Sienna 1998-1999

Valve Lash (Clearance) Adjustment


Adjust the valve clearance when the engine is cold.

  1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
  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

  5. Turn the crankshaft pulley and align its groove with the timing mark 0 of the No. 1 timing cover.
  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).
    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.

  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).
    3. The exhaust valve clearance cold is 0.010-0.014 in. (0.25-0.35mm).

  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

  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

  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.
  17. Remove the adjusting shim with a magnet and a small screwdriver.
  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

  21. Select a new shim with a thickness as close as possible to the calculated value. Install the new replacement shim.
    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).

  23. Recheck the valve clearance.
  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