GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2007 🢒 Lucerne 🢒 Engine 🢒 Engine Mechanical - 3.8L 🢒 Upper Intake Manifold Replacement

Removal Procedure

    Object Number: 1686286 Size: SH
  1. Remove the air cleaner outlet duct.
  2. Remove the fuel rail assembly. Refer to Fuel Injection Fuel Rail Assembly Replacement .
  3. Remove the brake booster vacuum hose from the upper intake manifold fitting.

    4. Object Number: 1686302 Size: SH
  4. Disconnect the evaporative emission (EVAP) pipe quick connect fitting (2) from the purge solenoid. Refer to Plastic Collar Quick Connect Fitting Service .

    5. Object Number: 1686291 Size: SH
  5. Remove the engine wiring harness heat shield nut and bolt.
  6. Remove the engine wiring harness heat shield.

    7. Object Number: 1686292 Size: SH
  7. Remove the upper intake manifold bolts and studs.
  8. Remove the upper intake manifold.

    9. Object Number: 1686294 Size: SH
  9. If replacing the intake manifold perform the following steps, otherwise proceed to step 10 in the installation procedure.
  10. Disengage the retainers and remove the manifold absolute pressure (MAP) sensor.

    11. Object Number: 1686295 Size: SH
  11. Remove the EVAP purge solenoid bolt and solenoid.

    12. Object Number: 1686343 Size: SH
  12. Loosen the throttle body upper bolts.
  13. Remove the throttle body lower nuts.
  14. Remove the throttle body.

    15. Object Number: 1686345 Size: SH
  15. Squeeze the sides of the vacuum fitting in order to disengage the retainers and remove the vacuum fitting.
  16. Remove and discard the O-ring seal.

    17. Object Number: 1686293 Size: SH
  17. Remove the intake manifold gasket carrier from the upper intake manifold.

Installation Procedure

    Object Number: 1686293 Size: SH
  1. If replacing the intake manifold perform the following steps, otherwise proceed to 10.
  2. Install a the intake manifold gasket carrier to the upper intake manifold.

    3. Object Number: 1686345 Size: SH
  3. Install a NEW vacuum fitting O-ring seal.
  4. Squeeze the sides of the vacuum fitting in order to install the vacuum fitting.

    5. Object Number: 1686343 Size: SH
  5. Install the throttle body.
  6. Tighten the throttle body upper bolts.

    7. Notice: Refer to Fastener Notice in the Preface section.

  7. Install the throttle body lower nuts.

    8. Tighten
    Tighten the bolts/nuts to 10 N·m (89 lb in).


    Object Number: 1686295 Size: SH
  8. Install the EVAP purge solenoid and bolt.

    9. Tighten
    Tighten the bolt to 10 N·m (89 lb in).


    Object Number: 1686294 Size: SH
  9. Install the MAP sensor.

    10. Object Number: 1686292 Size: SH
  10. Install the upper intake manifold.
  11. Install the upper intake manifold bolts and studs.

    12. Object Number: 49828 Size: SH
  12. Tighten the upper intake manifold bolts and studs in the sequence shown.

    13. Tighten
    Tighten the bolts/studs to 10 N·m (89 lb in).


    Object Number: 1686291 Size: SH
  13. Install the engine wiring harness heat shield.
  14. Install the engine wiring harness heat shield nut and bolt.

    15. Tighten
    Tighten the bolt/nut to 10 N·m (89 lb in).


    Object Number: 1686302 Size: SH
  15. Connect the EVAP pipe quick connect fitting (2) to the purge solenoid. Refer to Plastic Collar Quick Connect Fitting Service .

    16. Object Number: 1686286 Size: SH
  16. Install the brake booster vacuum hose to the upper intake manifold fitting.
  17. Install the fuel rail assembly. Refer to Fuel Injection Fuel Rail Assembly Replacement .
  18. Install the air cleaner outlet duct.