GM Full Size Vans 1967-1986 Repair Guide

Exhaust Manifold

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REMOVAL & INSTALLATION



Inline Six Cylinder Engines

See Figure 1



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Fig. Fig. 1: Exhaust manifold tightening sequence on 1975 and later inline 6 cylinder engines

1974 and earlier inline six cylinder exhaust manifold removal and installation procedures are covered under the Intake Manifold procedure (both manifolds are a unit). 1975 and later inline six procedures are covered below.

  1. Disconnect and remove the air cleaner assembly, including the carburetor preheat tube.
  2.  
  3. Disconnect the exhaust pipe at the exhaust manifold. You will probably have to use a liquid rust penetrant to free the bolts.
  4.  
  5. Remove the engine oil dipstick bracket bolt.
  6.  
  7. Liberally coat the manifold nuts with a rust penetrating lubricant. Remove the exhaust manifold bolts and remove the manifold.
  8.  
  9. To install, mount the manifold on the cylinder head and start all bolts.
  10.  
  11. Torque the bolts to specification using the torque sequence illustrated. Complete the installation by reversing the removal procedure.
  12.  

Gasoline V6 and V8 Engines

See Figures 2, 3, 4 and 5



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Fig. Fig. 2: Before unfastening the manifold bolts, you must first straighten the tab locks



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Fig. Fig. 3: After unfastening the manifold bolts, remove the manifold



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Fig. Fig. 4: View of the plastic manifold retainers-gasoline V8 engines



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Fig. Fig. 5: Common gasoline V8 engine exhaust manifold with exhaust shrouds

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 car using a suitable tool. When installing the tab locks, bend the tabs against the sides of the bolt, not over the top of the bolt.

  1. Remove the air cleaner.
  2.  
  3. Remove the hot air shroud, (if so equipped).
  4.  
  5. Loosen the alternator and remove its lower bracket.
  6.  
  7. Jack up your van and support it with jackstands.
  8.  
  9. Disconnect the crossover pipe from both manifolds.
  10.  

On models with air conditioning it may be necessary to remove the compressor, and tie it out of the way. Do not disconnect the compressor lines.

  1. Remove the manifold bolts and remove the 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.  
  3. Installation is the reverse of removal.
  4.  

6.2L Diesel Engines

RIGHT SIDE
  1. Disconnect the batteries.
  2.  
  3. Jack up the truck and safely support it with jackstands.
  4.  
  5. Disconnect the exhaust pipe from the manifold flange and lower the truck.
  6.  
  7. Disconnect the glow plug wires.
  8.  
  9. Remove the air cleaner duct bracket.
  10.  
  11. Remove the glow plug wires.
  12.  
  13. Remove the manifold bolts and remove the manifold.
  14.  
  15. To install, reverse the above procedure and torque the bolts to 25 ft. lbs. (33 Nm).
  16.  

LEFT SIDE
  1. Disconnect the batteries.
  2.  
  3. Remove the dipstick tube nut, and remove the dipstick tube.
  4.  
  5. Disconnect the glow plug wires.
  6.  
  7. Jack up the truck and safely support it with jackstands.
  8.  
  9. Disconnect the exhaust pipe at the manifold flange.
  10.  
  11. Remove the manifold bolts. Remove the manifold from underneath the truck.
  12.  
  13. Reverse the above procedure to install. Start the manifold bolts while the truck is jacked up first. Torque the bolts to 25 ft. lbs. (33 Nm).
  14.  

 
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