GM Full-Size Trucks 1988-1998 Repair Information

Combination Manifold

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REMOVAL & INSTALLATION



4.8L Engines

See Figure 1



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Fig. Fig. 1: Combination manifold-4.8L engines

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner.
  4.  
  5. Disconnect the throttle controls at the bellcrank.
  6.  
  7. Remove the carburetor.
  8.  
  9. Disconnect and label the fuel and vacuum lines from the manifold.
  10.  
  11. Remove the AIR pump and bracket.
  12.  
  13. Disconnect the PCV hose.
  14.  
  15. Disconnect the exhaust pipe.
  16.  
  17. Remove the manifold heat stove.
  18.  
  19. Remove the clamps, bolts and washers and remove the combination manifold.
  20.  
  21. Separate the manifolds by removing the bolts and nuts.
  22.  

To install:
  1. Clean the mating surfaces.
  2.  
  3. Clean the stud threads.
  4.  
  5. Assemble the manifolds with a new gasket and leave the nuts finger-tight.
  6.  
  7. Install a new gasket over the manifold studs on the cylinder head and install the manifold assembly.
  8.  
  9. Install the bolts, clamps and nuts.
  10.  

Always tighten the manifold-to-cylinder head bolts and nuts to 38 ft. lbs. (52 Nm) before tightening the manifold center bolts and nuts to 44 ft. lbs. (60 Nm).

  1. Install the manifold heat stove.
  2.  
  3. Connect the exhaust pipe.
  4.  
  5. Connect the PCV hose.
  6.  
  7. Install the AIR pump and bracket.
  8.  
  9. Connect the fuel and vacuum lines from the manifold.
  10.  
  11. Install the carburetor.
  12.  
  13. Connect the throttle controls at the bellcrank.
  14.  
  15. Install the air cleaner.
  16.  
  17. Connect the negative battery cable.
  18.  

 
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