Tuesday, April 3, 2012

How to Replace Intake Manifold on GMC, Chevrolet and Cadillac models?

This chapter Provides details for replacing Intake Manifold.
The procedure covers Following car models Listed Below:-----
Cadillac Escalade, GMC Suburban 1500 & 2500, Chevrolet Tahoe, GMC Yukon, Yukon XL 1500 & 2500 (2006-2007), Yukon Denali and Yukon Denali XL (2005-2006).GMC Sierra, Chevrolet Silverado 2006-2007.

The procedure is mentioned for 8.1L engine AND
4.8L, 5.3L, 6.0L & 6.2L Engine Models.

The procedure is as follows:-----

Intake Manifold
4.8L, 5.3L, 6.0L & 6.2L Engines

The intake manifold, throttle body, fuel injection rail, and fuel injectors may be removed as an assembly. If not servicing the individual components, remove the manifold as a complete assembly.

  1. Remove or disconnect the following: 

    Positive Crankcase Ventilation (PCV) hose and valve
    Manifold Absolute Pressure (MAP) sensor, if required
    Engine coolant air bleed clamp and hose from the throttle body
    Knock sensor connector, if required.
    Accelerator control cable bracket and bolts, if required
    Fuel rail with injectors, if required
    EVAP solenoid, bolt, and isolator
    Any additional engine harness attachment points and set aside
    Intake manifold bolts
    Intake manifold with gaskets
    Intake manifold-to-cylinder head gaskets from the manifold. Discard the intake manifold gaskets. 

    Fig. Always use new gaskets-4.8L, 5.3L, 6.0L and 6.2L engines
  2. Clean the intake manifold in solvent.
  3. Dry the intake manifold with compressed air.
  4. Inspect the intake manifold vacuum passages for debris or restrictions.
  5. Inspect for damaged or broken vacuum fittings, damaged MAP sensor mounting bore, or broken MAP sensor retaining tabs.
  6. Inspect the composite intake manifold assembly for cracks or other damage.
  7. Inspect the areas between the intake runners. Inspect all the gasket sealing surfaces for damage.
  8. Inspect the fuel injector bores for excessive scoring or damage. Inspect the intake manifold cylinder head deck for warpage.
  9. Locate a straight edge across the intake manifold cylinder head deck surface. Position the straight edge across a minimum of two runner port openings.
  10. Insert a feeler gauge between the intake manifold and the straight edge. A intake manifold with warpage in excess of 0.118 in. (3mm) over a 7.87 in. (200mm) area is warped and should be replaced.
To install:
  1. Install or connect the following:

    MAP sensor
    EVAP solenoid, bolt, and isolator. Tighten the bolt to 89 inch lbs. (10 Nm).
    NEW intake manifold-to-cylinder head gaskets
    Intake manifold
  2. Apply a 0.20 in. (5mm) band of threadlock GM P/N 12345382 or equivalent to the threads of the intake manifold bolts. 

    Intake manifold bolts. Tighten intake manifold bolts first pass in sequence to 44 inch lbs. (5 Nm). Tighten intake manifold bolts final pass in sequence to 89 inch lbs. (10 Nm). 

    Fig. Lower intake manifold bolt tightening sequence-4.8L, 5.3L, 6.0L and 6.2L engines
    PCV valve and hose
    Coolant air bleed hose and clamp onto the throttle body
    Accelerator control cable bracket and bolts. Tighten the bolts to 89 inch lbs. (10 Nm).
8.1L Engine

The intake manifold, throttle body, fuel rail and injectors can be removed as an assembly. If you do not need to service these components individually, remove the manifold as a complete assembly.

  1. Relieve the fuel system pressure and drain the cooling system.
  2. Remove or disconnect the following:

    Air cleaner outlet duct
    Intake manifold sight shield
    Fuel feed and return pipes
    Engine harness clips from the studs on the front of the dash
    Engine harness clip from the wheelhouse splash shield
    Pressure cycling switch, surge tank switch and Mass Air Flow (MAF) electrical connectors
  3. Reposition the engine harness to the top of the engine

    Connector Position Assurance (CPA) retainer from the ignition coil harness
    Manifold Absolute Pressure (MAP) sensor connector
    Ignition coil connector(s)
    Engine Coolant Temperature (ECT) sensor electrical connector
    Engine harness bolt and studs
    CPA retainer from the ignition coil harness
    Alternator connector
    Injector harness connector
    Ignition coil harness connector
    Throttle Position (TP) sensor connector
    Electronic Throttle Control (ETC) connector
    Purge valve solenoid connector
  4. Reposition the engine harness to the drivers side of the engine compartment.
    Do NOT try to remove the intake manifold by prying under the sealing surfaces.

    The splash shield is reusable and secured using a snap-in fit. Do not distort the shield during removal.

    Bypass valve vacuum hose from the intake manifold
    EVAP tubes
    Exhaust Gas Recirculation (EGR) valve electrical connector
    EGR pipe bolts from the EGR adapter. Reposition the EGR pipe
    EGR valve pipe gasket and discard
    Secondary Air Injection (AIR) pipe nut from the fuel rail stud, if equipped
    Fuel pressure regulator vacuum hose
    Fuel rail studs and fuel rail, ONLY if replacing the manifold
    Intake manifold bolts

    Intake manifold
    Intake manifold side gaskets and end seals and discard

    Splash shield
To install:
  1. Clean all gasket surfaces completely.
  2. Install or connect the following:
    Make sure the manifold gasket tabs align with the hole in the head gasket.

    Splash shield. Make sure the shield fits properly between the cylinder head.

    Click image to see an enlarged view
    Fig. Make sure that the splash shield snap fits between the cylinder heads-8.1L engines

    New intake manifold end seals
    New intake manifold side gaskets onto the heads. Make sure the stamped This Side Up is showing.
    Intake manifold to the block
    Apply a suitable thread locking material to at least 8 threads of the intake manifold bolts
  3. Install the intake manifold bolts and tighten, in the sequence shown, in 4 passes:
    1. 1st pass: 44 inch lbs. (5 Nm).
    2. 2nd pass: 71 inch lbs. (8 Nm). Check the manifold joints for shifting and fix as necessary.
    3. 3rd pass: 106 inch lbs. (12 Nm).
    4. 4th pass: 11 ft. lbs. (15 Nm).

      Click image to see an enlarged view
      Fig. Intake manifold bolt tightening sequence-8.1L engines
  4. Install the remaining components in the reverse order of the removal procedure.
  5. Fill the cooling system, then connect the negative battery cable
  6. Start the vehicle and verify that there are no leaks.

These details will help.


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