Metro, Prizm 2000-2002

Valve Lash (Clearance) Adjustment

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1.0L Engine



Lash adjusters, located between the camshaft and valve stems, are used to adjust the valve clearance to 0 lash automatically at all times. Adjustment is not required or possible.

Prizm And 1.3L Metro



  1. Before servicing the vehicle, refer to the precautions section.
  2.  
  3. Remove the negative battery cable.
  4.  
  5. Disconnect the ignition wires.
  6.  
  7. Remove the rocker arm cover.
  8.  
  9. Turn the crankshaft until the piston in No. 1 cylinder is at Top Dead Center (TDC) on the compression stroke. Align the groove in the crankshaft pulley with the 0 mark on the timing belt cover. Be sure the camshaft gears are aligned.
  10.  
  11. The intake valve clearance should be 0.006-0.010 in. (0.15-0.25mm) and the exhaust valve clearance should be 0.010-0.014 in. (0.25-0.35mm).
  12.  
  13. Using a feeler gauge, measure the clearance between the camshaft and valve lifter shim at the No. 1 cylinder intake and exhaust valves, the No. 2 cylinder intake valves and the No. 3 cylinder exhaust valves. Record the clearance measurements for all valves that are not within specification, in order to determine the required replacement shims.
  14.  
  15. Rotate the crankshaft pulley 1 full turn (360 degrees) and check the clearance at the No. 2 cylinder exhaust valves, the No. 3 cylinder intake valves and the No. 4 cylinder intake and exhaust valves. Record the clearance measurements for all valves that are not within specification, in order to determine the required replacement shims.

    Click image to see an enlarged view

    Fig. Using the valve clearance adjustment tool set to hold the lifter

  16.  
  17. For valves requiring adjustment, proceed as follows:
    1. Be sure the base of the camshaft lobe is directly over the valve (camshaft lobe pointing away from the valve).
    2.  
    3. Insert tool J-3987-1 between the camshaft and lifter adjustment shim, to compress the valve spring and push the lifter down.
    4.  
    5. Insert tool J-39871-2 between the camshaft and the lifter, to hold the lifter away from the camshaft. Position the bottom edge of the tool on the lifter.
    6.  
    7. Using a small screwdriver and a magnet, remove the adjustment shim from the top of the lifter.
    8.  
    9. Use the micrometer to measure the thickness of the removed shim. Determine the thickness of the new shim using the formula below. For the purposes of the following formula, T = Thickness of the shim removed; A = Valve clearance measured; N = Thickness of the required new shim.
    10.  

  18.  
  19. For the intake camshaft valves: N = T + A - 0.008 in. (0.20mm).
  20.  
  21. For the exhaust camshaft valves: N = T + A - 0.010 in. (0.25mm).
    1. Select a shim closest to the calculated thickness. Shims are available in 16 sizes, in increments of 0.002 in. (0.050mm), from 0.1004 in. (2.55mm) to 0.1299 in. (3.30mm).
    2.  
    3. Install the shim on the valve lifter and remove tool J-39871-2. Recheck the valve clearance.
    4.  

  22.  
  23. Install the rocker arm cover, using a new gasket and torque the nuts to 53 inch lbs. (6 Nm).
  24.  
  25. Connect the ignition wires.
  26.  
  27. Connect the negative battery cable.
  28.  
  29. Run the engine and check operation.
  30.  

 
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