Sienna 1998-1999

Valve Lash (Clearance) Adjustment

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NOTE
Adjust the valve clearance when the engine is cold.

  1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
  2.  
  3. Remove or disconnect the following:

    Negative battery cable. If equipped with an air bag, wait at least 90 seconds before proceeding.
     
    Accelerator/throttle cable from the throttle linkage
     
    Air cleaner cover, air flow meter and air duct assembly
     
    V-bank cover
     
    Emission control valve set
     
    Air intake chamber
     
    Engine harness from the injectors and the ignition coils
     
    Ignition coils and keep them in order for reassembly
     
    Spark plugs
     
    Cylinder head covers
     

  4.  
  5. Turn the crankshaft pulley and align its groove with the timing mark 0 of the No. 1 timing cover.
  6.  
  7. Check that the valve lifters on the No. 1 intake are loose and the No. 1 exhaust are tight. If not, turn the crankshaft 1 complete revolution (360 degrees).
    NOTE
    All measurements should be written down. These recorded measurements will need to be used in conjunction with a mathematical formula to determine the thickness of the replacement shims.

  8.  
  9. Measure the clearance between the valve lifters and the camshaft. Record the measurements on valves No. 1 and 6 intake; No. 2 and 3 exhaust.

    Click image to see an enlarged view

    Fig. Adjust these valves during the 1st step

    1. The intake valve clearance cold is 0.006-0.010 in. (0.15-0.25mm).
    2.  
    3. The exhaust valve clearance cold is 0.010-0.014 in. (0.25-0.35mm).
    4.  

  10.  
  11. Turn the crankshaft 2 / 3 of a revolution (240 degrees). Record the measurements on valves No. 2 and 3 intake; No. 4 and 5 exhaust.

    Click image to see an enlarged view

    Fig. Adjust these valves during the 2nd step

  12.  
  13. Turn the crankshaft another 2 / 3 of a revolution. Record the measurements on valves No. 4 and 5 intake; No. 1 and 6 exhaust.

    Click image to see an enlarged view

    Fig. Adjust these valves during the 3rd step

  14.  
  15. Remove the adjusting shim by turning the crankshaft to position the cam lobe of the camshaft in the up position on the valve to be adjusted. Using a small thin flat bladed tool, turn the valve lifter so that the notches are perpendicular to the camshaft. Press down the valve lifter with tool 09248-55010 part A. Place too 09248-55010 part B between the camshaft and the valve lifter; remove part A.
  16.  
  17. Remove the adjusting shim with a magnet and a small screwdriver.
  18.  
  19. Determine the replacement adjusting shim size by either using the charts or the following formulas:

    Intake: N = T + (A - 0.008 in./0.020mm)
     
    Exhaust: N = T + (A - 0.012 in./0.30mm)
     
    T = Thickness of removed shim
     
    A = Measured valve clearance
     
    N = Thickness of new shim
     

  20.  
  21. Select a new shim with a thickness as close as possible to the calculated value. Install the new replacement shim.
    NOTE
    Shims are available in 17 sizes in increments of 0.0020 in. (0.050mm), from 0.0984 in. (2.500mm) to 0.1299 in. (3.300mm).

  22.  
  23. Recheck the valve clearance.
  24.  
  25. Install or connect the following:

    Cylinder head covers
     
    Spark plugs and the ignition coils
     
    Engine wiring harness to the injectors and the coils
     
    Intake chamber
     
    Emission control valve set
     
    V-bank cover
     
    Air flow meter, air duct and air cleaner cover
     
    Negative battery cable
     

  26.  

 
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