Toyota Previa 1991-1997 Repair Information

Valve Lash

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ADJUSTMENT



See Figures 1 through 9



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Fig. Fig. 1: The valve lash clearance is marked on a label under the hood

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the right side seat and engine service hole cover as follows:
    1. Remove the three screws and the scuff plate.
    2.  
    3. Unbolt and disconnect the right seat belt from the front floor panel.
    4.  
    5. Remove the four bolts holding the right front seat.
    6.  
    7. Remove the two bolts and the right front seat leg.
    8.  
    9. Remove the jack, the jack stand and the tool bag.
    10.  
    11. Remove the engine service hole cover.
    12.  

  4.  
  5. Remove the No. 2 cylinder head cover with the gasket.
  6.  
  7. Remove the PCV hose and disconnect the four spark plug wires from the spark plugs.
  8.  
  9. Remove the No. 2 cord clamp support plate.
  10.  
  11. Remove the No. 1 cylinder head cover and the gasket.
  12.  
  13. Install a bolt 12mm x 1.25mm and nut to the equipment drive shaft.
  14.  



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Fig. Fig. 2: Insert the service bolt into the pulley


WARNING
When rotating the driveshaft or engine by hand, this can be done by inserting a service bolt 12mm x 1.25mm with a nut into the screw hole at the end of the drive shaft. After doing the operation, do not forget to remove the service bolt and nut. If the service bolt is left installed, the bolt head may be hit and damage the cooling fan.

  1. Set the No. 1 cylinder to TDC in the compression stroke.
    1. Turn the equipment drive shaft with a wrench to align the timing marks at TDC. Set the groove on the crankshaft pulley to the 0 position.
    2.  
    3. Check that the valve lifters on the No. 1 cylinder are loose and the valve lifters on the No. 4 are tight. If not, turn the equipment drive shaft one complete revolution and align the marks as above.
    4.  

  2.  



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Fig. Fig. 3: Adjust these valve in the first pass

  1. Inspect the valve clearance.
    1. Measure the clearance between the valve lifter and the camshaft. Measure the first and second intake and the first and third exhaust valves.
    2.  
    3. Turn the equipment drive shaft one revolution (360°) and align the marks as above. Measure the third and fourth intake and the second and fourth exhaust valves.
    4.  

  2.  



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Fig. Fig. 4: Adjust these valve in the second pass

  1. Valve clearance cold should be:

    Intake: 0.006-0.010 inch (0.15-0.25mm)
     
    Exhaust: 0.010-0.014 inch (0.25-0.35mm)
     

  2.  
  3. Adjust the valve clearance by using adjusting shims.
    1. Turn the equipment drive shaft so that the cam lobe for the valve to be adjusted faces up.
    2.  
    3. Usinga retaining tool (SST 09248-05410) or equivalent, press down the valve lifter and place SST 09248-05420 or equivalent, between the camshaft and the valve lifter. Remove SST 09248-55040.
    4.  
    5. Remove the adjusting shim with a small flat prying tool and a magnetic finger.
    6.  
    7. Determine the replacement adjusting shim size according to the following formula, or use the adjusting shim charts.
    8.  
    9. Using a micrometer, measure the thickness of the removed shim. Calculate the thickness of a new shim so that the valve clearance comes within the specified value.

      T: Thickness of the removed shim
       
      A: Measured valve clearance
       
      N: Thickness of the new shim
       

    10.  
    11. Intake: N=T+ (A-0.008 inch (0.20mm)
    12.  
    13. Exhaust: N=T+ (A-0.012 inch (0.30mm)
    14.  
    15. Install a new adjusting shim. Place it on the valve lifter. Using the SST 09248-05410, press down the valve lifter and remove SST 09248-05420.
    16.  
    17. Recheck the valve clearance.
    18.  

  4.  



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Fig. Fig. 5: Using tool (A), press down the valve lifter, then place tool (B) between the camshaft and the valve lifter



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Fig. Fig. 6: With the aid of a magnet and small flatbladed tool, remove the shim



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Fig. Fig. 7: A micrometer is used to measure the thickness of shims

  1. After adjustments have been made, remove the equipment drive shaft bolt and nut. If not removed, the bolt head will hit and damage the cooling fan.
  2.  
  3. Install the No. 1 cylinder head cover bolts in the sequence. Torque to 6 ft. lbs. (8 Nm).
  4.  
  5. Install the No. 2 cord clamp support plate and tighten the bolt to 3.7 ft. lbs. (5 Nm).
  6.  
  7. Connect the spark plug wires. Install the PCV hose.
  8.  
  9. Install the No. 2 cylinder head cover and tighten the bolts to 10 ft. lbs. (14 Nm).
    1. Install the right engine service hole cover and tighten the bolts to 10 ft. lbs. (14 Nm).
    2.  
    3. Install the jack holder, the jack and the tool bag.
    4.  
    5. Install the bolts holding the right front seat leg and tighten to 29 ft. lbs. (39 Nm).
    6.  
    7. Install the right front seat and tighten the bolts to 29 ft. lbs. (39 Nm).
    8.  
    9. Install the bolt holding the seat belt to the front floor panel and tighten to 31 ft. lbs. (42 Nm).
    10.  
    11. Install the scuff plate.
    12.  

  10.  



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Fig. Fig. 8: Adjusting shim chart for the intake valves



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Fig. Fig. 9: Adjusting shim chart for the exhaust valves

 
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