Nissan 240SX/Altima 1993-1998 Repair Guide

Camshaft, Bearings and Lifters

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REMOVAL & INSTALLATION



See Figures 1, 2, 3, 4 and 5



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Fig. Fig. 1: Camshaft cap loosening sequence



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Fig. Fig. 2: Matchmark each camshaft cap, prior to removal, to ensure that they will be installed in their original positions



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Fig. Fig. 3: Carefully remove the camshafts, as to not damage the bearing journals



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Fig. Fig. 4: The intake and exhaust camshaft are different lengths. Note that the exhaust camshaft has slots (arrow) in one end to accept the tang from the distributor



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Fig. Fig. 5: Camshaft cap tightening sequence

  1. Rotate the engine so that the No. 1 cylinder is at TDC on the compression stroke.
  2.  
  3. Remove the distributor assembly.
  4.  
  5. Remove the cylinder head cover.
  6.  
  7. Remove the camshaft sprocket cover.
  8.  
  9. Remove the upper chain guides and timing chain tensioner.
  10.  
  11. Using a piece of mechanic's wire, secure the chain to the sprocket so the chain will not fall off during sprocket removal.
  12.  
  13. Hold the flats of the camshaft with a wrench, just behind the first camshaft bearing cap. Loosen and remove the camshaft sprocket bolts.
  14.  
  15. Remove the camshaft sprockets.
  16.  

The stopper on the camshaft sprocket cover prevents the timing chain from disengaging the idler sprocket.

  1. Remove the camshaft bearing caps in reverse order of the tightening sequence, then remove the camshafts.
  2.  
  3. Remove the valve lifter adjusting shims from the tops of the lifters.
  4.  
  5. Remove the valve lifters from the bores in the cylinder heads.
  6.  

Be sure to note the location and positioning of each valve train component. Install all valve train components in their original positions.

To install:

When installing the valve train components, apply a coating of clean engine oil to the component.

  1. Install the lifters into the lifter bores from which they were removed.
  2.  
  3. Install the valve shims to the lifters from which they came.
  4.  
  5. Install the camshafts in the same position as before removal, then install the camshaft bearing caps; tighten the cap bolts in proper sequence as follows:
    1. Tighten all bolts to 17 inch lbs. (2 Nm).
    2.  
    3. Tighten all bolts to 81-5 inch lbs. (9-12 Nm).When installing the timing chain and sprockets, align the marks on the sprockets with the colored links of the chain.
    4.  

  6.  
  7. Install the camshaft sprockets (with the timing chain attached) and tighten the sprocket bolts to 123-130 ft. lbs. (167-177 Nm). Hold the flats of the camshaft with a wrench, just behind the first camshaft bearing cap while tightening.
  8.  
  9. Install the chain guide between both camshaft sprockets.
  10.  
  11. Install the camshaft sprocket cover.
  12.  
  13. Install the cylinder head cover.
  14.  
  15. Install the distributor assembly.
  16.  

INSPECTION



  1. Clean the camshafts with solvent and wipe dry. Remove light scuffs, scores or nicks from the camshaft machined surfaces with a smooth oil stone.
  2.  

The camshaft(s) must be replaced if the journals are excessively worn or scored.

  1. Check camshaft bores for size, taper, roundness, alignment and finish. If any of these exceed specification, install new camshaft bearings.
  2.  
  3. Inspect the camshaft run-out by setting the No. 1 and No. 4 journals on V-blocks and using a dial indicator. If maximum run-out of camshaft is not within specification, replace the camshaft.
  4.  
  5. Inspect the camshaft lobes for scoring and signs of abnormal wear. Lobe pitting in the general area of the lobe toe does not harm camshaft operation. The camshaft should not be replaced unless the lobe lift loss has exceeded specification or pitting has occurred in the lobe lift area.
  6.  
  7. Inspect the valve lifter and discard the entire tappet if it shows signs of pitting, scoring or excessive wear.
  8.  
  9. Inspect the diameter of the valve lifter and valve lifter bore, and repair or replace components as necessary.
  10.  
  11. Inspect all other valve train components and repair or replace as necessary.
  12.  

 
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