Number: 153574 Size: SH
  4. Install the lower intake manifold gaskets.

    5. Object Number: 153573 Size: SH
  5. Apply sealer GM P/N 12346286 (Canadian P/N 10953472) or equivalent to the ends of the intake manifold seals.
  6. Install the lower intake manifold seals.

    7. Object Number: 190545 Size: SH
  7. Install the lower intake manifold.

    8. Object Number: 44774 Size: SH
  8. Install the lower intake manifold bolts (1-12). Apply thread lock compound GM P/N 12345382 (Canadian P/N 10953489) or equivalent to the two hidden bolts and ensure they are installed.

    9. Tighten
    Tighten the lower intake manifold bolts in sequence to 15 N·m (11 lb ft).


    Object Number: 371022 Size: SH
  9. Install the generator brace bracket.
  10. Install the generator brace bracket bolts.

    11. Tighten
    Tighten the bolts to 50 N·m (37 lb ft).

  11. Install the right upper engine mount strut bracket. Refer to Engine Mount Strut Bracket Replacement - Right Upper .

    12. Object Number: 406011 Size: SH
  12. Connect the ECT sensor electrical connector.

    13. Object Number: 405984 Size: SH
  13. Install the radiator inlet hose to the water outlet housing. Refer to Radiator Inlet Hose Replacement in Engine Cooling.

    14. Object Number: 190556 Size: SH
  14. Install the EGR outlet pipe to the lower intake manifold.
  15. Install the EGR outlet pipe bolt to the lower intake manifold.

    16. Tighten
    Tighten the bolt to 29 N·m (21 lb ft).


    Object Number: 326960 Size: SH
  16. Install the drive belt tensioner. Refer to Drive Belt Tensioner Replacement .
  17. Install the generator brace. Refer to Generator Brace Replacement in Engine Electrical.
  18. Install the upper intake manifold. Refer to Upper Intake Manifold Replacement .
  19. Inspect for leaks.