Silverado 2008

Intake Manifold

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Removal & Installation



4.3L Engines

Specific to:

Chevrolet Silverado 1500 2008

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Relieve the fuel system pressure.
  4.  
  5. Disconnect the negative battery cable.
  6.  
  7. Remove or disconnect the following:

    Air intake duct
     
    Wiring harness connectors and brackets from the manifold
     
    Throttle linkage and bracket from the upper manifold
     
    Fuel lines at the rear of the lower intake manifold
     
    Brake booster vacuum hose from the upper intake manifold
     
    Purge solenoid and bracket
     
    Studs and intake manifold attaching bolts, mark for reassembly

    Click image to see an enlarged view

    Fig. Upper intake manifold removal-4.3L engines

     
    Upper intake manifold
     
    Upper radiator hose from the thermostat housing
     
    Heater hoses and the bypass hose from the lower intake manifold
     
    Exhaust Gas Recirculation (EGR) valve
     
    Transmission dipstick tube, if equipped
     
    Positive Crankcase Ventilation (PCV) valve and hoses
     
    Air conditioning compressor and bracket. Without disconnecting, position aside
     
    Alternator bracket and bolt next to the thermostat housing, if needed
     
    Lower intake manifold mounting bolts and the lower manifold

    Click image to see an enlarged view

    Fig. Lower intake manifold removal-4.3L engines



    Click image to see an enlarged view

    Fig. Upper and lower intake manifolds and related components-4.3L engines



    Click image to see an enlarged view

    Fig. Upper engine disassembled view-4.3L engines

     

  8.  

To install:


NOTE
Be sure to use new fasteners, as required.

  1. Clean all gasket mating surfaces thoroughly.
    NOTE
    Apply the proper amount of sealant when assembling this component. Excessive use of sealant can prohibit the component from sealing properly. A component that is not sealed properly can leak and cause extensive engine damage.

  2.  
  3. Apply 0.157 inch patch of adhesive to the cylinder head side on the intake manifold gasket at each end.
    NOTE
    The intake manifold gasket must be installed while the adhesive is still wet to the touch. Be sure to use the proper grade and type adhesive/sealant.



    Click image to see an enlarged view

    Fig. Proper sealant application to cylinder head side of intake manifold-4.3L engines

  4.  
  5. Install the intake manifold gasket onto the cylinder head. Use the gasket locating pins to properly seat the gasket.
    NOTE
    The intake manifold gasket must be installed while the adhesive is still wet to the touch. Be sure to use the proper grade and type adhesive/sealant.



    Click image to see an enlarged view

    Fig. Intake manifold sealant application top front of engine block-4.3L engines



    Click image to see an enlarged view

    Fig. Intake manifold sealant application top rear of engine block-4.3L engines

  6.  
  7. Apply a 0.197 bead of adhesive to the front top of the engine block. Extend the adhesive bead 0.50 inch up onto each intake manifold gasket.
  8.  
  9. Apply a 0.197 bead of adhesive to the rear top of the engine block. Extend the adhesive bead 0.50 inch up onto each intake manifold gasket.
  10.  
  11. Install the intake manifold.
  12.  
  13. Torque the bolts using 3 steps in the sequence shown:
    1. Step 1: 27 inch lbs. (3 Nm).
    2.  
    3. Step 2: 106 inch lbs. (12 Nm).
    4.  
    5. Step 3: 11 ft. lbs. (15 Nm).

      Click image to see an enlarged view

      Fig. Lower intake manifold bolt tightening sequence-4.3L engines

    6.  

  14.  
  15. Install or connect the following:

    Alternator bracket and bolts near the thermostat housing, if removed
     
    Air conditioning compressor
     
    PCV valve and hose
     
    Transmission dipstick tube, if equipped
     
    EGR valve
     
    Upper radiator and bypass hose to the thermostat housing
     

  16.  
  17. Position the upper intake manifold gasket on the lower manifold.
    WARNING
    Be careful not to pinch the injector tubes between the upper and lower manifolds.



    Upper intake manifold. Torque the bolts and studs to 88 inch lbs. (10 Nm).
     
    Purge control bracket and valve
     
    Ignition coil
     
    Brake booster vacuum
     
    Fuel lines
     
    Accelerator cable
     
    Cruise control cable, if equipped
     
    Wiring harness brackets and connections
     
    Air intake duct
     
    Negative battery cable
     

  18.  
  19. Refill and bleed the cooling system.
  20.  
  21. Pressurize the fuel system and check for leaks.
  22.  

4.8L, 5.3L & 6.0L Engines

Specific to:

Chevrolet Silverado 1500 2008


NOTE
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. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Relieve the fuel system pressure.
  4.  
  5. Disconnect the negative battery cable.
  6.  
  7. Remove or disconnect the following:

    Alternator
     
    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.

    Click image to see an enlarged view

    Fig. Always use new gaskets-4.8L, 5.3L and 6.0L engines

     

  8.  
  9. Clean the intake manifold in solvent.
  10.  
  11. Dry the intake manifold with compressed air.
  12.  
  13. Inspect the intake manifold vacuum passages for debris or restrictions.
  14.  
  15. Inspect for damaged or broken vacuum fittings, damaged MAP sensor mounting bore, or broken MAP sensor retaining tabs.
  16.  
  17. Inspect the composite intake manifold assembly for cracks or other damage.
  18.  
  19. Inspect the areas between the intake runners. Inspect all the gasket sealing surfaces for damage.
  20.  
  21. Inspect the fuel injector bores for excessive scoring or damage. Inspect the intake manifold cylinder head deck for warpage.
  22.  
  23. Locate a straight edge across the intake manifold cylinder head deck surface. Position the straight edge across a minimum of two runner port openings.
  24.  
  25. Insert a feeler gauge between the intake manifold and the straight edge. An intake manifold with warpage in excess of 0.118 in. (3mm) over a 7.87 in. (200mm) area is warped and should be replaced.

    Click image to see an enlarged view

    Fig. Upper and lower intake manifolds and related components-4.8L, 5.3L & 6.0L engines

  26.  

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.  
  3. 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).

    Click image to see an enlarged view

    Fig. Lower intake manifold bolt tightening sequence-4.8L, 5.3L & 6.0L 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).
     
    Alternator
     

  4.  

 
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