AutoZone 1968 MG MG Midget 1.3L 1BL 2 Carb OHV 4cyl | Repair Guides | Engine And Engine Overhaul | Engine Mechanical | Intake Manifold | AutoZone.com

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    GM Century/Lumina/Grand Prix/Intrigue 1997-2000

    Intake Manifold

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    REMOVAL & INSTALLATION



    3.1L Engine

    NOTE
    The 3.1L engine uses a two-piece intake manifold consisting of an upper air plenum which mounts the throttle body and a lower intake manifold assembly which houses the fuel injectors.


    WARNING
    This engine uses a sequential multiport fuel injection system. The fuel injector electrical connectors MUST connected to their proper injectors or engine performance will be seriously affected. Identify and tag all injector connectors that are removed. This is most important.

    UPPER INTAKE MANIFOLD (PLENUM)


    Click image to see an enlarged view

    Fig. Unfasten the retainers, then remove the upper manifold-3.1L engine

    1. Disconnect the negative battery cable.
    2.  
    3. Remove the air cleaner duct.
    4.  
    5. Drain the cooling system into a suitable container.
    6.  
    7. Remove the accelerator control and cruise control cables with the bracket from the throttle body.
    8.  
    9. Detach the wiring harness connectors from the throttle body.
    10.  
    11. Remove the thermostat bypass pipe coolant hoses from the throttle body.
    12.  
    13. Tag for identification and remove the vacuum hoses from the throttle body and the upper intake manifold.
    14.  
    15. Tag and disconnect the front spark plug wires.
    16.  
    17. Remove the ignition coil bracket with the coils, the purge solenoid and the vacuum canister solenoid.
    18.  
    19. Remove the Manifold Absolute Pressure (MAP) sensor and bracket.
    20.  
    21. Remove the alternator rear brace.
    22.  
    23. Remove the Exhaust Gas Recirculation (EGR) valve.
    24.  
    25. Remove the upper intake manifold bolts and nuts and lift the upper intake manifold off the engine. Remove the gaskets. The throttle body can be removed, if necessary. Otherwise, do not disturb the throttle body assembly. Cover the lower intake manifold with a clean cloth to keep debris out of the intake ports.
    26.  

    To install:

    1. Clean all parts well with a degreaser, especially all sealing surfaces.
    2.  
    3. Install new upper intake manifold gaskets
    4.  
    5. Install the upper intake manifold and the bolts and nuts. Torque all fasteners to 18 ft. lbs. (25 Nm).
    6.  
    7. Install the remaining components in the reverse order of the removal process.
    8.  

    LOWER INTAKE MANIFOLD


    Click image to see an enlarged view

    Fig. Exploded view of the lower intake manifold arrangement-3.1L engine

    1. Disconnect the negative battery cable.
    2.  
    3. Remove the upper intake manifold as outlined earlier.
    4.  
    5. Remove both valve rocker arm covers as outlined in this section.
    6.  
    7. Relive the fuel system pressure. Please see .
    8.  
    9. Disconnect the fuel injector feed and return pipes from the fuel rail. Please see .
    10.  
    11. Without disconnect the fluid lines, remove the power steering pump from the front engine cover and reposition aside.
    12.  
    13. Disconnect the heater inlet pipe from the lower intake manifold.
    14.  
    15. Disconnect the upper radiator hose from the engine.
    16.  
    17. Remove the lower intake manifold bolts and carefully lift the manifold from the engine. Discard the gaskets.
    18.  

    To install:

    1. Clean all parts well with degreaser, especially the gasket seal surfaces on the cylinder heads and the engine block. Remove all the loose RTV sealer.
    2.  
    3. Apply a bead of RTV sealant approximately 1 / 4 inch in diameter on each ridge where the front and rear of the lower intake manifold contacts the engine block. Install new lower intake manifold gaskets and carefully lower the lower intake manifold into place.
    4.  
    5. Bolt installation requires some care. Note that some bolts are "vertical" when installed, others are "diagonal" when installed. Apply a thin, even coat of sealer GM #12345382 or equivalent, to all of the bolt threads. Hand tighten the vertical bolts first, then tighten the diagonal bolts. Note that an oil leak will result if the vertical bolts are not tightened before the diagonal bolts. Now torque the vertical bolts to 115 inch lbs. (13 Nm), followed by the diagonal bolts, also to 115 inch lbs. (13 Nm).
    6.  
    7. Install the remaining components in the reverse order of the removal process.
    8.  

    3.4L (VIN X) Engine

    NOTE
    The 3.4L (VIN X) engine uses a two-piece intake manifold consisting of an upper air plenum which mounts the throttle body and a lower intake manifold assembly which houses the fuel injectors.

    UPPER INTAKE MANIFOLD (PLENUM)


    Click image to see an enlarged view

    Fig. Unfasten the retainers, then remove the upper manifold-1997 3.4L (VIN X) engine shown

    1. Disconnect the negative battery cable.
    2.  
    3. Remove the air cleaner duct.
    4.  
    5. Drain the cooling system into a suitable container.
    6.  
    7. Disconnect the throttle and cruise control cables from the throttle body.
    8.  
    9. Remove the cosmetic/acoustic engine cover.
    10.  
    11. Remove the evaporative emission canister purge solenoid bracket bolts and remove the solenoid.
    12.  
    13. Tag for identification, then disconnect the spark plug wires. Please see for more information.
    14.  
    15. Remove the ignition control module mounting bolts and remove the module with the coil assemblies. Remove the bolts and then remove the ignition module mounting bracket.
    16.  
    17. Tag for identification, then disconnect all vacuum lines from the upper intake manifold.
    18.  
    19. Remove the upper intake manifold bolts and carefully lift the manifold from the engine. Discard the gaskets.
    20.  

    To install:

    1. Clean all parts well with degreaser, especially the gasket seal surfaces on both the upper manifold and the lower manifold.
    2.  
    3. Install a new upper manifold gasket, carefully set the manifold into place and then install the bolts. Torque the bolts evenly to 19 ft. lbs. (26 Nm).
    4.  
    5. Install the remaining components in the reverse order of the removal process.
    6.  

    LOWER INTAKE MANIFOLD


    Click image to see an enlarged view

    Fig. Lower intake manifold arrangement-1997 3.4L (VIN X) engine shown

    1. Remove the upper intake manifold using the earlier procedure, including draining the cooling system.
    2.  
    3. Remove the fuel rail. Please see .
    4.  
    5. Disconnect the radiator hose from the thermostat housing.
    6.  
    7. Detach the electrical connector at the temperature sensor.
    8.  
    9. Remove the heater pipe nut at the throttle body.
    10.  


    NOTE
    Installing the intake manifold will take some care. As the bolts are removed, make note of their original locations and hardware (washers, etc.) so they can be returned to their original locations.

    1. Remove the lower intake manifold mounting bolts and carefully lift off the lower manifold. Discard the gaskets.
    2.  

    To install:

    1. Clean all parts well with degreaser, especially the gasket seal surfaces on the cylinder heads and the engine block.
    2.  
    3. Install new lower intake manifold gaskets and carefully lower the lower intake manifold into place.
    4.  
    5. Bolt installation requires some care. Use the following procedure:
      1. Install two spare 8mm x 1.25 x 50mm bolts with washers to the vertical holes in the intake manifold. Tighten gently to 62 inch lbs. (7 Nm). The reason for this is, that installing the bolts in the vertical holes of the manifold will align the intake bolt grommet bores with the threaded holes in the cylinder heads. This will minimize the possibility of cross-threading and damage to the grommets resulting in a leak at the intake manifold gaskets.
      2.  
      3. Install the lower intake mounting bolts. Insert the rubber isolators fully into the manifold mounting flange before tightening any fasteners.
      4.  
      5. Draw the lower intake manifold in place by tightening the bolts gradually, starting with the middle bolts and working in a circular pattern. Do not tighten one side or one end fully.
      6.  
      7. Final torque the bolts to 116 inch lbs. (13 Nm).
      8.  
      9. Remove the two bolts in the vertical holes of the intake manifold.
      10.  

    6.  
    7. Install the remaining components in the reverse order of the removal process. Use care when installing the fuel rail with the fuel injectors. Please see .
    8.  

    3.4L (VIN E) Engine

    NOTE
    The 3.4L VIN E engine uses a two-piece intake manifold consisting of an upper air plenum which mounts the throttle body and a lower intake manifold assembly which houses the fuel injectors.


    WARNING
    This engine uses a sequential multiport fuel injection system. The fuel injector electrical connectors MUST connected to their proper injectors or engine performance will be seriously affected. Identify and tag all injector connectors that are removed. This is most important.

    UPPER INTAKE MANIFOLD (PLENUM)


    Click image to see an enlarged view

    Fig. Unfasten the retainers, then remove the upper manifold-3.4L (VIN E) engine shown

    1. Disconnect the negative battery cable.
    2.  
    3. Tag for identification and disconnect all vacuum lines that connect to the upper intake manifold.
    4.  
    5. Detach the wiring harness connection from the Intake Air Temperature (IAT) sensor in the throttle body air inlet duct. Then remove the throttle body air inlet duct.
    6.  
    7. Drain the cooling system into a suitable container.
    8.  
    9. Remove the accelerator control and cruise control cables, with the bracket, from the throttle body.
    10.  
    11. Tag for identification and detach the wiring harness connectors from the Throttle Position (TP) sensor and the Idle Air Control (IAC) valve.
    12.  
    13. Disconnect the wiring harness attachment clips from the Camshaft Position (CMP) sensor harness and the left side spark plug wire harness.
    14.  
    15. Disconnect the thermostat bypass pipe coolant hoses from the throttle body.
    16.  
    17. Remove the alternator rear brace and the alternator bracket.
    18.  
    19. Remove the Manifold Absolute Pressure (MAP) sensor and Exhaust Gas Recirculation (EGR) valve.
    20.  
    21. Tag for identification and remove the spark plug wires.
    22.  
    23. Remove the ignition control module. Please see for more information.
    24.  
    25. Remove the upper intake manifold bolts and carefully remove the upper intake manifold. Discard the gaskets.
    26.  

    To install:

    1. Clean all parts well with degreaser, especially the gasket seal surfaces on both the upper manifold and the lower manifold.
    2.  
    3. Install a new upper manifold gasket, carefully set the manifold into place and then install the bolts. Torque the bolts evenly to 19 ft. lbs. (26 Nm), starting from the center and working outward.
    4.  
    5. Install the remaining components in the reverse order of the removal process.
    6.  

    LOWER INTAKE MANIFOLD
    1. Disconnect the negative battery cable.
    2.  
    3. Remove the upper intake manifold assembly using the procedure in this section.
    4.  
    5. Remove the valve rocker arm covers using the procedures in this section.
    6.  
    7. Detach the Engine Coolant Temperature (ECT) wiring harness from the sensor in the thermostat housing.
    8.  
    9. Tag for identification and detach the fuel injector and Manifold Absolute Pressure (MAP) sensor wiring harness connectors.
    10.  
    11. Remove the fuel pipe clip bolt, remove the clip, then disconnect the fuel feed pipe from the fuel rail. Also disconnect the fuel return pipe from the fuel rail. Please see .
    12.  
    13. Remove the fuel injector rail. Please see .
    14.  
    15. Without disconnecting the fluid lines, remove the power steering pump from the front engine cover and reposition aside.
    16.  
    17. Disconnect the heater inlet pipe from lower intake manifold and reposition aside.
    18.  
    19. Disconnect the radiator inlet hose from the engine. Also disconnect the small thermostat bypass hose that runs between the thermostat pipe and the lower intake manifold pipe.
    20.  
    21. Remove the lower intake manifold bolts and carefully lift the lower intake manifold from the engine.
    22.  
    23. Remove the rocker arms and pushrods as outlined in this section.
    24.  
    25. Remove and discard the gaskets.
    26.  

    To install:

    1. Clean all parts well with degreaser, especially the gasket seal surfaces on the cylinder heads and the engine block. Remove all the loose RTV sealer.
    2.  
    3. Install the lower intake manifold gaskets.
    4.  
    5. Install the valve rocker arms and pushrods, following the procedure in this section.
    6.  
    7. Apply a bead of RTV sealant approximately 1 / 4 inch in diameter on each ridge where the front and rear of the lower intake manifold contacts the engine block. Install new lower intake manifold gaskets and carefully lower the lower intake manifold into place.
    8.  
    9. Bolt installation requires some care. Note that some bolts are "vertical" when installed, others are "diagonal" when installed. Apply a thin, even coat of sealer GM #12345382 or equivalent, to all of the bolt threads. Hand tighten the vertical bolts first, then tighten the diagonal bolts. Note that an oil leak will result if the vertical bolts are not tightened before the diagonal bolts. Now torque the vertical bolts to 115 inch lbs. (13 Nm), followed by the diagonal bolts, also to 115 inch lbs. (13 Nm).
    10.  
    11. Install the remaining components in the reverse order of the removal process.
    12.  

    3.5L Engine

    NOTE
    It is important to correctly identify the source of an oil leak. A power steering fluid leak or spillage can travel across the valley area of the engine and run out the weep hole, which is located at the back of the block. Failure to correctly identify the source of an oil leak can lead to the incorrect or unnecessary replacement of components.



    Click image to see an enlarged view

    Fig. Intake manifold arrangement-3.5L (VIN H) engine

    1. Disconnect the negative battery cable.
    2.  
    3. Carefully remove the throttle body air inlet duct from the throttle body.
    4.  
    5. Partially drain the cooling system into a suitable container.
    6.  
    7. Remove the cosmetic/acoustic engine cover.
    8.  
    9. Disconnect the accelerator and cruise control cables from the bracket.
    10.  
    11. Disconnect the coolant hoses to the throttle body.
    12.  
    13. Relieve the fuel system pressure and disconnect the fuel rail quick-connect fittings. Please see .
    14.  
    15. Disconnect the following vacuum lines from the intake manifold:
      1. The vapor line from the EVAP canister purge solenoid.
      2.  
      3. The power brake booster vacuum hose.
      4.  
      5. The air conditioning vacuum hose.
      6.  

    16.  
    17. Disconnect the surge tank inlet pipe from the fuel rail.
    18.  
    19. Tag for identification then detach the fuel injector wiring harness connectors.
    20.  
    21. Tag for identification then detach the Throttle Position (TP) sensor, Idle Air Control (IAC) valve, EVAP purge solenoid and Manifold Absolute Pressure (MAP) sensor wiring harness connectors.
    22.  
    23. Remove the engine wiring harness channel bolts from the camshaft covers and set the harness and channel assemblies.
    24.  
    25. Disconnect the fuel pressure regulator vacuum tube from the regulator and the throttle body.
    26.  
    27. Disconnect and remove the PCV valve and both feed tubes from the camshaft covers and intake manifold.
    28.  
    29. Remove the EGR valve outlet pipe retaining bolts from the intake manifold and the water crossover, then remove the EGR outlet pipe.
    30.  
    31. Disconnect the four fuel rail snap-lock retainers by pushing toward the camshaft covers and lifting. Remove the fuel rail and fuel injectors as an assembly by lifting straight up. Store is a clean, safe place. Since the rail still contains gasoline, keep it away from any heat sources.
    32.  
    33. Remove the throttle body heater hose insulator plate.
    34.  
    35. Remove the intake manifold bolts.
    36.  
    37. Using pliers to loosen the clamp, disconnect the throttle body coolant hoses from the water crossover feed tube.
    38.  
    39. Remove the intake manifold assembly.
    40.  

    To install:

    1. Clean all parts well with degreaser, especially the gasket seal surfaces on the cylinder heads and the engine block.
    2.  
    3. Install the intake manifold gaskets. Carefully lower the intake manifold into place.
    4.  
    5. Before bolting the manifold down, connect the throttle body heater hose to the water crossover feed tube. Install the hose clamp.
    6.  
    7. Hand tighten the bolts first. Then torque the bolts to 62 inch lbs. (7 Nm). Tighten the bolts in a circular pattern starting from the center and working outward.
    8.  
    9. Install the remaining components in the reverse order of the removal process, observing the following.
      1. Inspect the fuel injector O-rings or misalignment or damage. Replace the O-rings if necessary. Install the fuel rail and fuel injectors by aligning the fuel injectors with their respective ports and pressing the four fuel rail snap-lock connectors into the intake manifold until they lock in place. DO NOT apply excessive pressure to the fuel rail. The need for excessive pressure may be caused by misalignment of a fuel injector and could cause damage to the seal or even the manifold.
      2.  
      3. GM recommends that a new replacement EGR outlet pipe be installed.
      4.  
      5. Use care to make sure all vacuum hoses are properly installed.
      6.  
      7. Take care to make sure the fuel injector harness connectors are properly installed. This engine uses sequential fuel injectors and the harness connectors MUST be attached to the proper injector.
      8.  

    10.  

    3.8L Engine

    NOTE
    The 3.8L (VIN K) non-supercharged engine uses a two-piece intake manifold consisting of an upper air plenum which mounts the throttle body and a lower intake manifold assembly which houses the fuel injectors. The 3.8L (VIN 1) supercharged engine uses a similar lower intake manifold. The supercharger serves as the upper manifold.

    UPPER INTAKE MANIFOLD (PLENUM)
    1. Disconnect the negative battery cable.
    2.  
    3. On 3.8L (VIN 1) engines, remove the supercharger assembly. Please see the procedure in this section.
    4.  
    5. Tag for identification, then remove the right side spark plug wires.
    6.  
    7. Disconnect the ignition wires from the fuel rail.
    8.  
    9. Remove the fuel rail. Please see .
    10.  
    11. Remove the cable bracket from the intake manifold.
    12.  
    13. Remove the throttle body.
    14.  


    NOTE
    Two bolts which fasten the lower intake manifold to the cylinder head are accessible are accessible only after the upper intake manifold is removed. These bolts are located in the right front and left rear corners of the lower intake manifold.

    1. Remove the upper intake manifold bolts and carefully lift the upper intake manifold from the engine.
    2.  



    Click image to see an enlarged view

    Fig. Upper intake manifold and bolt torque sequence-3.8L (VIN K) engine

    To install:

    1. Clean all parts well with degreaser, especially the gasket seal surfaces on the upper and lower manifold pieces.
    2.  
    3. Install new gaskets to the cylinder heads and new seals to the engine block. Carefully lower the manifold into place. Make sure to install the two hidden bolts in the lower intake manifold. Hand start all bolts, then torque evenly to 89 inch lbs. (10 Nm). Follow the torque sequence, starting in the center, then working outwards in a circle.
    4.  
    5. Install the remaining components in the reverse order of the removal process.
    6.  

    LOWER INTAKE MANIFOLD

    NOTE
    Two bolts which fasten the lower intake manifold to the cylinder head are accessible only after the upper intake manifold is removed. These bolts are located in the right front and left rear corners of the lower intake manifold. Remove the upper intake manifold to service the lower intake.

    The 3.8L (VIN 1) supercharged engine uses a manifold similar to the 3.8L (VIN K), but the supercharger serves as the upper manifold.

    1. Disconnect the negative battery cable.
    2.  
    3. On 3.8L (VIN 1) engines, remove the supercharger assembly. Please see the procedure in this section.
    4.  
    5. Remove the upper intake manifold using the procedure above.
    6.  
    7. Remove the EGR outlet pipe from the intake manifold.
    8.  
    9. Detach the engine coolant temperature sensor wiring harness from the sensor.
    10.  
    11. Remove the lower intake manifold bolts and carefully lift off the manifold.
    12.  

    To install:



    Click image to see an enlarged view

    Fig. Lower intake manifold bolt torque sequence-3.8L (VIN K) engine

    1. Clean all parts well with degreaser, especially the gasket seal surfaces on the upper and lower manifold pieces and between the lower manifold and the cylinder heads..
    2.  
    3. Install new gaskets to the cylinder heads and new seals to the engine block. Carefully lower the manifold into place. Apply thread-locking compound to the bolt threads. Make sure to install the two hidden bolts in the lower intake manifold. Hand start all bolts, then torque evenly to 11 ft. lbs. (15 Nm). Follow the toque sequence, starting in the center, then working outwards in a circle.
    4.  
    5. Install the remaining components in the reverse order of the removal process.
    6.  

     
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