GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2008 🢒 CTS 🢒 Engine 🢒 Engine Mechanical - 2.8L, 3.0L, 3.2L, or 3.6L 🢒 Intake Manifold Cleaning and Inspection

Intake Manifold Cleaning and Inspection LY7/LP1

Upper Intake Manifold Cleaning Procedure
  1. Remove any remaining gasket and/or gasket material from the following:
    2. • Throttle body
    • Intake manifold
  2. Clean the following intake manifold areas in solvent.
    3. • 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.

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

Inspection Procedure

    Object Number: 1888155 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: 1888156 Size: SH
  2. Inspect the upper intake manifold for the following conditions:
    3. • 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: 1888157 Size: SH
  3. Inspect the upper intake manifold for the following conditions:
    4. • Damage to the communicator valve mounting bosses
    • Damage, debris or restrictions to the communicator valve port
    • Damage to the communicator valve components

    Object Number: 1888158 Size: SH
  4. Inspect the upper intake manifold for the following conditions:
    5. • Gouges or damage to the upper intake manifold sealing surfaces
    • Damage to the gasket sealing surface for the throttle body

    Object Number: 1211106 Size: SH
  5. Inspect the upper intake manifold sealing surface for warpage.
    6. 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 0.50 mm (0.020 in) must be replaced.
  6. 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
  2. Clean the following intake manifold areas in solvent.
    3. • Intake manifold gasket sealing surfaces
    • Intake manifold passages

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

  3. Dry the intake manifold with compressed air.

Inspection Procedure

    Object Number: 1211107 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: 1211110 Size: SH
  2. Inspect the lower intake manifold for the following conditions:
    3. • 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: 1211113 Size: SH
  3. Inspect the lower intake manifold sealing surfaces for warpage.
    4. 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.
  4. Repair or replace the lower intake manifold as necessary.

Intake Manifold Cleaning and Inspection LLT

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

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

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

Inspection Procedure

    Object Number: 1978003 Size: SH
  1. Inspect the upper intake manifold for the following conditions:
    2. • 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
    • Damage to the gasket sealing surface for the intake manifold cover

    Object Number: 1978004 Size: SH
  2. Inspect the upper intake manifold for the following conditions:
    3. • 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: 1507473 Size: SH
  3. Inspect the intake manifold for the following conditions:
    4. • Gouges or damage to the intake manifold sealing surfaces
    • Damage to the gasket sealing surface for the throttle body

    Object Number: 1978006 Size: SH
  4. Inspect the upper intake manifold sealing surface for warpage.
    5. 4.1. Locate a straight edge across the intake manifold sealing surface.
    4.2. Insert a feeler gage between the upper intake manifold and the straight edge. An intake manifold with warpage in excess of 0.50 mm (0.020 in) must be replaced.
  5. Repair or replace the upper intake manifold as necessary.