GM Service Manual Online
For 1990-2009 cars only

Upper Intake Manifold Cleaning Procedure

  1. Remove any remaining gasket and/or gasket material from the following:
  2. • Throttle body
    • Intake manifold
  3. Clean the following intake manifold areas in solvent.
  4. • Intake manifold gasket sealing areas
    • Intake manifold passages
    • Brake booster hose passage
    • Evaporative emission (EVAP) solenoid passage
    • Positive crankcase ventilation (PCV) vacuum hose passages
    • Barometric pressure (BARO) sensor passage

    Caution: Refer to Safety Glasses Caution in the Preface section.

  5. Dry the upper intake manifold and throttle body with compressed air.

Inspection Procedure


    Object Number: 1866909  Size: SH
  1. Inspect the upper intake manifold for the following conditions:
  2. • Damage, debris or restrictions to the BARO sensor mounting port
    • Damage, debris or restrictions to the brake vacuum booster hose port
    • Damage to the throttle body bolt holes
    • Damage, debris or restrictions to the PCV system hose ports

    Object Number: 1866910  Size: SH
  3. Inspect the upper intake manifold for the following conditions:
  4. • Damage to the intake manifold bolt bosses
    • Damage to the EVAP purge solenoid mounting boss
    • Damage, debris or restrictions to the EVAP purge solenoid port
    • Damage, debris or restrictions in the vacuum passage

    Object Number: 1866912  Size: SH
  5. Inspect the upper intake manifold for the following conditions:
  6. • Damage, debris or restrictions to the intake manifold opening cover port (1)
    • Damage to the intake manifold opening cover

    Object Number: 1866913  Size: SH
  7. Inspect the upper intake manifold for the following conditions:
  8. • Gouges or damage to the upper intake manifold sealing surfaces (1)
    • Damage to the gasket sealing surface (2) for the throttle body

    Object Number: 1866914  Size: SH
  9. Inspect the upper intake manifold sealing surface for warpage.
  10. 5.1. Locate a straight edge across the upper-to-lower intake manifold sealing surface.
    5.2. Insert a feeler gage between the upper intake manifold and the straight edge. An upper intake manifold with warpage in excess of 0.05 mm (0.020 in) must be replaced.
  11. Repair or replace the upper intake manifold as necessary.

Lower Intake Manifold Cleaning Procedure

  1. Remove any remaining gasket and/or gasket material from the following:
  2. • Upper-to-lower intake manifold sealing surface
    • Cylinder head-to-lower intake manifold sealing surface
  3. Clean the following intake manifold areas in solvent.
  4. • Intake manifold gasket sealing surfaces
    • Intake manifold passages

    Caution: Refer to Safety Glasses Caution in the Preface section.

  5. Dry the intake manifold with compressed air.

Inspection Procedure


    Object Number: 1866916  Size: SH
  1. Inspect the lower intake manifold for the following conditions:
  2. • Damage, debris or restrictions to the lower intake manifold ports
    • Damage to the fuel rail mounting bolt holes
    • Damage to the fuel rail

    Object Number: 1866918  Size: SH
  3. Inspect the lower intake manifold for the following conditions:
  4. • Gouges or damage to the intake manifold sealing surfaces
    • Damage to the lower intake manifold bolt bosses
    • Damage to the fuel injector ports

    Object Number: 1866927  Size: SH
  5. Inspect the lower intake manifold sealing surfaces for warpage.
  6. 3.1. Locate a straight edge across the lower intake manifold sealing surfaces.
    3.2. Insert a feeler gage between the lower intake manifold and the straight edge. A lower intake manifold with warpage in excess of 0.5 mm (0.020 in) must be replaced.
  7. Repair or replace the lower intake manifold as necessary.

Intake Manifold Cleaning and Inspection LY7

Upper Intake Manifold Cleaning Procedure

  1. Remove any remaining gasket and/or gasket material from the following:
  2. • Throttle body
    • Intake manifold
  3. Clean the following intake manifold areas in solvent.
  4. • Intake manifold gasket sealing areas
    • Intake manifold passages
    • Brake booster hose passage
    • Evaporative emission (EVAP) solenoid passage
    • Positive crankcase ventilation (PCV) vacuum hose passages
    • Barometric pressure (BARO) sensor passage

    Warning: Refer to Safety Glasses Warning in the Preface section.

  5. Dry the upper intake manifold and throttle body with compressed air.

Inspection Procedure


    Object Number: 1866909  Size: SH
  1. Inspect the upper intake manifold for the following conditions:
  2. • Damage, debris or restrictions to the BARO sensor mounting port
    • Damage, debris or restrictions to the brake vacuum booster hose port
    • Damage to the throttle body bolt holes
    • Damage, debris or restrictions to the PCV system hose ports

    Object Number: 1866910  Size: SH
  3. Inspect the upper intake manifold for the following conditions:
  4. • Damage to the intake manifold bolt bosses
    • Damage to the EVAP purge solenoid mounting boss
    • Damage, debris or restrictions to the EVAP purge solenoid port
    • Damage, debris or restrictions in the vacuum passage

    Object Number: 1866912  Size: SH
  5. Inspect the upper intake manifold for the following conditions:
  6. • Damage, debris or restrictions to the intake manifold opening cover port (1)
    • Damage to the intake manifold opening cover

    Object Number: 1866913  Size: SH
  7. Inspect the upper intake manifold for the following conditions:
  8. • Gouges or damage to the upper intake manifold sealing surfaces (1)
    • Damage to the gasket sealing surface (2) for the throttle body

    Object Number: 1866914  Size: SH
  9. Inspect the upper intake manifold sealing surface for warpage.
  10. 5.1. Locate a straight edge across the upper-to-lower intake manifold sealing surface.
    5.2. Insert a feeler gage between the upper intake manifold and the straight edge. An upper intake manifold with warpage in excess of 0.05 mm (0.020 in) must be replaced.
  11. Repair or replace the upper intake manifold as necessary.

Lower Intake Manifold Cleaning Procedure

  1. Remove any remaining gasket and/or gasket material from the following:
  2. • Upper-to-lower intake manifold sealing surface
    • Cylinder head-to-lower intake manifold sealing surface
  3. Clean the following intake manifold areas in solvent.
  4. • Intake manifold gasket sealing surfaces
    • Intake manifold passages

    Warning: Refer to Safety Glasses Warning in the Preface section.

  5. Dry the intake manifold with compressed air.

Inspection Procedure


    Object Number: 1866916  Size: SH
  1. Inspect the lower intake manifold for the following conditions:
  2. • Damage, debris or restrictions to the lower intake manifold ports
    • Damage to the fuel rail mounting bolt holes
    • Damage to the fuel rail

    Object Number: 1866918  Size: SH
  3. Inspect the lower intake manifold for the following conditions:
  4. • Gouges or damage to the intake manifold sealing surfaces
    • Damage to the lower intake manifold bolt bosses
    • Damage to the fuel injector ports

    Object Number: 1866927  Size: SH
  5. Inspect the lower intake manifold sealing surfaces for warpage.
  6. 3.1. Locate a straight edge across the lower intake manifold sealing surfaces.
    3.2. Insert a feeler gage between the lower intake manifold and the straight edge. A lower intake manifold with warpage in excess of 0.5 mm (0.020 in) must be replaced.
  7. Repair or replace the lower intake manifold as necessary.

Intake Manifold Cleaning and Inspection LCS

Lower Intake Manifold Assemble Procedure


    Object Number: 1866908  Size: SH
  1. Install the fuel injector rail.
  2. Caution: Refer to Fastener Caution in the Preface section.

  3. Install the fuel injector rail bolts and tighten to 10 N·m (89 lb in).

  4. Object Number: 1866907  Size: SH
  5. Install the fuel injector wiring harness connector.

Upper Intake Manifold Assemble Procedure


    Object Number: 1866903  Size: SH
  1. Install the intake manifold opening cover.
  2. Install the intake manifold opening cover bolts and tighten to 10 N·m (89 lb in).

  3. Object Number: 1866902  Size: SH
  4. Install the barometric pressure (BARO) sensor.
  5. Install the BARO sensor bolt and tighten to 10 N·m (89 lb in).

  6. Object Number: 1866901  Size: SH
  7. Install the NEW throttle body gasket.
  8. Install the throttle body.
  9. Install the throttle body bolts and tighten to 10 N·m (89 lb in).

  10. Object Number: 1531030  Size: SH
  11. Install the fuel rail support bracket.
  12. Install the fuel rail support bracket bolt and tighten to 10 N·m (89 lb in).

Upper to Lower Intake Manifold Assemble Procedure


    Object Number: 1866898  Size: SH

    Note: Do not reuse the upper-to-lower intake manifold gasket and the intake manifold-to-cylinder head sealing gaskets.

  1. Install the NEW upper-to-lower intake manifold gaskets.

  2. Object Number: 1866897  Size: SH
  3. Install the upper intake manifold to the lower intake manifold.

  4. Object Number: 1866896  Size: SH
  5. Install the fuel injector wiring harness bracket bolts to the upper intake manifold and tighten to 10 N·m (89 lb in).

  6. Object Number: 1866894  Size: SH
  7. Install the upper-to-lower intake manifold bolts and tighten to 23 N·m (17 lb ft).