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

Removal Procedure

    Object Number: 910975 Size: SH
  1. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection .
  2. Remove the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement .
  3. Remove the air cleaner intake duct. Refer to Air Cleaner Inlet Duct Replacement .
  4. Drain the cooling system. Refer to Cooling System Draining and Filling .
  5. Remove the right spark plug wires from the ignition control module and the upper intake manifold and reposition the wires. Refer to Spark Plug Wire Replacement .
  6. Relieve the fuel pressure. Refer to Fuel Pressure Relief .
  7. Remove the brake booster hose (1) from the vacuum source manifold (2).
  8. Disconnect the electrical connectors from the following:
    9. • Electronic throttle control (ETC)
    • Evaporative emission (EVAP) purge solenoid
    • Manifold absolute pressure (MAP) sensor
    • Mass air flow (MAF) sensor

    Object Number: 911071 Size: SH
  9. Remove the exhaust gas recirculation (EGR) valve wiring harness heat shield nut (1), bolt (2) and the EGR heat shield (3).
  10. Disconnect the EVAP purge solenoid pipe quick connect fitting. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .

    11. Object Number: 910936 Size: SH
  11. Remove the fuel rail assembly nuts (2).
  12. Remove the fuel rail assembly (1) with the fuel injectors (3).

    13. Object Number: 910998 Size: SH
  13. Remove the upper intake manifold bolts (1, 4) and the studs (2, 3).
  14. Clean the upper intake manifold bolt threads.
  15. Remove the upper intake manifold.

    16. Object Number: 405818 Size: SH
  16. Remove the upper-to-lower intake manifold carrier gasket from the upper intake manifold.
  17. If the upper intake manifold is being replaced, remove the following:
    18. • Throttle body
    • MAP sensor
    • Positive crankcase ventilation (PCV) valve
    • Vacuum source manifold

Installation Procedure
  1. If the manifold was replaced install the following:
    2. • Vacuum source manifold
    • PCV valve
    • MAP sensor
    • Throttle body

    Object Number: 405818 Size: SH
  2. Install the upper-to-lower intake manifold carrier gasket to the upper intake manifold.

    3. Object Number: 910998 Size: SH
  3. Carefully install the upper intake manifold (5) onto the lower intake manifold. Ensure that the alignment pins in the upper intake manifold align with the holes in the lower intake manifold.
  4. Apply threadlock compound to the threads of the bolts (1, 4) and the studs (2, 3). Refer to Adhesives, Fluids, Lubricants, and Sealers for the correct part number.

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


    Object Number: 49828 Size: SH
  5. Install the upper intake manifold bolts and the studs (1-10).

    6. Tighten
    Tighten the bolts in sequence to 10 N·m (89 lb in).


    Object Number: 910936 Size: SH
  6. Lightly coat the fuel injectors (3) with clean engine oil.

    7. Important: Ensure the fuel rail is fully seated in the lower intake manifold assembly.

  7. Install the fuel rail assembly (1) to the lower intake assembly.
  8. Install the fuel rail nuts (2).

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

  9. Connect the EVAP purge solenoid pipe quick connect fitting. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .

    10. Object Number: 911071 Size: SH
  10. Install the EGR valve wiring harness heat shield (3), the nut (1) and the bolt (2).

    11. Tighten
    Tighten the nut and the bolt to 10 N·m (89 lb in).


    Object Number: 910975 Size: SH
  11. Install the brake booster hose (1) to the vacuum source manifold (2).
  12. Connect the electrical connectors to the following:
    13. • MAF sensor
    • MAP sensor
    • EVAP purge solenoid
    • ETC
  13. Install the right spark plug wires to the ignition control module and the upper intake manifold. Refer to Spark Plug Wire Replacement .
  14. Install the air cleaner intake duct. Refer to Air Cleaner Inlet Duct Replacement .
  15. Install the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement .
  16. Fill the cooling system. Refer to Cooling System Draining and Filling .
  17. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection .
  18. Inspect for fluid or vacuum leaks.