GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2003 🢒 Seville 🢒 Engine 🢒 Engine Exhaust 🢒 Intake Manifold Replacement

Removal Procedure

    Object Number: 475295 Size: SH
  1. Remove the 2 nuts (2) from the intake manifold sight shield (1).
  2. Remove the sight shield (1) from the engine.

    3. Object Number: 490594 Size: SH
  3. Disconnect the coil module connectors (1) from the coil modules (2) located in the camshaft covers (3).

    4. Object Number: 777364 Size: SH
  4. Disconnect the PCV dirty air tube (2) from the camshaft cover.

    5. Object Number: 490598 Size: SH
  5. Disconnect the PCV fresh air tube (1) from the camshaft cover.

    6. Object Number: 490599 Size: SH
  6. Disconnect the fuel regulator vacuum tube (1).
  7. Disconnect the vacuum tubes (2) from the AIR solenoid.
  8. Disconnect the fuel inlet and return quick-connect fittings (2) at the fuel rail. Refer to Metal Collar Quick Connect Fitting Service or Plastic Collar Quick Connect Fitting Service in Engine Controls-4.6 L.

    9. Object Number: 490600 Size: SH
  9. Disconnect the fuel rail bracket retaining nut (1) at the rear lift bracket.

    10. Object Number: 490601 Size: SH
  10. Remove the 2 pushnuts securing the engine coolant heater wire (1) and position aside (if equipped).

    11. Object Number: 490817 Size: SH
  11. Disconnect the 8 electrical connectors (1) from the 8 fuel injectors (2).

    12. Object Number: 490819 Size: SH
  12. Remove the 4 bolts (1) attaching the fuel rail (2) to the intake manifold (3).

    13. Object Number: 522658 Size: SH
  13. Lift the entire fuel rail and injector assembly from the intake manifold.

    14. Object Number: 522666 Size: SH
  14. Loosen the plenum duct clamp (1) at the rear of the intake manifold.

    15. Object Number: 490821 Size: SH
  15. Remove 10 bolts attaching the intake manifold (1) to the cylinder heads.

    16. Object Number: 490825 Size: SH
  16. Remove the intake manifold (1) by using an upward lifting motion at the front of the manifold assembly.
  17. Clean and inspect the intake manifold. Refer to Intake Manifold Cleaning and Inspection in Engine Mechanical-4.6L Unit Repair.

Installation Procedure

    Object Number: 490830 Size: SH
  1. Lightly grease the inside edge of the rubber plenum duct.

    2. Object Number: 490825 Size: SH
  2. Clean any debris from the cylinder head or intake manifold.
  3. Install the new gaskets to the intake manifold.

    4. Important: Ensure the PCV valve hose is firmly connected to the fitting at the front of the intake manifold, prior to installation.

  4. Place the intake manifold in position by completing the following:
    5. 4.1. Position the rear of the intake manifold (1) into the plenum duct (2).
    4.2. Position the front of the intake manifold (1) downward on to the cylinders heads.

    Object Number: 490821 Size: SH
  5. Loosely install the 10 bolts attaching the intake manifold (1) to the cylinder heads.

    6. Object Number: 797947 Size: SH

    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.

  6. Tighten the intake manifold bolts in sequence (1-10).

    7. Tighten
    Tighten the intake manifold bolts to 10 N·m (89 lb in).


    Object Number: 522666 Size: SH
  7. Ensure that the plenum duct is fully attached to the rear of the intake manifold.

    8. Tighten
    Tighten the plenum duct clamp (1) to 2.25 N·m (20 lb in).


    Object Number: 522658 Size: SH
  8. Lubricate the intake manifold fuel injector bores with light mineral oil GM P/N 9981704, clean engine oil, or equivalent.

    9. Important: DO NOT force the injectors into position.

  9. Install the entire fuel rail and injector assembly into the intake manifold by pressing the fuel rail and injector simultaneously into the correct position.

    10. Object Number: 490819 Size: SH
  10. Install the 4 bolts (1) attaching the fuel rail (2) to the intake manifold (3).

    11. Tighten
    Tighten the fuel rail bolts to 10 N·m (89 lb in).


    Object Number: 490817 Size: SH
  11. Connect the 8 electrical connectors (1) to the 8 fuel injectors (2).

    12. Object Number: 490601 Size: SH
  12. Position the engine coolant heater wire (1) on to the fuel rail studs (if equipped).
  13. Install the 2 pushnuts.

    14. Object Number: 490600 Size: SH
  14. Install the fuel rail bracket retaining nut (1) to the rear lift bracket.

    15. Tighten
    Tighten the fuel rail bracket retaining nut (1) to 10 N·m (89 lb in).

  15. Install the quick connect fittings to the fuel rail. Refer to Metal Collar Quick Connect Fitting Service or Plastic Collar Quick Connect Fitting Service in Engine Controls-4.6 L.

    16. Object Number: 490599 Size: SH
  16. Connect the vacuum tubes (2) to the AIR solenoid.
  17. Connect the fuel regulator vacuum tube (1).

    18. Object Number: 490598 Size: SH
  18. Connect the PCV fresh air tube (1) to the camshaft cover.

    19. Object Number: 777364 Size: SH
  19. Connect the PCV dirty air tube (2) to the camshaft cover.

    20. Object Number: 490594 Size: SH
  20. Connect the coil module connectors (1) to the coil modules (2) located in the camshaft covers (3).
  21. To clean, turn the ignition switch to the ON position for 2 seconds, then turn to the OFF position for 10 seconds. Again turn to the ON position and check for fuel leaks.

    22. Object Number: 475295 Size: SH
  22. Position the intake manifold sight shield (1) to the engine.
  23. Install the 2 intake manifold sight shield nuts (2).

    24. Tighten
    Tighten the nuts to 3 N·m (27 lb in).