Acura_MDX_2001-2006

Camshafts, Bearings, & Lifters

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Inspection



  1. Remove the cylinder head.
  2.  
  3. Remove the rocker arms.
  4.  
  5. Put the rocker shafts on the cylinder head, then tighten the bolts to the specified torque, as follows:
    1. Apply engine oil to the bolt threads and flange.
    2.  
    3. Tighten the 8 x 1.255mm bolts to 17 ft. lbs. (24 Nm).

      Click image to see an enlarged view

      Fig. Rocker shaft bolt tightening sequence

    4.  

  6.  
  7. Seat the camshaft by pushing it toward the rear of the cylinder head.
  8.  
  9. Zero the dial indicator against the end of the camshaft. Push the camshaft back and forth and read the end play. If the end play is beyond the service limit, replace the thrust cover and recheck. If it is still beyond the service limit, replace the camshaft:
    1. Standard (new): 0.002-0.008 in. (0.05-0.20mm)
    2.  
    3. Service Limit: 0.008 in. (0.20mm)

      Click image to see an enlarged view

      Fig. Zero the dial indicator against the end of the camshaft. Push the camshaft back and forth and read the end play

    4.  

  10.  
  11. Remove the camshaft thrust cover, then pull out the camshaft.
  12.  
  13. Wipe the camshaft clean, then inspect the lift ramps. Replace the camshaft if any lobes are pitted, scored or excessively worn.
  14.  
  15. Use a micrometer to measure the diameter of each camshaft journal.
  16.  
  17. Zero the gauge to the journal diameter.

    Click image to see an enlarged view

    Fig. Zero the gauge to the journal diameter

  18.  
  19. Clean the camshaft bearing surfaces in the cylinder head. Measure the inside diameter of each camshaft bearing surface, and check for an out-of-round condition:

    If the camshaft-to-holder clearance is within limits of 0.0020-0.0035 in. (0.050-0.089mm), go to step 11.
     
    If the camshaft-to-holder clearance is beyond the service limit of 0.006 in. (0.15mm), and the camshaft has been replaced, replace the cylinder head.
     
    If the camshaft-to-holder clearance is beyond the service limit of 0.006 in. (0.15mm), and the camshaft has not been replaced, go to step 10.

    Click image to see an enlarged view

    Fig. Measure the inside diameter of each camshaft bearing surface, and check for an out-of-round condition

     

  20.  
  21. Check total runout with the camshaft supported on V-blocks:

    If the total runout of the camshaft is within the service limit of 0.001 in. (0.03mm) max, replace the cylinder head.
     
    If the total runout is beyond the service limit 0.002 in. (0.04mm), replace the camshaft and recheck the oil clearance. If the oil clearance is still out of tolerance, replace the cylinder head.

    Click image to see an enlarged view

    Fig. Check total runout with the camshaft supported on V-blocks

     

  22.  
  23. Measure cam lobe height and compare with the following cam lobe height standard (new):

    PRI Intake: 1.3676 in. (34.737mm)
     
    MID Intake: 1.4348 in. (36.445mm)
     
    SEC Intake: 1.3748 in. (34.919mm)
     
    Exhaust: 1.4302 in. (36.326mm)

    Click image to see an enlarged view

    Fig. Measure cam lobe height

     

  24.  

Removal & Installation



2003-06 Models
Front
  1. Before servicing the vehicle, refer to the precautions section.
  2.  
  3. Remove or disconnect the following:

    Negative and positive battery cables
     
    Battery
     

  4.  
  5. Drain the coolant.

    Upper radiator hose
     
    Exhaust Gas Recirculation (EGR) vale
     
    Timing belt
     
    Rocker arm assembly
     
    Front camshaft pulley
     
    Thrust plate and camshaft
     

  6.  

To install:

  1. Install or connect the following:

    Camshaft using a new O-ring. Tighten the thrust plate to 16 ft. lbs. (22 Nm).
     
    Front camshaft pulley
     
    Rocker arm assembly
     
    Timing belt
     
    Exhaust Gas Recirculation (EGR) vale
     
    Battery
     
    Positive, then negative battery cables
     

  2.  
  3. Fill the cooling system.

    Camshaft

    Click image to see an enlarged view

    Fig. Front camshaft assembly-2003-06 models



    Click image to see an enlarged view

    Fig. Rocker arm shaft loosening sequence-2003-06 models



    Click image to see an enlarged view

    Fig. Rocker shaft tightening sequence-2003-05 models

     

  4.  
  5. Start the engine and check for leaks.
  6.  

Rear
  1. Before servicing the vehicle, refer to the precautions section.
  2.  
  3. Drain the cooling system.
  4.  
  5. Relieve the fuel system pressure.
  6.  
  7. Remove or disconnect the following:

    Negative battery cable
     
    Under-hood fuse box
     
    Fuel feed hose
     
    Nuts securing the fuel line

    Click image to see an enlarged view

    Fig. Remove the nuts attaching the fuel line when removing the rear camshaft-2003-06 models

     
    Brake lines from the master cylinder
     
    Timing belt
     
    Rocker arm assembly
     
    Rear camshaft pulley
     
    Thrust plate and camshaft
     

  8.  

To install:

  1. Install or connect the following:

    Camshaft using a new O-ring. Tighten the thrust plate to 16 ft. lbs. (22 Nm).
     
    Rear camshaft pulley
     
    Rocker arm assembly
     
    Timing belt
     
    Brake lines to the master cylinder
     
    Nuts securing the fuel line
     
    Fuel feed hose
     
    Under-hood fuse box
     
    Negative battery cable
     

  2.  

2001-02 Models
  1. Before servicing the vehicle, refer to the precautions section.
  2.  
  3. Remove or disconnect the following:

    Negative battery cable
     
    Air intake tube
     
    Accessory drive belts
     
    Front cover
     
    Timing belt
     
    Camshaft sprockets
     
    Timing belt rear covers
     
    Ignition coil covers
     
    Intake manifold cover
     
    Intake manifold
     
    Valve cover
     
    Rocker arms and shaft assembly
     
    Camshaft thrust cover
     
    Camshaft

    Click image to see an enlarged view

    Fig. Rocker arm shaft loosening sequence-2001-02 models

     

  4.  

To install:

Click image to see an enlarged view

Fig. Rocker shaft tightening sequence-2001-02 models


NOTE
Use new O-rings, seals and gaskets when installing the camshaft.

  1. Install or connect the following:

    Camshaft
     
    Camshaft thrust cover. Tighten the bolts to 16 ft. lbs. (22 Nm).
     
    Rocker arms and shaft assembly
     
    Valve cover
     
    Intake manifold
     
    Intake manifold cover
     
    Ignition coil covers
     
    Timing belt rear covers
     
    Camshaft sprockets. Tighten the bolts to 67 ft. lbs. (90 Nm).
     
    Timing belt
     
    Front cover
     
    Accessory drive belts
     
    Air intake tube
     
    Negative battery cable
     

  2.  
  3. Start the engine and check for leaks.
  4.  

 
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