Nissan Pick-ups and Pathfinder 1989-1995

Rocker Arm/Shaft Assembly

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REMOVAL & INSTALLATION



Z24i Engine

See Figures 1 through 5

  1. Remove the cylinder head cover. The rocker shaft assembly can be removed by simply unthreading its 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 position and location.
  2.  



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Fig. Fig. 1: Rocker shaft assembly-Z24i engine



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Fig. Fig. 2: Rocker arm installation-Z24i engine



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Fig. Fig. 3: Rocker shaft installation-Z24i engine



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Fig. Fig. 4: Rocker shaft/arm identification-Z24i engine



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Fig. Fig. 5: Make sure that the camshaft knockpin is in the UP position-Z24i engine

47

  1. Inspect the rocker arms and shaft for damage; replace as necessary.
  2.  

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 one 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.  

The intake and exhaust rockers for Cylinders No. 1 and 3 are the same and are identified by the mark "1''. The same holds true for the rockers on Cylinders No. 2 and 4; they are identified with a "2''.

  1. The rocker shaft brackets are also marked as to their original location; simply match them to the like marks on the cylinder head.
  2.  
  3. At this point, reinsert a bracket bolt into holes for the No. 1 and No. 5 brackets. This will insure that the assembly stays together while you mount it on the head.
  4.  
  5. Mount the rocker shaft assembly on the cylinder head in a manner that accommodates the camshaft knock pin, then tighten the retaining bolts gradually, in two or three stages, to 11-18 ft. lbs. (15-25 Nm).
  6.  
  7. Before installing the cylinder head cover, please refer to Engine Performance and Tune-up for valve lash adjustment.
  8.  

KA24E Engine

See Figures 6, 7, 8 and 9

The KA24E engine is unique in that its hydraulic lifters are installed inside the rocker arm assemblies. If a hydraulic lifter is kept on its side, even when installed in the rocker arm assembly, there is the possibility of air entering it. After removal, always set rocker arm assembly straight up.

  1. Remove the cylinder head cover. The rocker shaft assembly can be removed by simply removing its retaining bolts.
  2.  

When removing the bolts, loosen them in two or three stages, from the outside to the inside, in the proper sequence.



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Fig. Fig. 6: Rocker shaft assembly loosening sequence-KA24E engine



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Fig. Fig. 7: Rocker shaft identification-KA24E engine



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Fig. Fig. 8: Rocker arm retainer positioning-KA24E engine



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Fig. Fig. 9: Rocker shaft assembly torque sequence-KA24E engine

  1. Remove the rocker shaft retainers, 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 position and location.
  2.  
  3. Inspect the rocker arms and shaft for damage; and replace as necessary.
  4.  

To install:
  1. Slide the springs and rockers onto the shafts in the order that they were removed.
  2.  
  3. Install the rocker retainers so that the cutouts are facing in the direction shown in the illustration.
  4.  
  5. The intake rocker shaft has a single punch mark on its leading edge, but the exhaust shaft has two punch marks. The shafts should be assembled with these marks facing upward, as they are used for oil hole identification.
  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. Mount the rocker shaft assembly on the cylinder head in a manner that accommodates the camshaft knock pin, then tighten the retaining bolts gradually, in two or three stages to 27-30 ft. lbs. (37-41 Nm). Follow the tightening sequence shown in the illustration.
  10.  

VG30i and VG30E Engines

See Figures 10, 11, 12 and 13

  1. Remove the cylinder head cover(s).
  2.  
  3. Remove the rocker arm shaft-to-cylinder head bolts and lift the rocker arm/shaft assembly from the cylinder head.
  4.  



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Fig. Fig. 10: Rocker shaft installation direction-6-cylinder engines



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Fig. Fig. 11: View of the rocker shaft installed-all 6-cylinder engines are similar



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Fig. Fig. 12: After removing the rocker shaft assembly, keep all bolts in the proper order if possible



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Fig. Fig. 13: Use a torque wrench when installing the rocker shaft assembly

  1. Separate the rocker arms from the shaft.
  2.  

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.  

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

  1. Slide the rocker arms onto the shafts, then install the shaft/arm assemblies onto the cylinder head in their 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. If servicing the left-side cylinder head, set the No. 1 piston at TDC of its compression stroke, then tighten the rocker shaft bolts for cylinder No. 2, 4 and 6 cylinders. If servicing the right-side cylinder head, set the No. 4 piston at TDC of its compression stroke and tighten the rocker shaft bolts for cylinder No. 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. Install the cylinder head cover(s).
  6.  

INSPECTION



See Figures 14, 15 and 16

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. The clearance specifications are as follows:



Z24i: 0.0003-0.0019 in. (0.008-0.050mm)
 
VG30i: 0.0003-0.0019 in. (0.008-0.050mm)
 
KA24E: 0.0005-0.0020 in. (0.012-0.050mm)
 
VG30E: 0.0003-0.0019 in. (0.008-0.050mm)
 

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.



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Fig. Fig. 14: 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. 15: Measure the outside diameter of the rocker shaft with an outside micrometer



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Fig. Fig. 16: Measure the inside diameter of the rocker shaft with an inside micrometer

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, check the lobe of the camshaft, since it may also be worn.

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

 
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