Isuzu Ascender 2003-05

Exhaust Manifold

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Removal & Installation



4.2L Engines
  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Remove or disconnect the following:

    Negative battery cable
     

  4.  


NOTE
It will be easier if the vehicle is only supported to a height where underhood access is still possible, the vehicle may be left in position for the entire procedure. If the vehicle is raised too high for underhood access, it will have to lowered, raised and lowered again during the procedure.



Air cleaner resonator outlet duct
 
Transmission filler tube stud nut from the Air Injector Reactor (AIR) adapter and move the tube aside
 
Oil level indicator tube
 
Oxygen (O2) sensor from the exhaust manifold
 
4 manifold heat shield nuts and shield
 
Exhaust pipe bolts from the exhaust manifold
 
Exhaust manifold bolts, and manifold
 
Old gaskets and discard
 

To install:

  1. Using a putty knife, clean the gasket mounting surfaces. Inspect the exhaust manifold for distortion, cracks or damage; replace if necessary.
  2.  
  3. Apply a threadlock such as GM 12345493 to the threads of the manifold retainers prior to installation.
  4.  
  5. Install or connect the following:

    Exhaust manifold to the cylinder using a new gasket, then tighten the bolts, in 3 passes, in sequence, to 18 ft. lbs. (25 Nm)
     


    Click image to see an enlarged view

    Fig. Exhaust manifold bolt tightening sequence-4.2L engine

    Heat shield studs, if necessary, and tighten to 89 inch lbs. (10 Nm)
     
    O2sensor
     
    Exhaust manifold heat shield
     

  6.  


NOTE
Apply a suitable anti-seize compound to the exhaust manifold heat shield nuts prior to installation.



Heat shield nuts and tighten to 44 inch lbs. (5 Nm)
 
Exhaust pipe to the manifold with seal and retaining nuts. Tighten the nuts to 37 ft. lbs. (50 Nm).
 
Oil level indicator tube
 
Transmission filler tube back onto the AIR adapter block stud and secure with the nut. Tighten the bracket nut to 89 inch lbs. (10 Nm).
 
Air cleaner resonator outlet duct
 
Negative battery cable.
 

  1. Before servicing the vehicle, refer to the precautions section.
  2.  
  3. Remove or disconnect the following:
    NOTE
    It will be easier if the vehicle is only supported to a height where underhood access is still possible, the vehicle may be left in position for the entire procedure. If the vehicle is raised too high for underhood access, it will have to lowered, raised and lowered again during the procedure.



    Negative battery cable
     



    Air cleaner resonator outlet duct
     
    Transmission filler tube stud nut from the Air Injector Reactor (AIR) adapter and move the tube aside
     
    Oil level indicator tube
     
    Oxygen (O 2 ) sensor from the exhaust manifold
     
    4 manifold heat shield nuts and shield
     
    Exhaust pipe bolts from the exhaust manifold
     
    Exhaust manifold bolts, and manifold
     
    Old gaskets and discard
     

  4.  

To install:

  1. Using a putty knife, clean the gasket mounting surfaces. Inspect the exhaust manifold for distortion, cracks or damage; replace if necessary.
  2.  
  3. Apply a threadlock such as GM 12345493 to the threads of the manifold retainers prior to installation.
  4.  
  5. Install or connect the following:
    NOTE
    Apply a suitable anti-seize compound to the exhaust manifold heat shield nuts prior to installation.



    Exhaust manifold to the cylinder using a new gasket, then tighten the bolts, in 3 passes, in sequence, to 18 ft. lbs. (25 Nm).

    Click image to see an enlarged view

    Fig. Exhaust manifold bolt tightening sequence-4.2L engine

     
    Heat shield studs, if necessary, and tighten to 89 inch lbs. (10 Nm).
     
    O 2 sensor
     
    Exhaust manifold heat shield
     



    Heat shield nuts and tighten to 44 inch lbs. (5 Nm).
     
    Exhaust pipe to the manifold with seal and retaining nuts. Tighten the nuts to 37 ft. lbs. (50 Nm).
     
    Oil level indicator tube
     
    Transmission filler tube back onto the AIR adapter block stud and secure with the nut. Tighten the bracket nut to 89 inch lbs. (10 Nm).
     
    Air cleaner resonator outlet duct
     
    Negative battery cable.
     

  6.  

5.3L Engine
  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Remove or disconnect the following:

    Negative battery cable
     
    Spark plug wires from the spark plugs. Don-t disconnect the wires from the ignition coil unless necessary for clearance.
     
    Exhaust manifold bolts, manifold and gasket. Discard the gasket.
     
    Heat shield bolt and shield, if necessary
     

  4.  

To install:

  1. Apply a 0.2 inch (5mm) bead of threadlock GM P/N 12345493, or equivalent to the threads of the exhaust manifold bolts. Do NOT apply sealer to the first 3 threads of the bolts.
  2.  
  3. Install or connect the following:

    New exhaust manifold gasket
     
    Exhaust manifold
     
    Exhaust manifold bolts. Tighten in two passes. First to 11 ft. lbs. (15 Nm), then to 18 ft. lbs. (25 Nm) starting with the center bolts and working outward.
     

  4.  
  5. Bend over the exposed edge of the gasket at the rear of the cylinder head using a flat punch or equivalent tool.

    Heat shield and bolts, if removed. Torque the bolts to 80 inch lbs. (9 Nm).
     
    Spark plug wires to the spark plugs
     
    Negative battery cable
     

  6.  

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

    Negative battery cable
     
    Spark plug wires from the spark plugs. Don-t disconnect the wires from the ignition coil unless necessary for clearance.
     
    Exhaust manifold bolts, manifold and gasket. Discard the gasket.
     
    Heat shield bolt and shield, if necessary
     

  4.  

To install:

  1. Apply a 0.2 inch (5mm) bead of threadlock GM P/N 12345493, or equivalent to the threads of the exhaust manifold bolts. Do NOT apply sealer to the first 3 threads of the bolts.
  2.  
  3. Install or connect the following:

    New exhaust manifold gasket
     
    Exhaust manifold
     
    Exhaust manifold bolts. Tighten in two passes. First to 11 ft. lbs. (15 Nm), then to 18 ft. lbs. (25 Nm) starting with the center bolts and working outward.
     

  4.  
  5. Bend over the exposed edge of the gasket at the rear of the cylinder head using a flat punch or equivalent tool.

    Heat shield and bolts, if removed. Torque the bolts to 80 inch lbs. (9 Nm).
     
    Spark plug wires to the spark plugs
     
    Negative battery cable
     

  6.  

 
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