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Home >> Buick >> 2004 >> Century Limited >> Repair and Diagnosis >> External Pages >> Different car >> Section 87 (Engine Mechanical - 3.8L) >> Repair Instructions >> On-Vehicle Repair Instructions >> Intake Manifold Replacement - Upper >> Removal Procedure

Removal Procedure

WARNING: This page is about a different car, the 2004 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
  1. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure in Engine Electrical.
  2. Remove the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement (L36)  or Fuel Injector Sight Shield Replacement (L67) .
  3. Remove the air cleaner intake duct. Refer to Air Cleaner Intake Duct Replacement in Engine Controls-3.8L.
  4. Drain the cooling system. Refer to Draining and Filling Cooling System in Engine Cooling.
  5. Remove the right spark plug wires from the ignition control module and reposition. Refer to Spark Plug Wire Replacement in Engine Controls - 3.8L.
  6. Relieve the fuel pressure. Refer to Fuel Pressure Relief Procedure in Engine Controls - 3.8L.
  7. Remove the fuel rail assembly. Refer to Fuel Rail Assembly Replacement (L36) or Fuel Rail Assembly Replacement (L67) in Engine Controls - 3.8L.
  8. Remove the brake booster hose from the vacuum source manifold.
    9. Fig 1: Installing EGR Valve Wiring Harness Heat Shield
    GM190554Courtesy of GENERAL MOTORS CORP.
  9. Remove the exhaust gas recirculation (EGR) valve wiring harness heat shield nut, bolt and the EGR heat shield.
    10. Fig 2: Throttle Body Support Bracket
    GM153567Courtesy of GENERAL MOTORS CORP.
  10. Remove the throttle body support bracket upper bolt.
  11. Disconnect the electrical connectors from the following:
    • EVAP purge solenoid
    • Throttle position (T/P) sensor
    • Idle air control (IAC) valve
    • Manifold absolute pressure (MAP) sensor
    • Mass air flow (MAF) sensor
  12. Remove the EVAP purge solenoid vacuum line from the throttle body.
  13. Remove the accelerator and the cruise control cables with the bracket from the throttle body. Refer to Accelerator Controls Cable Bracket Replacement in Engine Controls - 3.8L.
    14. Fig 3: Upper Intake Manifold, Bolts And Stud
    GM153570Courtesy of GENERAL MOTORS CORP.
  14. Remove the upper intake manifold bolts and stud.
  15. Clean the upper intake manifold bolt threads.
  16. Remove the upper intake manifold by lifting the back of the intake and sliding the manifold forward from the throttle body support bracket.
    17. Fig 4: Upper-To-Lower Intake Manifold Carrier Gasket
    GM405818Courtesy of GENERAL MOTORS CORP.
  17. Remove the upper-to-lower intake manifold carrier gasket from the upper intake manifold.
  18. If the upper intake manifold is being replaced, remove the following:
    • Throttle body
    • Manifold absolute pressure (MAP) sensor
    • Positive crankcase ventilation (PCV) valve
    • Vacuum source manifold
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