Nissan Pick-ups and Pathfinder 1970-1988

Rocker Arm/Shaft Assembly

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REMOVAL & INSTALLATION



Z20, Z22, Z24 and Z24i Engines

See Figures 1, 2, 3, 4, 5, 6, 7 and 8

  1. Remove the cylinder head cover. The rocker shaft assembly is removed by simply unthreading the retaining bolts.
  2.  

When removing the bolts, DO NOT REMOVE THE NO.1 AND NO. 5 BRACKET BOLTS SINCE THE ROCKER SHAFT BRACKET AND ROCKER ARM WILL SPRING OUT!

  1. Remove the rocker shaft bracket, then slide the valve rockers and springs off of the rocker shaft. Be absolutely sure to keep all parts in the order in which they were removed; they must be reassembled in the same order.
  2.  
  3. Inspect the rocker arms and shaft for damage, replace as necessary.
  4.  

To install:
  1. Slide the springs and rockers onto the shafts in the order that they were removed.
  2.  
  3. The intake rocker shaft has a slit on its leading edge, but the exhaust shaft does not. Additionally, each shaft has a punch mark on its leading edge. The shafts should be assembled with these marks facing upward as they are used for oil hole identification.
  4.  
  5. The intake and exhaust rockers for the Nos. 1 and 3 cylinders are the same and are identified by the mark 1 . The same holds true for the rockers on Nos. 2 and 4 cylinders; they are identified with a 2 .
  6.  
  7. The rocker shaft brackets are also marked as to their original location; simply match them to the like marks on the cylinder head.
  8.  
  9. At this point, reinsert a bracket bolt into holes for the No. 1 and No. 5 brackets (any bolt is fine). This will insure that the assembly stays together while you mount it on the head.
  10.  
  11. Mount the rocker shaft assembly on the cylinder head in a manner that accommodates the camshaft knock pin and then tighten the retaining bolts gradually, in two or three stages to 11-18 ft. lbs. (15-25 Nm).
  12.  
  13. Refer to Engine Electrical for valve lash adjustment.
  14.  



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Fig. Fig. 1: Rocker shaft assembly-Z20, Z22, Z24 and Z24i engines



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Fig. Fig. 2: Rocker arm installation-Z20, Z22, Z24 and Z24i engines



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Fig. Fig. 3: Rocker shaft installation-Z20, Z22, Z24 and Z24i engines



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Fig. Fig. 4: Rocker shaft/arm identification-Z20, Z22, Z24 and Z24i engines



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Fig. Fig. 5: Make sure that the camshaft knockpin is in the UP position-Z20, Z22, Z24 and Z24i engines



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Fig. Fig. 6: Removing the rocker arm/shaft assembly bolts



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Fig. Fig. 7: Removing the rocker arm/shaft assembly



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Fig. Fig. 8: View of the rocker arm/shaft-keep all bolts in order for correct installation

VG30i Engines

See Figure 9

  1. Remove the cylinder head covers.
  2.  
  3. Remove the rocker arm shaft-to-cylinder head bolts and lift the rocker arm/shaft assembly from the cylinder head.
  4.  
  5. Separate the rocker arms from the shaft.
  6.  

When separating the rocker arms from the rocker arm shafts, be sure to keep the parts in order for reinstallation purposes.

  1. Check the rocker arms, the shafts, the valves and the valve lifter for damage. If necessary, replace the damaged components.
  2.  


CAUTION
When installing the rocker arm shafts, be certain that they are installed in their original positions.

To install:
  1. Slide the rocker arms onto the shafts and then install the shaft/arm assemblies onto the cylinder head in the proper positions.
  2.  
  3. Make sure the camshaft knock pin is at the top of the camshaft and that the lobe is not in the lifted position. Set the No. 1 piston at TDC of its compression stroke and then tighten the rocker shaft bolts for the Nos. 2, 4 and 6 cylinders. Set the No. 4 piston at TDC of its compression stroke and tighten the Nos. 1, 3 and 5 cylinder rocker shaft bolts. Tighten all bolts gradually, in two or three stages to 13-16 ft. lbs. (18-22 Nm).
  4.  
  5. Refer to Engine Electrical for valve lash adjustment.
  6.  
  7. Install the cylinder head cover.
  8.  



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Fig. Fig. 9: Rocker shaft installation direction-VG30i engine

SD22 and SD25 Engines

See Figure 10

  1. Remove the cylinder head cover.
  2.  
  3. Remove the shaft retaining bolts evenly, from the center towards the ends.
  4.  
  5. Lift the shaft assembly off the head. Remove the cotter pin, washer and outer spring from the end of the shaft.
  6.  
  7. Slide the rocker arm and bracket off the shaft. It may be necessary to immerse the assembly in water heated to 160°F (71°C) for a few minutes to free the rocker arms. NEVER HAMMER THEM OFF!
  8.  

To install:
  1. Install the rocker arms and brackets onto the shaft and then install the O-ring, a new washer and cotter pin at the shaft outer ends.
  2.  
  3. Position the shaft/arm assembly on the cylinder head and tighten the mounting bolts gradually, in two or three stages to 14-18 ft. lbs. (20-22 Nm).
  4.  
  5. Refer to Engine Electrical for valve lash adjustment.
  6.  



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Fig. Fig. 10: Exploded view of the rocker assembly-SD22 and SD25 engines

INSPECTION



See Figures 11, 12 and 13

The oil clearance between the rocker arm and shaft is measured in two steps. Measure the outside diameter of the rocker shaft with a micrometer. Measure the inside diameter of the rocker arms with a dial indicator. The difference between the rocker arm inner diameter and the shaft outer diameter is the oil clearance. Clearance specifications are as follows:



Z20: 0.0003-0.0019 in. (0.008-0.050mm)
 
Z22: 0.0003-0.0019 in. (0.008-0.050mm)
 
Z24: 0.0003-0.0019 in. (0.008-0.050mm)
 
Z24i: 0.0003-0.0019 in. (0.008-0.050mm)
 
VG30i: 0.0003-0.0019 in. (0.008-0.050mm)
 
SD22: 0.0008-0.0020 in. (0.02-0.05mm)
 
SD25: 0.0008-0.0020 in. (0.02-0.05mm)
 

If specifications are not within these ranges, replace either the rocker shaft or rocker arm. Clearance can also be checked by moving the rocker arm laterally on the shaft when assembled. There should be little or no movement.

While disassembled, check the cam follower end (the flat end that contacts the camshaft) of the rocker arm for excess wear. The surface should be smooth and shiny. If excess wear is evident, also check the lobe of the camshaft, it may also be worn.

Reassemble the rocker shaft assemblies in the exact opposite order or removal. Accelerated camshaft wear and/or sloppy valve action will result if rocker arms are mixed and end up operating against the wrong cam lobes.



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Fig. Fig. 11: Check the rocker arm-to-shaft wear by wiggling the arm laterally on the shaft-Little or no movement should be felt



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Fig. Fig. 12: Measure the outside diameter of the rocker shaft with a outside micrometer



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Fig. Fig. 13: Measure the inside diameter of the rocker shaft with a inside micrometer

 
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