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Home >> GMC >> 2005 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 223 (Engine Mechanical - 3.6L (Ly7) (4 Of 6)) >> Off-Vehicle Repair Instructions - Part 2 >> Intake Manifold Cleaning and Inspection >> Inspection Procedure

Inspection Procedure

WARNING: This page is about a different car, the 2005 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
    Fig 1: View Of Upper Intake Manifold Vacuum Areas
    GM1507470Courtesy of GENERAL MOTORS CORP.
  1. Inspect the upper intake manifold for the following conditions:
    • Damage, debris or restrictions to the barometric (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
    2. Fig 2: View Of Upper Intake Manifold EVAP Areas
    GM1507471Courtesy of GENERAL MOTORS CORP.
  2. Inspect the upper intake manifold for the following conditions:
    • 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
    3. Fig 3: View Of Upper Intake Manifold Communicator Valve Area
    GM1507472Courtesy of GENERAL MOTORS CORP.
  3. Inspect the upper intake manifold for the following conditions:
    • Damage to the communicator valve mounting bosses
    • Damage, debris or restrictions to the communicator valve port
    • Damage to the communicator valve components
    4. Fig 4: View Of Upper Intake Manifold Sealing Surfaces
    GM1507473Courtesy of GENERAL MOTORS CORP.
  4. Inspect the upper intake manifold for the following conditions:
    • Gouges or damage to the upper intake manifold sealing surfaces
    • Damage to the gasket sealing surface for the throttle body
    5. Fig 5: Inspecting Upper Intake Manifold Sealing Surface For Warpage
    GM1211106Courtesy of GENERAL MOTORS CORP.
  5. Inspect the upper intake manifold sealing surface for warpage.
    1. Locate a straight edge across the upper-to-lower intake manifold sealing surface.
    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.
  6. Repair or replace the upper intake manifold as necessary.


    Fig 1: Inspecting Lower Intake Manifold For Damage
    GM1211107Courtesy of GENERAL MOTORS CORP.
  1. Inspect the lower intake manifold for the following conditions:
    • Damage, debris or restrictions to the lower intake manifold ports
    • Damage to the fuel rail mounting bolt holes
    • Damage to the fuel rail
    2. Fig 2: Checking Lower Intake Manifold For Damage
    GM1211110Courtesy of GENERAL MOTORS CORP.
  2. Inspect the lower intake manifold for the following conditions:
    • Gouges or damage to the intake manifold sealing surfaces
    • Damage to the lower intake manifold bolt bosses
    • Damage to the fuel injector ports
    3. Fig 3: Measuring Lower Intake Manifold For Warpage
    GM1211113Courtesy of GENERAL MOTORS CORP.
  3. Inspect the lower intake manifold sealing surfaces for warpage.
    1. Locate a straight edge across the lower intake manifold sealing surfaces.
    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.
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