GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2002 🢒 GMC C Sierra - 2WD 🢒 Engine 🢒 Engine Mechanical - 8.1L 🢒 Intake Manifold Replacement

Removal Procedure

Important: The intake manifold, throttle body, fuel rail, and injectors may be removed as an assembly. If not servicing the individual components, remove the manifold as a complete assembly.


    Object Number: 700979 Size: SH
  1. Loosen the clamps at the throttle body and air cleaner.
  2. Remove the air cleaner outlet duct.

    3. Object Number: 665445 Size: SH
  3. Loosen the intake manifold sight shield bolt (3).
  4. Remove the sight shield from the bracket (1).
  5. Remove the sight shield bracket (1) and nuts.
  6. Relieve the fuel system pressure. Refer to Fuel Pressure Relief in Engine Controls - 8.1L.
  7. Disconnect the fuel feed and return pipes. Refer to Metal Collar Quick Connect Fitting Service in Engine Controls - 8.1L.

    8. Object Number: 750582 Size: SH
  8. Disconnect the engine harness clips from the studs on the front of dash.
  9. Disconnect the engine harness clip from the wheelhouse splash shield.
  10. Disconnect the following electrical connectors:
    11. • Pressure cycling switch (1)
    • Surge tank switch (2)
    • Mass airflow (MAF) sensor (3)
  11. Reposition engine harness branch to top of engine.

    12. Object Number: 750529 Size: SH
  12. Remove the connector position assurance (CPA) retainer at the ignition coil harness.
  13. Disconnect the following electrical connectors:
    14. • Manifold absolute pressure (MAP) sensor (1)
    • Ignition coil harness (2)
    • Engine coolant temperature (ECT) sensor (3)

    Object Number: 750525 Size: SH
  14. Remove the engine harness bolt and studs
  15. Remove the CPA retainer at the ignition coil harness.
  16. Disconnect the following electrical connectors:
    17. • Generator (1)
    • Injector harness (2)
    • Ignition coil harness (3)
    • Throttle position (TP) sensor (4)
    • Electronic throttle control (ETC) (5)
    • Purge valve solenoid (6)
  17. Reposition the engine harness to the drivers side of the engine compartment.

    18. Object Number: 750614 Size: SH
  18. Remove the bypass valve vacuum hose (1) from the intake manifold.

    19. Object Number: 750530 Size: SH
  19. Disconnect the exhaust gas recirculation (EGR) valve electrical connector (1).

    20. Object Number: 635635 Size: SH
  20. Remove the EGR pipe bolts at the EGR adapter.
  21. Reposition the EGR pipe.
  22. Remove and discard the EGR valve pipe gasket.

    23. Object Number: 470770 Size: SH
  23. Remove the fuel pressure regulator vacuum hose.

    24. Object Number: 470774 Size: SH
  24. If replacing the intake manifold, remove the fuel rail studs.
  25. Remove the fuel rail.

    26. Object Number: 470775 Size: SH
  26. Remove the intake manifold bolts.

    27. Important: Do not attempt to loosen the manifold by prying under the gasket surface with any tool.

  27. Remove the intake manifold.

    28. Object Number: 470779 Size: SH

    Important: The intake manifold gaskets are not reusable.

  28. Remove and discard the intake manifold side gaskets.

    29. Object Number: 470783 Size: SH
  29. Remove and discard the intake manifold end seals.

    30. Object Number: 470786 Size: SH

    Important: The splash shield is secured using a snap-in fit. Do not distort the splash shield. The splash shield is reusable.

  30. Remove the splash shield.
  31. If replacing the intake manifold, refer to Intake Manifold Disassemble in Engine Mechanical - 8.1L Unit Repair.
  32. Clean and inspect the intake manifold. Refer to Intake Manifold Cleaning and Inspection in Engine Mechanical - 8.1L Unit Repair.

Installation Procedure

    Object Number: 470786 Size: SH
  1. If replacing the intake manifold, refer to Intake Manifold Assemble in Engine Mechanical - 8.1L Unit Repair.
  2. Install the splash shield.

    3. Object Number: 413867 Size: SH
  3. Ensure the splash shield (2) snap fits between the cylinder heads (1).

    4. Object Number: 470783 Size: SH
  4. Install NEW intake manifold end seals.

    5. Object Number: 470779 Size: SH
  5. Install NEW intake manifold side gaskets onto the cylinder heads.

    6. Object Number: 470778 Size: SH
  6. Ensure the intake manifold gasket tabs align with the hole in the head gasket.
  7. Ensure the intake manifold gasket tabs align with the slot in the intake manifold end seals.

    8. Object Number: 470775 Size: SH
  8. Install the intake manifold gaskets to the cylinder head with THIS SIDE UP stamped facing up.
  9. Install the intake manifold.

    10. Object Number: 640010 Size: SH
  10. Apply threadlock, GM U.S. P/N 12345382, Canada P/N 10953489, or equivalent to a minimum of eight threads of the intake manifold bolts.
  11. Install the intake manifold bolts.

    12. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  12. Tighten the intake manifold bolts in sequence shown, using four passes.

    13. Tighten

    1. Tighten the intake manifold bolts to 5 N·m (44 lb in) on the first pass.
    2. Tighten the intake manifold bolts to 5 N·m (44 lb in) on the second pass.

      3. Inspect the intake manifold joints for signs of intake manifold shifting. Correct as required.

    3. Tighten the intake manifold bolts to 10 N·m (89 lb in) on the third pass.
    4. Tighten the intake manifold bolts to 12 N·m (106 lb in) on the final pass.

    Object Number: 470774 Size: SH

    Important: Lubricate the fuel injector O-ring seals with clean engine oil and install onto the spray tip of each injector.

  13. If replacing the intake manifold, install the fuel rail.
  14. Install the fuel rail studs.

    15. Tighten
    Tighten the fuel rail studs to 12 N·m (106 lb in).


    Object Number: 470770 Size: SH
  15. Install the fuel pressure regulator vacuum hose.

    16. Object Number: 635635 Size: SH
  16. Install a NEW EGR valve pipe gasket.
  17. Position the EGR pipe.
  18. Install the EGR pipe bolts at the EGR adapter.

    19. Tighten
    Tighten the EGR pipe bolts to 30 N·m (22 lb ft).


    Object Number: 750530 Size: SH
  19. Connect the EGR valve electrical connector (1).

    20. Object Number: 750614 Size: SH
  20. Install the bypass valve vacuum hose (1) to the intake manifold.

    21. Object Number: 750525 Size: SH
  21. Position the engine harness over the engine compartment.
  22. Connect the following electrical connectors:
    23. • Generator (1)
    • Injector harness (2)
    • Ignition coil harness (3)
    • TP sensor (4)
    • ETC (5)
    • Purge valve solenoid (6)
  23. Install the CPA retainer at the ignition coil harness.
  24. Install the engine harness bolt and studs

    25. Tighten

        • Tighten the engine harness bolt to 5 N·m (44 lb in).
        • Tighten the engine harness stud to 10 N·m (89 lb in).

    Object Number: 750529 Size: SH
  25. Connect the following electrical connectors:
    26. • MAP sensor (1)
    • Ignition coil harness (2)
    • ECT sensor (3)
  26. Install the CPA retainer at the ignition coil harness.

    27. Object Number: 750582 Size: SH
  27. Position engine harness branch over the top of engine.
  28. Connect the following electrical connectors:
    29. • Pressure cycling switch (1)
    • Surge tank switch (2)
    • MAF sensor (3)
  29. Connect the engine harness clip to the wheelhouse splash shield.
  30. Connect the engine harness clips to the studs on the front of dash.

    31. Object Number: 665445 Size: SH
  31. Connect the fuel feed and return pipes.
  32. Install the sight shield bracket (1) and nuts.

    33. Tighten
    Tighten the sight shield bracket nuts to 5 N·m (44 lb in).

  33. Install the sight shield to the bracket (1).
  34. Tighten the intake manifold sight shield bolt (3).

    35. Tighten
    Tighten the intake manifold sight shield bolt to 10 N·m (89 lb in).


    Object Number: 700979 Size: SH
  35. Install the air cleaner outlet duct.
  36. Tighten the clamps at the throttle body and air cleaner.

    37. Tighten
    Tighten the air cleaner outlet duct clamp to 4 N·m (35 lb in).