GM Buick/Oldsmobile/Pontiac/Full-Size 1975-1990 Repair Guide

Exhaust Manifold

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REMOVAL & INSTALLATION



See Figures 1, 2, 3 and 4

Tab locks are used on the front and rear pairs of bolts on each exhaust manifold. When removing the bolts, straighten the tabs from beneath the vehicle using a suitable tool. When installing the tab locks, bend the tabs against the flats on the sides of the bolt, not over the top of the bolt.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner. Number and then disconnect the spark plug wires.
  4.  
  5. Remove the hot air shroud (if so equipped). If the vehicle has Early Fuel Evaporation (EFE), disconnect the vacuum hose, if it is in the way.
  6.  
  7. Loosen the alternator and remove its lower bracket. Disconnect the pipe for the Air Injection Reactor (AIR) system.
  8.  
  9. Raise the vehicle and support it with jackstands.
  10.  
  11. Disconnect the crossover pipe from both manifolds.
  12.  
  13. On models with air conditioning, especially on V8 engines when removing the left side manifold, it may be necessary to remove the compressor and tie it out of the way. On V8 engines, to remove the left manifold, loosen the compressor mounting bracket at the front of the head, remove the rear bracket, and then hang the compressor so you don't put strain on the refrigerant lines.
  14.  


CAUTION
Do not disconnect the compressor lines! This should only be done after the system is discharged by a trained technician with a recovery/recycling station.

  1. Remove the manifold bolts and remove the exhaust manifold(s). Some models have lock tabs on the front and rear manifold bolts which must be removed before removing the bolts. These tabs can be bent with a drift pin.
  2.  

To install:
  1. Install the manifold and bolts. Some models have lock tabs on the front and rear manifold bolts which must be bent over the flats of the bolts to prevent loosening. These tabs can be bent with a drift pin. Torque the bolts to specifications found in the Torque specifications chart in the beginning of this section.
  2.  
  3. On models with air conditioning, especially on V8 engines when installing the left side manifold, reinstall the compressor, tighten the belt and mounting bolts. DO NOT put strain on the refrigerant lines.
  4.  
  5. Raise the vehicle and support it with jackstands.
  6.  
  7. Connect the crossover pipe to both manifolds. Lower the vehicle.
  8.  
  9. Tighten the alternator and install its lower bracket. Connect the pipe for the Air Injection Reactor (AIR) system.
  10.  
  11. Install the hot air shroud (if so equipped). If the vehicle has Early Fuel Evaporation (EFE), connect the vacuum hose, if it was disconnected.
  12.  
  13. Install the air cleaner. Connect the spark plug wires.
  14.  
  15. Connect the negative battery cable, start the engine and check for exhaust leaks.
  16.  



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Fig. Fig. 1: Exhaust manifold and hot air shroud assembly



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Fig. Fig. 2: Removing the exhaust manifold attaching bolts



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Fig. Fig. 3: Removing the hot air shroud



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Fig. Fig. 4: Removing the exhaust manifold from the engine

 
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