GM S-Series Pick-ups and SUV's 1994-1999 Repair Guide

Exhaust Manifold

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CAUTION
ALWAYS use extreme caution when working around the exhaust system. Make sure the engine has had time to thoroughly cool or personal injury from exhaust system burns may occur. Also, be sure to wear safety goggles when working on exhaust parts and they are likely to rust and loose particle will be falling from them during the procedure.

REMOVAL & INSTALLATION



2.2L Engine

See Figures 1 through 8



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Fig. Fig. 1: View of the exhaust manifold and related components-2.2L engine

  1. Disconnect the negative battery cable, then remove the air cleaner and duct work.
  2.  
  3. Unplug the oxygen sensor electrical connection. If the manifold or sensor is to be replaced, remove the sensor.
  4.  
  5. Remove the drive belt.
  6.  
  7. Raise the vehicle, support it with jackstands and disconnect the exhaust pipe from the manifold.
  8.  
  9. Unfasten the nut that attaches the oil fill tube assembly to the manifold and if necessary, remove the pipe.
  10.  
  11. If necessary, remove the heater hose brace.
  12.  
  13. If applicable, remove the power steering pump pencil brace and the heater hose brace and set the pump aside.
  14.  
  15. If applicable, remove the A/C compressor pencil and rear brace and set the compressor aside without disconnecting the lines.
  16.  
  17. Loosen and remove the exhaust manifold retaining nuts, then remove the manifold from the engine.
  18.  



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Fig. Fig. 2: Unfasten the nut that attaches the oil fill tube assembly to the manifold stud



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Fig. Fig. 3: Unfasten the nut that attaches the A/C compressor pencil brace (1) and the power steering pump and heater hose pencil braces (2) to the exhaust manifold studs, then remove the braces from the rear of the compressor and pump



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Fig. Fig. 4: Remove the exhaust manifold nuts and studs



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Fig. Fig. 5: If equipped with A/C, move the compressor aside without disconnecting the lines and remove the exhaust manifold from the engine compartment



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Fig. Fig. 6: If equipped, remove the smaller gasket pieces first ...



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Fig. Fig. 7: ... then remove the main manifold gasket



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Fig. Fig. 8: The exhaust manifold attaches to the engine with nuts and studs at these locations

To install:
  1. Carefully clean the threads of the exhaust manifold retainers, then remove all remaining traces of gasket from the mating surfaces.
  2.  
  3. Install the manifold to the engine using a new gasket, then tighten the manifold nuts to 115 inch lbs. (13 Nm). Connect the pipe to the manifold and tighten the retainers.
  4.  
  5. If removed, install the A/C compressor pencil and rear brace.
  6.  
  7. If removed, install the power steering pump brace and the heater hose brace.
  8.  
  9. If removed, install the heater hose brace.
  10.  
  11. Install the oil fill tube assembly.
  12.  
  13. Either install the oxygen sensor or engage the wiring, as applicable. If the sensor or manifold was replaced, tighten the oxygen sensor to 31 ft. lbs. (42 Nm).
  14.  
  15. Install the drive belt.
  16.  
  17. Install the air cleaner and duct work.
  18.  
  19. Connect the negative battery cable.
  20.  

4.3L Engine
1994-95 Models

See Figures 9, 10 and 11



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Fig. Fig. 9: Unfasten the exhaust manifold retaining bolts and studs then ...



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Fig. Fig. 10: ... remove the bolts and studs



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Fig. Fig. 11: Remove the exhaust manifold from the engine

  1. Disconnect the negative battery cable, then raise and support the front of the vehicle safely using jackstands.
  2.  

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.

  1. Disconnect the exhaust pipe from the exhaust manifold.
  2.  
  3. If necessary for underhood access, remove the jackstands and lower the vehicle.
  4.  
  5. Tag and disconnect the spark plug wires from the plugs and from the retaining clips.
  6.  
  7. If removing the left side manifold:
    1. Remove the air cleaner with heat stove pipe and cold air intake pipe.
    2.  
    3. Remove the power steering/alternator rear bracket.
    4.  
    5. Check for sufficient clearance between the manifold and the intermediate steering shaft. On some models it will be necessary to disconnect the intermediate shaft from the steering gear in order to reposition the shaft for clearance.
    6.  

  8.  
  9. If necessary when removing the right side manifold, unbolt the A/C compressor and bracket, then position the assembly aside. DO NOT disconnect the lines or allow them to become kinked or otherwise damaged.
  10.  
  11. If necessary for the right side manifold, remove the spark plugs, dipstick tube and wiring.
  12.  
  13. Unbend the locktangs then unfasten the exhaust manifold retaining bolts, washers and tab washers.
  14.  
  15. Disengage the exhaust manifold, then remove and discard the old gaskets.
  16.  

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. Install the exhaust manifold to the cylinder using a new gasket, then tighten the exhaust manifold-to-cylinder head bolts to 26 ft. lbs. (36 Nm) on the center exhaust tube and to 20 ft. lbs. (28 Nm) on the front and rear exhaust tubes. Once the bolts are tightened, bend the tabs on the washers back over the heads of all bolts in order to lock them in position.
  4.  
  5. If removed on the right side, install the spark plugs, dipstick tube and wiring.
  6.  
  7. If unbolted, reposition and secure the A/C compressor and bracket assembly.
  8.  
  9. If the left manifold was removed:
    1. If unbolted, reconnect the intermediate shaft to the steering gear.
    2.  
    3. Install the power steering/alternator rear bracket.
    4.  
    5. Install the air cleaner along with the heat stove pipe and cold air intake pipe.
    6.  

  10.  
  11. Connect the spark plug wires to the retainer clips and to the plugs as noted during removal.
  12.  
  13. If lowered for underhood access, raise and support the front of the vehicle again using the jackstands.
  14.  
  15. Connect the exhaust pipe to the manifold.
  16.  
  17. Remove the jackstands and carefully lower the vehicle, then connect the negative battery cable.
  18.  

1996-99 MODELS

See Figures 12 and 13



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Fig. Fig. 12: View of the exhaust manifold heat shields-1996 4.3L engine



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Fig. Fig. 13: The exhaust manifold is retained by studs and nuts-1996 4.3L engine

  1. Disconnect the negative battery cable, then raise and support the front of the vehicle safely using jackstands.
  2.  

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.

  1. Disconnect the exhaust pipe from the exhaust manifold. It may be necessary to remove the tires to gain access to the rear manifold bolts.
  2.  
  3. If removing the right side manifold on 1999 and later models, unfasten the engine oil dipstick tube bolt.
  4.  
  5. Remove the EGR inlet pipe from the left side manifold, if necessary.
  6.  
  7. On 1998 and later models after removing the EGR inlet pipe, unplug the Engine Coolant Temperature (ECT) sensor electrical connection and remove the upper radiator support hose and nut.
  8.  
  9. If removing the left side manifold on 1999 and later models, remove the steering intermediate shaft.
  10.  
  11. If removing the left side manifold on 1999 and later models, remove the wheel house extension.
  12.  
  13. Tag and disconnect the spark plugs wires from the plugs.
  14.  
  15. If equipped, on 1999 and later models, unfasten the nuts attaching the secondary air injection pipe to the manifold, then remove the pipe and gasket.
  16.  
  17. Unbend the locktangs then remove the exhaust manifold retaining bolts, washers and tab washers. Remove the heat shields.
  18.  
  19. Remove the exhaust manifold and if equipped.
  20.  
  21. Remove and discard the old gaskets.
  22.  

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. On 1996 models, install the exhaust manifold to the cylinder using a new gasket, then tighten the bolts to 22 ft. lbs. (30 Nm). Once the bolts are tightened, bend the tabs on the washers back over the heads of all bolts in order to lock them in position.
  4.  
  5. On 1998 and later models, apply a threadlock such as GM 12345493 or its equivalent to the threads of the manifold retainers prior to installation.
  6.  
  7. On 1997-99 models, install the exhaust manifold to the cylinder using a new gasket, then tighten the center bolts to 11 ft. lbs. (15 Nm) and the front and rear manifold bolts to 22 ft. lbs. (30 Nm). Once the bolts are tightened, bend the tabs on the washers back over the heads of all bolts in order to lock them in position.
  8.  
  9. Attach the spark plug wires to the plugs.
  10.  
  11. If removed on 1999 and later models, install the fender wheelhouse extension and the tire assembly.
  12.  
  13. If removed on 1999 and later models, install the secondary air injection pipe with a NEW gasket to the manifold, tighten the nuts to 18 ft. lbs. (25 Nm).
  14.  
  15. If removed, install the EGR inlet pipe, attach the ECT sensor electrical connection and install the upper radiator hose support and nut.
  16.  
  17. If removed on 1999 and later models (left side manifold only), install the steering intermediate shaft.
  18.  
  19. If removed from the right side manifold on 1999 and later models, fasten the engine oil dipstick tube bolt to 106 inch lbs. (12 Nm).
  20.  
  21. Engage the exhaust pipe to the manifold and lower the vehicle.
  22.  
  23. Connect the negative battery cable.
  24.  

 
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