GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1998 🢒 Corvette 🢒 Engine 🢒 Engine Mechanical - 5.7L 🢒 Intake Manifold Cleaning and Inspection

Cleaning Procedure


    Object Number: 58838 Size: SH
  1. Remove the Manifold Absolute Pressure (MAP) sensor from the rear of the intake manifold (the MAP sensor is to be reinstalled upon completion of the cleaning and inspection procedures).
  2. Inspect the sealing grommet on the MAP sensor. The grommet should not be torn or damaged.

    3. Object Number: 178557 Size: SH

    Important: Do not reuse the intake manifold-to-cylinder head sealing gaskets.

  3. Remove and discard the intake manifold-to-cylinder head gaskets.
  4. Remove the fuel rail with injectors.

    5. Object Number: 43567 Size: SH
  5. Remove the throttle body and gasket and discard the throttle body gasket.

    6. Refer to Throttle Body Removal .

  6. Clean the intake manifold in solvent.
    7. • Clean the intake manifold gasket grooves.
    • Clean the intake manifold vacuum passages at the rear of the intake.

    Caution: Wear safety glasses in order to avoid eye damage.

  7. Dry the intake manifold with compressed air.
  8. Upon installation of the intake manifold, install NEW manifold-to-cylinder head gaskets.

    9. Object Number: 58838 Size: SH
  9. Install the MAP sensor.

Inspection Procedure


    Object Number: 43567 Size: SH
  1. Inspect the throttle body bolt inserts for looseness or damaged threads.

    2. Object Number: 43568 Size: SH
  2. Inspect the fuel rail bolt inserts for looseness or damaged threads.
  3. Inspect the intake manifold vacuum passages for debris or restrictions.

    4. Object Number: 58838 Size: SH

    Important: The rear Manifold Absolute Pressure (MAP) sensor housing is retained to the intake manifold by push-in-place snap lock design.

    The rear MAP sensor housing is sealed at the intake manifold by an O-ring seal.

  4. Inspect the rear MAP sensor housing.
    5. • Inspect for damaged or broken vacuum fittings, damaged MAP sensor mounting bore, or broken MAP sensor retaining tab.
    • Inspect the rear MAP sensor housing for looseness or poor sealing to the intake manifold. Repair or replace the components as necessary.
  5. Inspect the composite intake manifold assembly for cracks or damage.

    6. Inspect the areas between the intake runners.

  6. Inspect all the gasket sealing surfaces and grooves for cracking or damage.

    7. Object Number: 43568 Size: SH
  7. Inspect the fuel injector bores for excessive scoring or damage.
  8. Inspect the intake manifold cylinder head deck for warpage.
    9. 8.1. Locate a straight edge across the intake manifold cylinder head deck surface.
    8.2. Insert a feeler gauge between the intake manifold and the straight edge.

    A intake manifold with warpage in excess of 0.5 mm (0.020 in), must be replaced.

  9. Upon completion of inspection, install the MAP sensor to the manifold.