GM Full-Size Trucks 1988-1998 Repair Information

Exhaust Manifold

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For the 4.8L engine, please refer to the Combination Manifold procedure.

REMOVAL & INSTALLATION



4.3L Engines

See Figure 1

On some engines, 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 truck 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.



Click image to see an enlarged view

Fig. Fig. 1: Exhaust manifold-4.3L engines

1988-94 MODELS
  1. Disconnect the negative battery cable. Remove the air cleaner assembly.
  2.  
  3. Raise the vehicle and support it with jackstands.
  4.  
  5. Remove the hot air shroud, (if so equipped). Disconnect the exhaust pipe at the manifold.
  6.  
  7. Lower the truck.
  8.  
  9. Disconnect the oxygen sensor wire on the left side manifold. Do not remove the sensor unless you intend to replace it.
  10.  
  11. Disconnect the rear power steering pump bracket at the left manifold.
  12.  
  13. Remove the heat stove pipe on the right side manifold.
  14.  
  15. Remove the AIR hose at the check valve.
  16.  
  17. 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.
  18.  

To install:
  1. Clean both the manifold and cylinder block mating surfaces and install the manifold. Install the flat washers and then the tab washers and insert the bolts. Tighten the two center bolts to 26 ft. lbs. (36 Nm); the outside bolts to 20 ft. lbs. (28 Nm) and then bend the tab washers against the bolt heads.
  2.  
  3. Install the AIR hose at the check valve.
  4.  
  5. Install the heat stove pipe on the right side manifold.
  6.  
  7. Connect the rear power steering pump bracket at the left manifold.
  8.  
  9. Connect the oxygen sensor wire on the left side manifold.
  10.  
  11. Raise the truck and support it with jackstands.
  12.  
  13. Connect the exhaust pipe at the manifold. Install the hot air shroud.
  14.  
  15. Lower the truck.
  16.  
  17. Install the air cleaner. Connect the negative battery cable.
  18.  

1995-98 MODELS
  1. Disconnect the negative battery cable.
  2.  
  3. Raise the vehicle and support it with jackstands.
  4.  
  5. Remove the hot air shroud, (if so equipped). Disconnect the exhaust pipe at the manifold.
  6.  
  7. Lower the truck.
  8.  
  9. If removing the left side manifold, remove the EGR inlet pipe.
  10.  
  11. Unfasten the manifold retainers and remove the manifold.
  12.  

To install:
  1. Clean the exhaust manifold mating surfaces to remove any gasket residue.
  2.  
  3. Install the manifold and tighten the retainers in the following sequence:

    Bolts on the center exhaust tube: 26 ft. lbs. (36 Nm)
     
    Bolts on the front and rear exhaust tubes: 20 ft. lbs. (28 Nm)
     

  4.  
  5. Bend the tab washers over the bolts.
  6.  
  7. If installing the left side manifold, install the EGR inlet pipe.
  8.  
  9. Raise the vehicle and support it with jackstands.
  10.  
  11. Install the exhaust pipe at the manifold.
  12.  
  13. Install the hot air shroud, If equipped.
  14.  
  15. Lower the vehicle.
  16.  
  17. Connect the negative battery cable.
  18.  

5.0L and 5.7L Engines

1988-95 models

See Figures 2, 3, 4, 5 and 6

On some engines, 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 truck 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. Disconnect the negative battery cable. Remove the air cleaner.
  2.  



Click image to see an enlarged view

Fig. Fig. 2: Exhaust manifold-1988-95 5.0L and 5.7L engines

  1. Raise the truck and support it with jackstands.
  2.  
  3. Remove the hot air shroud, (if so equipped). Disconnect the exhaust pipe at the manifold.
  4.  
  5. Lower the truck.
  6.  
  7. Disconnect the oxygen sensor wire on the left side manifold. Do not remove the sensor unless you intend to replace it.
  8.  
  9. Remove the AIR hose at the check valve.
  10.  
  11. Remove the heat stove pipe on the right side manifold.
  12.  
  13. Disconnect the rear power steering pump bracket at the left manifold.
  14.  
  15. Remove the dipstick tube bracket on the right manifold.
  16.  
  17. Remove the manifold bolts and remove the manifold(s). Some models have locktabs on the front and rear manifold bolts which must be removed before removing the bolts. These tabs can be bent with a drift pin or needle-nose pliers.
  18.  

To install:
  1. Clean both the manifold and cylinder block mating surfaces and install the manifold. Install the flat washers and then the tab washers and insert the bolts. Tighten the two center bolts to 26 ft. lbs. (36 Nm); the outside bolts to 20 ft. lbs. (28 Nm) and then bend the tab washers against the bolt heads.
  2.  
  3. Install the dipstick tube bracket on the right manifold.
  4.  
  5. Connect the rear power steering pump bracket at the left manifold.
  6.  
  7. Install the heat stove pipe on the right side manifold.
  8.  
  9. Install the AIR hose at the check valve.
  10.  
  11. Connect the oxygen sensor wire on the left side manifold.
  12.  
  13. Raise the truck and support it with jackstands.
  14.  
  15. Connect the exhaust pipe at the manifold. Install the hot air shroud.
  16.  
  17. Lower the truck.
  18.  
  19. Install the air cleaner. Connect the negative battery cable.
  20.  



Click image to see an enlarged view

Fig. Fig. 3: Remove the exhaust pipe from the manifold



Click image to see an enlarged view

Fig. Fig. 4: Use a pair of needle-nose pliers to bend back the locktabs on the exhaust manifold



Click image to see an enlarged view

Fig. Fig. 5: Loosen and remove the exhaust manifold bolts



Click image to see an enlarged view

Fig. Fig. 6: Remove the exhaust manifold

1996-98 models

See Figure 7

  1. Disconnect the negative battery cable.
  2.  
  3. Raise the vehicle and support it with jackstands.
  4.  
  5. Disconnect the exhaust pipe at the manifold.
  6.  
  7. Lower the truck.
  8.  
  9. If removing the left side manifold, remove the EGR inlet pipe.
  10.  
  11. Remove the engine oil level indicator bracket from the right side manifold.
  12.  
  13. Unfasten the manifold retainers and remove the manifold.
  14.  

To install:
  1. Clean the exhaust manifold mating surfaces to remove any gasket residue.
  2.  
  3. Install the manifold and tighten the retainers in the following sequence:

    First pass: 15 ft. lbs. (20 Nm)
     
    Final pass: 22 ft. lbs. (30 Nm)
     

  4.  
  5. Bend the tab washers over the bolts.
  6.  
  7. Install the engine oil indicator tube to the right side manifold.
  8.  
  9. If installing the left side manifold, install the EGR inlet pipe.
  10.  
  11. Raise the vehicle and support it with jackstands.
  12.  
  13. Install the exhaust pipe at the manifold.
  14.  
  15. Lower the vehicle.
  16.  
  17. Connect the negative battery cable.
  18.  



Click image to see an enlarged view

Fig. Fig. 7: Exhaust manifold mounting-1996-98 models

7.4L Engines
RIGHT SIDE-1988-95 models
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the heat stove pipe.
  4.  
  5. Remove the dipstick tube.
  6.  
  7. Disconnect the AIR hose at the check valve.
  8.  
  9. Remove the spark plugs.
  10.  
  11. Disconnect the exhaust pipe at the manifold.
  12.  
  13. Remove the manifold bolts and spark plug heat shields.
  14.  
  15. Remove the manifold.
  16.  

To install:
  1. Clean the mating surfaces.
  2.  
  3. Clean the stud threads.
  4.  
  5. Install the manifold and bolts. Tighten the bolts to 40 ft. lbs. (54 Nm) starting from the center bolts and working towards the outside.
  6.  
  7. Connect the exhaust pipe at the manifold.
  8.  
  9. Install the spark plugs.
  10.  
  11. Connect the AIR hose at the check valve.
  12.  
  13. Install the dipstick tube.
  14.  
  15. Install the heat stove pipe.
  16.  
  17. Connect the battery.
  18.  

LEFT SIDE-1988-95 models
  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the oxygen sensor wire.
  4.  
  5. Disconnect the AIR hose at the check valve.
  6.  
  7. Remove the spark plugs.
  8.  
  9. Disconnect the exhaust pipe at the manifold.
  10.  
  11. Remove the manifold bolts and spark plug heat shields.
  12.  
  13. Remove the manifold.
  14.  

To install:
  1. Clean the mating surfaces.
  2.  
  3. Clean the stud threads.
  4.  
  5. Install the manifold and bolts. Tighten the bolts to 40 ft. lbs. (54 Nm) starting from the center bolts and working towards the outside.
  6.  
  7. Connect the exhaust pipe at the manifold.
  8.  
  9. Install the spark plugs.
  10.  
  11. Connect the AIR hose at the check valve.
  12.  
  13. Connect the oxygen sensor wire.
  14.  
  15. Connect the battery.
  16.  

1996-98 models

See Figure 8

  1. Disconnect the negative battery cable.
  2.  
  3. If removing the right side manifold, remove the oil level indicator tube.
  4.  
  5. If removing the left side manifold, remove the EGR inlet pipe.
  6.  
  7. Remove the spark plugs.
  8.  
  9. Remove the exhaust pipe from the manifold.
  10.  
  11. Unfasten the heat shield nuts and remove the heat shield.
  12.  
  13. Unfasten the exhaust manifold retainers, then remove the manifold.
  14.  
  15. Clean any gasket material from the manifold mating surfaces, also clean the manifold mounting studs.
  16.  



Click image to see an enlarged view

Fig. Fig. 8: Exhaust manifold mounting-1997-98 7.4L engines

To install:
  1. Install the exhaust manifold and the manifold nuts. Tighten the nuts to 22 ft. lbs. (30 Nm).
  2.  
  3. Install the spa.
  4.  
  5. Install the heat shields and nuts. Tighten the nuts to 15 ft. lbs. (20 Nm).
  6.  
  7. Attach the exhaust pipe to the manifold.
  8.  
  9. If removed from the left side manifold, install the EGR inlet pipe.
  10.  
  11. If removed from the right side manifold, install the oil level indicator tube. Tighten the bolt to 40 ft. lbs. (54 Nm).
  12.  
  13. Connect the negative battery cable.
  14.  

6.2L and 6.5L Diesel Engines
RIGHT SIDE-1988-95 Models

See Figures 9 and 10

  1. Disconnect the batteries.
  2.  
  3. Jack up the vehicle and safely support it with jackstands.
  4.  



Click image to see an enlarged view

Fig. Fig. 9: Exhaust manifold (right side)-6.2L engines



Click image to see an enlarged view

Fig. Fig. 10: Exhaust manifold (right side)-6.5L engines

  1. Disconnect the exhaust pipe from the manifold flange and lower the truck.
  2.  
  3. Disconnect the glow plug wires.
  4.  
  5. Remove the air cleaner duct, box and if necessary the duct bracket.
  6.  
  7. Remove the glow plug wires.
  8.  
  9. Remove the turbocharger on the 6.5L, if equipped.
  10.  
  11. Remove the manifold bolts and remove the manifold.
  12.  

To install:
  1. Clean all mating surfaces and install the manifold. Tighten the bolts to 26 ft. lbs. (35 Nm).
  2.  
  3. Install the turbocharger on the 6.5L, if equipped.
  4.  
  5. Install the glow plugs.
  6.  
  7. Install the air cleaner, box duct and if removed, the duct bracket.
  8.  
  9. Connect the glow plug wires.
  10.  
  11. Raise the vehicle and support it with jackstands.
  12.  
  13. Connect the exhaust pipe to the manifold flange and lower the truck.
  14.  
  15. Connect the batteries.
  16.  

LEFT SIDE-1988-95 Models

See Figure 11

  1. Disconnect the batteries, negative cable first.
  2.  
  3. Remove the dipstick tube nut, and remove the dipstick tube.
  4.  



Click image to see an enlarged view

Fig. Fig. 11: Exhaust manifold (left side)-6.2L and 6.5L engines

  1. Disconnect the glow plug wires.
  2.  
  3. Raise the vehicle and safely support it with jackstands.
  4.  
  5. Disconnect the exhaust pipe at the manifold flange.
  6.  
  7. Remove the manifold bolts. Remove the manifold from underneath the truck.
  8.  

To install:
  1. Install the manifold and tighten the bolts to 25 ft. lbs. (35 Nm).
  2.  
  3. Connect the exhaust pipe to the manifold flange.
  4.  
  5. Lower the vehicle and connect the glow plug wires.
  6.  
  7. Install the dipstick tube and tighten the nut.
  8.  
  9. Connect the batteries, positive cable first.
  10.  

RIGHT SIDE-1996-98 Models
  1. Disconnect the batteries.
  2.  
  3. Remove the air cleaner duct and box.
  4.  
  5. Jack up the vehicle and safely support it with jackstands.
  6.  
  7. Disconnect the exhaust pipe from the manifold flange.
  8.  
  9. Disconnect the glow plug wires.
  10.  
  11. Remove the glow plug wires.
  12.  
  13. Lower the truck.
  14.  
  15. Remove the turbocharger.
  16.  
  17. Remove the glow plugs and their shields.
  18.  
  19. Unfasten the manifold bolts and remove the manifold.
  20.  

To install:
  1. Clean all mating surfaces and install the manifold. Tighten the bolts to 26 ft. lbs. (35 Nm).
  2.  
  3. Install the glow plugs and their shields.
  4.  
  5. Install the turbocharger.
  6.  
  7. Raise the truck and support it with safety stands.
  8.  
  9. Install the glow plug wires.
  10.  
  11. Connect the exhaust pipe to the manifold flange and lower the truck.
  12.  
  13. Install the air cleaner box and duct.
  14.  
  15. Connect the batteries.
  16.  

LEFT SIDE-1996-98 Models

See Figure 12

  1. Disconnect the batteries, negative cable first.
  2.  
  3. Raise the vehicle and safely support it with jackstands.
  4.  
  5. Remove the glow plugs.
  6.  
  7. Disconnect the exhaust pipe at the manifold flange.
  8.  
  9. Unfasten the manifold bolts. Remove the manifold from underneath the truck.
  10.  
  11. Clean the manifold mating surfaces.
  12.  

To install:


Click image to see an enlarged view

Fig. Fig. 12: Typical exhaust manifold mounting-1996-98 6.5L diesel engine

  1. Install the manifold and tighten the bolts to 25 ft. lbs. (35 Nm).
  2.  
  3. Connect the exhaust pipe to the manifold flange.
  4.  
  5. Lower the vehicle and install the glow plugs.
  6.  
  7. Connect the batteries, positive cable first.
  8.  

 
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