Express, Savana, G1500, G2500, G3500, 1998-2005

Rocker Arms & Shafts

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Removal & Installation



4.3L Engine
  1. Remove or disconnect the following:
    NOTE
    Always remove each set of rocker arms (1 set per cylinder) as a unit.



    Engine cover
     
    Cylinder head cover
     
    Rocker arm nut. If you are only replacing the pushrod, back the nut off until you can swing the rocker out of the way.
     
    Rocker arms and balls as a unit
     



    Pushrods and pushrod guides
     

  2.  

To install:

  1. Install or connect the following:

    Pushrods and their guides. Be sure that they seat properly in each lifter.
     

  2.  
  3. Position a set of rocker arms (for 1 cylinder) in the proper location.
    NOTE
    Install the rocker arms for each cylinder only when the lifters are off the cam lobe and both valves are closed.



    Click image to see an enlarged view

    Fig. Exploded view to the rocker arm and related components-4.3L engines

  4.  
  5. Coat the replacement rocker arm with Molykote® or its equivalent, and the rocker arm and pivot with SAE 90 gear oil, and install the pivots.

    Nuts and finger tighten
     

  6.  
  7. Rotate the crankshaft balancer to position the crankshaft balancer alignment mark (1) 57-63 degrees clockwise or counterclockwise from the engine front cover alignment tab (2).

    Click image to see an enlarged view

    Fig. Positioning the crankshaft balancer alignment marks-4.3L engines

  8.  
  9. Tighten the rocker arm nuts to 22 ft. lbs. (30 Nm).
  10.  
  11. Install the rocker arm cover.
  12.  
  13. Install the engine cover.
  14.  

4.8L, 5.3L & 6.0L Engines

NOTE
Do not remove the ignition coils from the valve rocker arm cover unless required. Do not remove the oil fill tube from the cover unless service is required. If the oil fill tube has been removed from the cover, install a NEW tube during assembly.



Click image to see an enlarged view

Fig. Rocker arm removal-4.8L, 5.3L and 6.0L engines

On the right side:

  1. Remove or disconnect the following:

    Ignition coil bracket bolts from the rocker arm cover, if required
     
    Ignition coil and bracket assembly from the cover
     
    Valve rocker arm cover bolts
     
    Valve rocker arm cover
     
    Gasket from the cover. Discard the gasket. The bolt grommets may be reused if not damaged.
     
    Oil fill cap from the oil fill tube
     
    Oil fill tube, if required. Discard the oil fill tube.
     

  2.  

On the left side:


NOTE
Do not remove the Positive Crankcase Ventilation (PCV) valve grommet from the cover unless service is required.

  1. Remove or disconnect the following:

    Ignition coil bracket bolts from the rocker arm cover (if required)
     
    Ignition coil and bracket assembly from the cover
     
    Valve rocker arm cover bolts
     
    Valve rocker arm cover
     
    Gasket from the cover. Discard the gasket. The bolt grommets may be reused if not damaged.
     
    Valve rocker arm bolts
     
    Valve rocker arms
     
    Valve rocker arm pivot support
     
    Pushrods
     

  2.  

To install:


NOTE
Valve lash is built in. No valve adjustment is required.

  1. Lubricate the valve rocker arms and pushrods with clean engine oil.
  2.  
  3. Lubricate the flange of the valve rocker arm bolts with clean engine oil.
  4.  
  5. Lubricate the flange or washer surface of the bolt that will contact the valve rocker arm.
  6.  
  7. Install or connect the following:
    NOTE
    Make sure that the pushrods seat properly to the valve lifter sockets.


    NOTE
    Make sure that the pushrods seat properly to the ends of the rocker arms.



    Valve rocker arm pivot support
     



    Pushrods
     



    Rocker arms and bolts. DO NOT tighten the rocker arm bolts at this time
     

  8.  
  9. Rotate the crankshaft until number one piston is at top dead center of compression stroke. In this position, cylinder number one rocker arms will be off lobe lift. The engine firing order is 1, 8, 7, 2, 6, 5, 4, 3. Cylinders 1, 3, 5 and 7 are left bank. Cylinders 2, 4, 6, and 8 are right bank.
  10.  
  11. With the engine in the number one firing position, tighten the following valve rocker arm bolts:
    1. Tighten exhaust valve rocker arm bolts 1, 2, 7, and 8 to 22 ft. lbs. (30 Nm).
    2.  
    3. Tighten intake valve rocker arm bolts 1, 3, 4, and 5 to 22 ft. lbs. (30 Nm).
    4.  

  12.  
  13. Rotate the crankshaft 360 degrees. Tighten the following valve rocker arm bolts:
    1. Tighten exhaust valve rocker arm bolts 3, 4, 5, and 6 to 22 ft. lbs. (30 Nm).
    2.  
    3. Tighten intake valve rocker arm bolts 2, 6, 7, and 8 to 22 ft. lbs. (30 Nm).
    4.  

  14.  

On the right side:


NOTE
The valve rocker arm cover bolt grommets may be reused. If the oil fill tube has been removed from the valve rocker arm cover, install a NEW oil fill tube during assembly.

  1. Lubricate the O-ring seal of the NEW oil fill tube with clean engine oil.
  2.  
  3. Install or connect the following:

    NEW oil fill tube into the rocker arm cover and rotate the tube clockwise until locked in the proper position
     
    Oil fill cap into the tube and rotate clockwise until locked in the proper position
     
    NEW cover gasket into the valve rocker arm cover
     
    Valve rocker arm cover onto the cylinder head
     

  4.  
  5. Install the cover bolts with grommets. Tighten the valve rocker arm cover bolts to 106 inch lbs. (12 Nm).
  6.  
  7. Apply threadlock GM P/N 12345382 or equivalent to the threads of the bracket bolts. Install the ignition coil and bracket assembly and bolts. Tighten the ignition coil and bracket assembly studs to 106 inch lbs. (12 Nm).
  8.  

On the left side:


NOTE
DO NOT reuse the valve rocker arm cover gasket. The valve rocker arm cover bolt grommets may be reused. If the vapor vent grommet has been removed from the valve rocker arm cover, install a NEW vapor vent gourmet during assembly.

  1. Install or connect the following:

    NEW cover gasket (1) into the valve rocker arm cover
     
    Valve rocker arm cover onto the cylinder head
     

  2.  
  3. Install the cover bolts with grommets. Tighten the valve rocker arm cover bolts to 106 inch lbs. (12 Nm).
  4.  
  5. Apply threadlock GM P/N 12345382 or equivalent to the threads of the bracket bolts. Install the ignition coils and bracket assembly and bolts. Tighten the ignition coil and bracket assembly bolts to 106 inch lbs. (12 Nm).
  6.  

6.5L Engine
  1. Remove or disconnect the following:
    NOTE
    Rotate the engine until the mark on the crankshaft balancer is at the 2 o'clock position. Rotate the crankshaft counterclockwise 3 1 / 2 in. (88mm) aligning the crankshaft balancer mark with the first lower water pump bolt, at about the 12:30 position. This will ensure that no valves are close to a piston crown


    NOTE
    The rocker assemblies are mounted on 2 short rocker shafts per cylinder head, with each shaft operating 4 rockers. 2 bolts secure each rocker shaft assembly, Mark the shafts so they can be installed in their original locations.



    Engine cover
     



    Cylinder head cover
     
    Rocker shaft assembly
     



    Click image to see an enlarged view

    Fig. Rocker shaft assembly and related components-diesel engines



    Pushrods. The pushrods MUST be installed in the original direction! A paint stripe usually identifies the upper end of each rod, but if you can't see it, be sure to mark each rod yourself.
     

  2.  
  3. Insert a small prybar into the end of the rocker shaft bore and break off the end of the nylon retainers. Pull off the retainers with pliers, then slide off the rockers.
  4.  

To install:

  1. Be sure first that the rocker arms and springs go back on the shafts in the exact order in which they were removed. It-s a good idea to coat them with engine oil.
  2.  
  3. Center the rockers on the corresponding holes in the shaft
  4.  
  5. Install or connect the following:

    New plastic retainers using a 1 / 2 in. (13mm) drift
     
    Pushrods with there marked ends up
     
    Rocker shaft assemblies and be sure that the ball ends of the pushrods seat themselves in the rockers
     

  6.  
  7. Rotate the engine clockwise until the mark on the torsional damper aligns with the 0 on the timing tab. Rotate the engine counterclockwise 3 1 / 2 in. (88mm) measured at the damper. You can estimate this by checking that the mark on the damper is now aligned with the FIRST lower water pump bolt. BE CAREFUL! This ensures that the piston is away from the valves.

    Rocker shaft bolts and tighten to 40 ft. lbs. (55 Nm)
     
    Cylinder head cover
     
    Engine cover
     

  8.  

6.6L Engine
  1. Remove the lower valve (rocker arm) covers
  2.  
  3. Loosen the valve clearance lock nuts on each rocker arm
  4.  
  5. Loosen the valve clearance adjusting screw on each rocker arm to relieve tension on the valve train
    NOTE
    The rocker arm bolts retain the rocker arms on the shaft. Do not remove the bolts from the rocker arm shaft brackets.

  6.  
  7. Loosen the rocker arm shaft bolts in the proper sequence, leaving the bolts in the rocker arm shaft brackets.

    Click image to see an enlarged view

    Fig. Rocker arm shaft bolt loosening sequence-6.6L engines

  8.  
  9. Remove or disconnect the following:

    Rocker arm shaft assemblies from the cylinder head
     
    Valve bridge pins
     
    Valve bridges
     
    Valve push rods
     

  10.  
  11. Clean all parts in a suitable solvent. Disassemble the rocker arm shaft as necessary.
  12.  

To install:

  1. Lubricate the rocker arm shaft and the inside of the rocker arms with engine oil.
  2.  
  3. If disassembled, install or connect the following:

    Rocker arm bracket on one end of the rocker arm shaft with the bolt
     
    Rocker arm intake, spring, exhaust and the bracket with bolt. Continue in the same sequence to the last bracket.
     
    Push the bracket to compress the springs and then install the bolt
     

  4.  
  5. Lubricate the top of the valves, the valve bridge stem, the valve bridge and the valve bridge pins.
  6.  
  7. Install or connect the following:

    Valve bridge pins
     
    Valve bridges
     
    Pushrods. Make sure it is fully installed by gently pulling up on it. You should feel resistance from the pushrod trying to lift the valve lifter
     

  8.  
  9. Use clean engine oil to lubricate the rocker arm shaft bolt threads, tops of the push rods, rocker arms and rocker arm shaft.

    Rocker arm shaft assembly to the cylinder head
     
    Rocker arm shaft assembly bolts and tighten, in the proper sequence to 30 ft. lbs. (40 Nm)

    Click image to see an enlarged view

    Fig. Rocker arm shaft tightening sequence-6.6L engines

     

  10.  
  11. Adjust the valve clearance, as follows:
    1. Remove the fan clutch.
    2.  
    3. Remove both upper valve covers.
    4.  
    5. Rotate the engine in the normal direction and place the No. 1 piston at Top Dead Center (TDC) of the compression stroke. The No. 1 cylinder is at the right side front. While turning the engine, watch the intake valve to open and close. Align the mark on the crankshaft balancer with the pointer on the engine.
    6.  
    7. Loosen the valve clearance adjusting screws for the valve being adjusted.
    8.  
    9. Insert the feeler gauge between the tip of the rocker arm and the valve bridge.
    10.  
    11. Adjust the intake and the exhaust valve clearance to 0.012 in. (0.3mm) with the engine cold. Refer to the figure for the valves that can be adjusted TDC of the compression stroke.
    12.  
    13. Tighten the valve adjusting screw lock nut to 16 ft. lbs. (22 Nm).

      Click image to see an enlarged view

      Fig. Location of the valves that are adjusted at TDC of the compression stroke-6.6L engines

    14.  
    15. Turn the engine one rotation in the normal direction and put the No. 1 piston at TDC of the exhaust stroke to adjust the remaining valve clearance. While turning the engine, watch the exhaust valve to open and close. Align the mark on the crankshaft balancer with the pointer on the engine.
    16.  
    17. Loosen the valve clearance adjusting screws for the valves being adjusted.
    18.  
    19. Insert the feeler gauge between the tip of the rocker arm and the valve bridge.
    20.  
    21. Adjust the intake and the exhaust valve clearance to 0.012 in. (0.3mm) with the engine cold. Refer to the figure for the valves that can be adjusted TDC of the exhaust stroke.
    22.  
    23. Tighten the valve adjusting screw lock nut to 16 ft. lbs. (22 Nm).

      Click image to see an enlarged view

      Fig. Location of the valves that are adjusted at TDC of the exhaust stroke-6.6L engines

    24.  

  12.  
  13. Install the upper and lower valve cover and fan clutch, as necessary.
  14.  

8.1L Engine

NOTE
Always make sure to keep all removed valve train components in order for reassembly. They must be installed in the same position from which they were removed.

  1. Remove or disconnect the following:
    NOTE
    The intake pushrods are shorter than the exhaust pushrods.



    Valve (rocker arm) cover
     
    Rocker arm nuts, balls and rocker arms
     



    Pushrods
     
    Rocker arm guides and pushrod guides
     

  2.  
  3. Clean and inspect all components for damage.
  4.  

To install:

  1. Apply a suitable sealer to the rocker arm stud-to-cylinder head threads.
  2.  
  3. Install or connect the following:

    Pushrod guides and rocker arm studs. Tighten to 37 ft. lbs. (50 Nm).
     
    Pushrods
     

  4.  
  5. Coat the rocker arm and ball bearing surfaces with a suitable prelube.

    Rocker arms, balls and nuts. Tighten the nuts slowly to 26 ft. lbs. (35 Nm) while guiding the tips of the rocker arms over the tips of the valves.
     
    Valve (rocker arm) cover
     

  6.  

 
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