GM Astro/Safari 1985-1996 Repair Guide

Component Replacement

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See Figures 1, 2, 3, 4, 5, and 6 in Exhaust System

REMOVAL & INSTALLATION



Front Pipe

See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: A deep socket is usually VERY helpful when trying to loosen exhaust pipe studs

Most of the early models covered by this guide and some of the late-model or Canada emission vehicles utilize a front exhaust pipe to convey gases from the manifolds to the converter or muffler (again, depending on the emission package). Certain California emission and late-model vehicles utilize a close-mount catalytic converter where the front pipe is part of the converter assembly.

  1. Raise and support the front of the vehicle safely using jackstands.
  2.  
  3. Remove the front pipe(s)-to-manifold(s) nuts and separate (pry, if necessary) the front pipe (ball joint) from the exhaust manifold(s).
  4.  
  5. At the catalytic converter, loosen the front pipe-to-converter clamp nuts, slide the clamp away from converter and separate the front pipe from the converter.
  6.  

Use a twisting motion to separate the front pipe-to-converter slip joint connection. If the front pipe cannot be removed from the catalytic converter, use a hammer (to loosen the connection) or wedge tool separate the connection.

  1. Inspect the pipe for holes, damage or deterioration; if necessary, replace the front pipe.
  2.  
  3. To install, lubricate the front pipe-to-manifold(s) studs/nuts and the front pipe-to-converter clamp threads, then tighten the clamps to 20 ft. lbs. (27 Nm).
  4.  
  5. Start the engine and check for exhaust leaks.
  6.  

Catalytic Converter

The catalytic converter is an emission control device added to the exhaust system to reduce the emission of hydrocarbon and carbon monoxide pollutants.

Most of the early models covered by this guide and some of the late-model or Canada emission vehicles utilize a front exhaust pipe to convey gases from the manifolds to the converter or muffler (again, depending on the emission package). Certain California emission and late-model vehicles utilize a close-mount catalytic converter where the front pipe is part of the converter assembly.

Without Integral Front Pipe
  1. Raise and support the front of the vehicle on jackstands.
  2.  
  3. Remove the catalytic converter-to-muffler stud nuts and separate the muffler from the converter.
  4.  

The connection between the converter and the muffler is a ball joint type, which can be easily separated.

  1. Remove the catalytic converter-to-front pipe clamp nuts and move the clamp forward.
  2.  
  3. Remove the converter-to-mounting bracket bolts (if equipped), then twist the converter to separate it from the front pipe.
  4.  
  5. Inspect the condition of the catalytic converter for physical damage, replace it, if necessary.
  6.  

When installing the catalytic converter, be sure that it is installed with adequate clearance from the floor pan, to prevent overheating of the vehicle floor.

  1. To install, align the components and reverse the removal procedures; be careful not to damage the pipe sealing surfaces when tightening the retaining clamps. Tighten the clamps to 20 ft. lbs. (27 Nm).
  2.  
  3. Start the engine and check for exhaust leaks.
  4.  

With Integral Front Pipe

See Figures 2 and 3



Click image to see an enlarged view

Fig. Fig. 2: Exploded view of a converter pipe-to-manifold connection



Click image to see an enlarged view

Fig. Fig. 3: Catalytic converter pipe-to-exhaust manifold tightening sequence-1996 models

  1. Raise and support the front of the vehicle safely using jackstands.
  2.  
  3. Support the catalytic converter assembly to keep it from falling and becoming damaged when it is detached.
  4.  
  5. Disengage the oxygen sensor electrical connection. For 1996 vehicles, you have 4 oxygen sensors, so make sure the wiring to all of them has been disengaged. Remove the wiring from any necessary clips and reposition it out of the way.
  6.  
  7. If equipped with a slip-joint at the rear of the converter, remove the clamp and separate the pipe from the converter.
  8.  
  9. If equipped with a bolted flange-joint at the rear of the converter, remove the converter-to-muffler retaining nuts.
  10.  
  11. Remove the nuts from the exhaust manifold studs. If equipped, remove the collars from the exhaust manifold studs.
  12.  
  13. Separate the converter pipe from the muffler and the exhaust manifolds, then carefully lower the front of the converter pipe down and remove the assembly from the hanger. Rotate the assembly over the rear of the transmission crossmember and remove it from the vehicle.
  14.  


CAUTION
Be very careful not to damage the converter or the oxygen sensor(s).

  1. To install, align the components and reverse the removal procedures; be careful not to damage the pipe sealing surfaces when tightening the retainers. Tighten the exhaust manifold stud nuts to 15 ft. lbs. (20 Nm), except for on 1996 vehicles where the manifold stud nuts must be tightened to 18 ft. lbs. (24 Nm), using the proper sequence.
  2.  
  3. Either tighten the converter-to-muffler nuts to 30 ft. lbs. (40 Nm) or the converter rear slip-joint clamp to 27 ft. lbs. (37 Nm) for all except 1995 models which should be tightened to 44 ft. lbs. (60 Nm).
  4.  
  5. Start the engine and check for exhaust leaks.
  6.  

Muffler

The following procedure requires the use of GM Sealing Compound No. 1051249 or equivalent. When replacing the muffler, always replace the tail pipe.

  1. Refer to the Tail Pipe, Removal and Installation procedures in this section and remove the tail pipe from the vehicle.
  2.  
  3. Loosen and move the catalytic converter-to-muffler clamp or remove the catalytic converter-to-muffler flange bolts and separate the items.
  4.  
  5. Remove the muffler-to-mounting bracket bolts and lower the muffler from the vehicle.
  6.  
  7. To install, coat the slip joints with GM Sealing Compound No. 1051249 or equivalent and loosely install the components onto the vehicle.
  8.  
  9. After aligning the components, tighten the connecting bolts and clamps to 20 ft. lbs. (27 Nm).
  10.  

When torquing the exhaust system connectors, be careful not to tighten the pipe clamps too tightly, or deformation of the pipes may occur.

  1. Start the engine and check for exhaust leaks.
  2.  

Tail Pipe

The following procedure requires the use of GM Sealing Compound No. 1051249 or equivalent.

Normally, when the tail pipe requires replacement, the muffler should be replaced also.

  1. Raise and support the rear of the vehicle on jackstands.
  2.  
  3. Remove the tail pipe-to-muffler clamp, then slide the clamp rearward.
  4.  
  5. Remove the tail pipe-to-mounting bracket clamp.
  6.  
  7. Using a twisting motion, remove the tail pipe from the muffler.
  8.  

If removal of the tail pipe difficult, use a hammer to free the pipe from the muffler.

  1. Inspect the tail pipe for holes of physical damage.
  2.  
  3. To install, use a new tail pipe (if necessary), a new muffler (if necessary), apply GM Sealing Compound No. 1051249 or equivalent to the slip joint(s), lubricate the pipe clamp threads with engine oil, loosely assemble the exhaust system, then tighten the components to 20 ft. lbs. (27 Nm).
  4.  
  5. Start the engine and check for exhaust leaks.
  6.  

 
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