GM Service Manual Online
For 1990-2009 cars only

Important: The intake manifold comprises of an upper and lower section. Some service procedures only require the removal of the upper intake manifold (e.g. fuel injector/spark plug servicing), while other service procedures require the removal of both the upper and lower manifold as a complete assembly (e.g. cylinder head/s). If the complete assembly needs to be removed, refer to Lower Intake Manifold Replacement .

Removal Procedure

    Caution: Refer to Battery Disconnect Caution in the Preface section.


    Object Number: 1795237  Size: SH
  1. Disconnect the battery negative cable.
  2. Remove the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement .

  3. Object Number: 1795371  Size: SH
  4. The following precautions must be followed when disconnecting the throttle body wiring connector:
  5. • Do not use any mechanical device such as a screwdriver to disengage the harness connector (1) from the throttle body (2).
    • When retracting the throttle wiring connector lock (3), take care not to disengage the lock from the connector.
    • Do not pull on the connector wires.
  6. Retract the throttle body wiring connector lock (3).
  7. While pressing the connector latch in the direction of the arrow (4), disconnect the throttle body wiring connector.

  8. Object Number: 1795373  Size: SH
  9. Disconnect the positive crankcase ventilation (PCV) hose (1), evaporative (EVAP) emission purge vacuum hose (2).
  10. Remove the water outlet port-to-surge tank pipe bracket retaining bolts (3).
  11. Remove the EVAP emission purge solenoid bracket retaining bolt (4).

  12. Object Number: 1795375  Size: SH
  13. Disconnect the wiring harness connector from the intake manifold tuning control (IMTC) solenoid.

  14. Object Number: 1795382  Size: SH
  15. Remove the engine wiring harness mount bracket.
  16. Move all the necessary parts clear of the upper intake manifold assembly.

  17. Object Number: 1795385  Size: SH

    Important: When the upper intake manifold is removed, plug each of the lower intake runner openings with lint free cloth, to stop the entry of foreign material into the engine.

  18. Remove the four long (3) and two short bolts (2) attaching the upper intake manifold (1) to the cylinder heads and lower intake manifold.
  19. Important: Do not reuse the upper to lower intake manifold gaskets.

  20. Lift the upper intake manifold clear from the lower half and then remove the upper intake manifold from the engine.
  21. Remove and discard the upper to lower intake manifold gaskets (4).
  22. Remove the IMTC solenoid (5) and the throttle body assembly (6), if necessary.

Cleaning Procedure

Important: Due to the aluminium alloy construction of the intake manifold, wire brushes and steel scrapers must not be used during the cleaning process, as damage to sealing surfaces may occur. Use of a wooden or plastic scraper is preferred.

  1. Clean mating surfaces ensuring any gasket material is removed.
  2. Clean the manifold using a suitable solvent.
  3. Dry the manifold with compressed air.

Inspection Procedure


    Object Number: 1795386  Size: SH
  1. Inspect the intake manifold for the following fault conditions:
  2. • Damaged sealing and mating surfaces
    • Damaged lower intake manifold gasket
    • Damage or excessive debris on the threaded and through holes
    • Cracks or damage to the intake manifold body
  3. Place a straight edge (1) across the upper intake manifold sealing surface (2).
  4. Using a feeler gauge (3), measure the clearance between the manifold and the straight edge.
  5. If the clearance between the upper intake manifold sealing surface and the straight edge exceeds the specified maximum warpage, replace the manifold.
  6. Specification
    Upper manifold maximum warpage : 0.05 mm


    Object Number: 1795388  Size: SH
  7. Place a straight edge (1) across the lower intake manifold sealing  (2).
  8. Using a feeler gauge (3), measure the clearance between the manifold and the straight edge.
  9. If the clearance between the lower intake manifold sealing surface and the straight edge exceeds the specified maximum warpage, replace the manifold.
  10. Specification
    Lower manifold maximum warpage : 0.05 mm

Installation Procedure


    Object Number: 1795385  Size: SH
  1. Installation should follow the removal procedure in the reverse order, noting the following.
  2. Only new gaskets are to be fitted between the upper and lower intake manifolds.

    Notice: Refer to Fastener Notice in the Preface section.

    Important: Tighten the intake manifold bolts in a circular pattern starting at the center bolt and moving outward.

  3. Install the upper intake manifold.
  4. Tighten
    Tighten the upper intake manifold to lower intake manifold and cylinder head attaching bolts to 23 N·m (17 lb ft).


    Object Number: 1795373  Size: SH
  5. Connect the IMTC connector.
  6. Connect the throttle body connector.
  7. Install the EVAP emission purge solenoid bracket retaining bolt (4).
  8. Install the water outlet port-to-surge tank pipe bracket retaining bolts (3).
  9. Connect the EVAP emission vacuum hose (2) and PCV hose (1) to the upper intake manifold.
  10. Install the engine wiring harness mount bracket.

  11. Object Number: 1795237  Size: SH
  12. Install the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement .
  13. Connect the battery negative cable.