GM Full-Size Trucks 1988-1998 Repair Information

Rocker Arms

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REMOVAL & INSTALLATION



4.8L Engines

See Figure 1

  1. Remove the rocker arm cover.
  2.  
  3. Remove the rocker arm nut.
  4.  



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Fig. Fig. 1: Rocker arm components-gasoline engines

  1. Remove the rocker arm and ball.
  2.  

To install:
  1. 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.
  2.  
  3. Install the nut. See the valve lash adjustment procedure later in this section.
  4.  
  5. Install the cover.
  6.  

4.3L, 5.0L, 5.7L and 7.4L Engines

See Figures 2, 3, 4 and 5

  1. Remove the cylinder head cover.
  2.  
  3. Remove the rocker arm nut. If you are only replacing the pushrod, back the nut off until you can swing the rocker out of the way.
  4.  
  5. Remove the rocker arms and balls as a unit.
  6.  

Always remove each set of rocker arms (one set per cylinder) as a unit.

  1. Lift out the pushrods and pushrod guides.
  2.  



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Fig. Fig. 2: Remove the rocker arm nut



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Fig. Fig. 3: Remove the rocker arms

To install:
  1. Install the pushrods and their guides. Make sure that they seat properly in each lifter.
  2.  
  3. Position a set of rocker arms (for one cylinder) in the proper location.
  4.  

Install the rocker arms for each cylinder only when the lifters are off the cam lobe and both valves are closed.

  1. 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.
  2.  
  3. Install the nuts and tighten alternately as detailed in the valve lash adjustment procedure later in this section.
  4.  



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Fig. Fig. 4: Tag the pushrods before removal, as they must be installed in the same order



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Fig. Fig. 5: A piece of cardboard may be used to hold the pushrods in order

6.2L and 6.5L Diesel Engines

See Figures 6 and 7

Rotate the engine until the mark on the crankshaft balancer is at the 2 o'clock position. Rotate the crankshaft counterclockwise 31/2in. (88mm) aligning the crankshaft balancer mark with the first lower water pump bolt, about the 12:30 position. This will ensure that no valves are close to a piston crown

  1. Remove the cylinder head cover.
  2.  
  3. The rocker assemblies are mounted on two short rocker shafts per cylinder head, with each shaft operating four rockers. Remove the two bolts which secure each rocker shaft assembly, and remove the shaft. Mark the shafts so they can be installed in their original locations.
  4.  



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Fig. Fig. 6: Rocker shaft assembly-diesel engines



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Fig. Fig. 7: Removing the rocker arm retainers

  1. Remove the 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, make 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 and then slide off the rockers.
  4.  

To install:
  1. Make sure first that the rocker arms and springs go back on the shafts in the exact order in which they were removed. Its a good idea to coat them with engine oil.
  2.  
  3. Center the rockers on the corresponding holes in the shaft and install new plastic retainers using a 1 / 2 in. (13mm) drift.
  4.  
  5. Install the pushrods with their marked ends up.
  6.  
  7. Install the rocker shaft assemblies and make sure that the ball ends of the pushrods seat themselves in the rockers.
  8.  
  9. 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.
  10.  
  11. Install the rocker shaft bolts and tighten them to 40 ft. lbs. (55 Nm).
  12.  
  13. Install the cylinder head cover.
  14.  

 
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