Sentra 1998

Valve Lash (Clearance) Adjustment

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1.6L Engine



Adjusting

Specific to:

Nissan Sentra 1997-1999

  1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
  2.  
  3. If an adjustment is necessary, adjust the valve clearance while engine is cold by removing the adjusting shim. The adjusting shim can be removed by using the following procedures:
    1. Turn the crankshaft so the camshaft lobe of the valve to be adjusted is pointed straight up.
    2.  
    3. Turn the lifter so the notch is pointed towards the center of the cylinder head; this will facilitate the shim removal process.
    4.  
    5. Using a depressor tool, push down on the lifter and insert a keeper tool on the edge of the lifter to keep the lifter in the depressed position.
    6.  
    7. Remove the depressor tool and remove the shim with a magnet.
    8.  

  4.  
  5. Determine the replacement adjusting shim size by using the following procedures and formula:
    1. Using a micrometer determine thickness of the removed shim.
    2.  
    3. Calculate the thickness of a new adjusting shim so valve clearance is within the specified values.
    4.  
    5. R = thickness of the removed shim.
    6.  
    7. N = thickness of the new shim.
    8.  
    9. M = measured valve clearance.

      Intake shim determination formula: N = R + (M - 0.0146 in. or 0.37mm)
       
      Exhaust shim determination formula: N = R + (M - 0.0157 in. or 0.40mm)
       

    10.  

  6.  

Shims are available in different sizes from 0.0772-0.1055 in. (1.96-2.68mm) in increments of 0.0008 in. (0.02mm). The thickness is stamped on the shim; this side is always installed facing down. Select new shims with thickness as close as possible to calculated valve and install it in the lifter.

  1. Install the new shim onto the lifter.
  2.  
  3. Depress the lifter and remove the keeper tool. Remove the depressor tool and recheck the valve clearance. Repeat this procedure for any other valves requiring adjustment.
  4.  
  5. Install the cylinder head cover and spark plugs when all valve adjustments are finished.
  6.  

Checking

Specific to:

Nissan Sentra 1997-1999

  1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
  2.  
  3. Run the engine until it reaches normal operating temperature and shut if off.
  4.  
  5. Remove the cylinder head cover and all the spark plugs.
  6.  
  7. Set the No. 1 cylinder at Top Dead center (TDC) on its compression stroke. Align the pointer with the TDC mark on the crankshaft pulley. Check that the valve lifters on the No. 1 cylinder are loose and valve lifters on the No. 4 cylinder are tight. If not, turn the crankshaft 1 revolution (360 degrees) and align the pointer with the TDC mark on the crankshaft pulley.
  8.  
  9. Check the following valves:

    Both No. 1 intake valves
     
    Both No. 1 exhaust valves
     
    Both No. 2 intake valves
     
    Both No. 3 exhaust valves
     

  10.  
  11. Using a feeler gauge, measure the clearance between the valve lifter and the camshaft. Record any valve clearance measurements which are out of specification.

    Click image to see an enlarged view

    Fig. Measure the clearance of the valves indicated when the No. 1 piston is at TDC on compression

  12.  
  13. Turn the crankshaft 1 revolution (360 degrees) and align the mark on the crankshaft pulley with the pointer. Check the following valves:

    Both No. 2 exhaust valves
     
    Both No. 3 intake valves
     
    Both No. 4 intake valves
     
    Both No. 4 exhaust valves
     

  14.  
  15. Using a feeler gauge, measure the clearance between the valve lifter and the camshaft. Record any valve clearance measurements which are out of specification.

    Click image to see an enlarged view

    Fig. Measure the clearance of the valves indicated when the No. 4 piston is at TDC on compression

  16.  
  17. If all the valve clearances are within specification, install the cylinder head cover and the spark plugs.
  18.  

2.0L Engine



The engine is equipped with hydraulic lash adjusters. The valve lash is not adjustable.

 
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