Infinity_QX4_1998-2003

Camshaft & Valve Lifters

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Inspection



Runout
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the camshafts.
  4.  
  5. Using a V-block on a precise flat table, support the No. 2 and 4 journals of the camshaft.
    NOTE
    Do not support journal No. 1 as it has a different diameter than the other locations.

  6.  
  7. Set the dial indicator to No. 3 journal.
  8.  
  9. Turn the camshaft to one direction by hand and measure the camshaft runout.
  10.  
  11. Runout should measure less than 0.0008 inches (0.02 mm) and no more than 0.0020 inches (0.05 mm).
  12.  
  13. Camshaft should be replaced if it exceeds the limit.
  14.  

Cam Height
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the camshafts.
  4.  
  5. Measure the cam height with a micrometer.
  6.  
  7. The intake camshaft should measure between 1.7900 - 1.7974 inches (45.465 - 45.655 mm) and not less than 1.7821 inches (45.265 mm).
  8.  
  9. The exhaust camshaft should measure between 1.7746 - 1.7821 inches (45.075 - 45.265 mm) and not less than 1.7667 inches (44.875 mm).
  10.  
  11. Camshaft should be replaced if it exceeds the limit.
  12.  

Journal Oil Clearance
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the camshafts.
  4.  
  5. Measure the outer diameter of camshaft journal with micrometer and record the result.
  6.  
  7. Reinstall the camshaft bearing caps in accordance to the installation procedure.
  8.  
  9. Measure the inner diameter of the camshaft bracket (A) with a bore gauge and record the result.
  10.  
  11. Subtract the camshaft journal diameter from the camshaft bracket inner diameter. No. 1 journal should measure between 0.0018 - 0.0034 inches (0.045 - 0.086 mm). Nos. 2, 3 and 4 journals should be between 0.0014 - 0.0030 inches (0.035 - 0.076 mm). If any clearance measurement is more than 0.0059 inches (0.15 mm), the camshaft or cylinder (or both) needs to be replaced.
    NOTE
    The camshaft bracket cannot be replaced as an individual part, because it is machined together with the cylinder head. The entire cylinder head assembly must be replaced.



    Click image to see an enlarged view

    Fig. Measuring the journal bore for oil clearance

  12.  

End Play
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Install a dial indicator in the thrust direction on the front end of the camshaft. Measure the end play of the dial indicator when the camshaft is moved back and forth. The dial indicator should measure between 0.0045 - 0.0074 inches (0.115 - 0.188 mm) and not exceed 0.0094 inches (0.24 mm).
  4.  
  5. Measure the No. 1 journal as shown. The distance (A) should be 1.0827 - 1.0846 inches (27.500 - 27.548 mm).
  6.  
  7. Measure the No. 1 journal bearing as shown. The distance (B) should be 1.0772 - 1.0781 inches (27.360 - 27.385 mm).
  8.  
  9. Replace either the camshaft or cylinder head assembly if the measurement is exceeded.

    Click image to see an enlarged view

    Fig. Measuring for camshaft endplay

  10.  

Removal & Installation



3.5L Engine

See the Cylinder Head Removal and Installation procedure.

3.3L Engine
  1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
  2.  
  3. Drain the cooling system.
  4.  
  5. Remove the or disconnect the following:
    NOTE
    Keep all valvetrain components in order for assembly.



    Negative battery cable
     
    Upper intake manifold
     
    Valve covers
     



    Rocker arm and shaft assemblies
     
    Valve lifter guide and valve lifters. Attach a wire to the top of the lifters so that they will not drop from the lifter guide.
     
    Radiator
     
    Accessory drive belts
     
    Front cover
     
    Timing belt. Refer to the Timing Belt unit repair section.
     
    Camshaft sprockets
     
    Camshaft seals
     
    Rear timing cover
     
    Distributor
     
    Cylinder head rear covers
     
    Camshaft locating plates
     
    Camshafts
     

  6.  

To install:

  1. Install or connect the following:

    Camshafts
     
    Camshaft locating plates. Tighten the bolts to 58 - 65 ft. lbs. (78 - 88 Nm).
     
    Cylinder head rear covers
     
    Distributor
     
    Rear timing cover
     
    Camshaft seals
     
    Camshaft sprockets. Tighten the bolts to 58 - 65 ft. lbs. (78 - 88 Nm).
     
    Timing belt
     
    Front cover
     
    Accessory drive belts
     
    Radiator
     
    Valve lifter guide and valve lifters
     
    Rocker arm and shaft assemblies. Tighten the bolts to 13 - 16 ft. lbs. (18 - 22 Nm).
     
    Valve covers
     
    Upper intake manifold
     
    Negative battery cable
     

  2.  
  3. Fill the cooling system.
  4.  
  5. Start the engine and check for leaks.
  6.  

 
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