GM Full-Size Trucks 1980-1987 Repair Guide

System Components




The exhaust manifold studs have to be heated, in most cases, before they can be removed. If the studs are badly rusted, there is a large possibility that they will break off inside the manifold. If this happens, the studs will have to be drilled out of the manifold, and the manifold retapped. Due to the cost of the equipment necessary to perform this procedure, it is recommended that it be done by a qualified mechanic.

Exhaust and Y-Pipe

Two studs hold the exhaust pipe to the manifold on four and in-line 6 cylinder engines. Four studs hold the Y-pipe on V6 and V8 models. A good quality lubricant, such as Liquid Wrench, should be applied to the studs before attempting to remove the nuts. Use a wire brush to remove some of the rust on the studs, this will make removing the nuts earlier. If the nuts are frozen to the studs, they will have to be heated to be removed. Before applying heat to the studs, make sure that you have removed the lubricant completely from the studs and nuts, as some lubricants are highly flammable. If the studs appear to be badly worn, and will probably break if the necessary force to free the nuts is applied, refer servicing to a qualified mechanic.

Catalytic Converter

The catalytic converter is connected to the exhaust or Y-pipe and the muffler by a muffler clamp. After removing the clamps, it may be necessary to use a hammer and chisel to separate the converter from the exhaust or Y-pipe and the muffler. Be careful not to damage any parts of the exhaust system that do not need to be replaced. Replace all clamps, nuts, bolts and straps. You do not want your new exhaust system to fall on the ground due to a worn clamp.


The muffler is attached to the catalytic converter by a muffler clamp, to the frame by two muffler hangers and to the tail pipe by a muffler clamp. After removing the clamps and hangers, it may be necessary to use a hammer and chisel to separate the muffler from the tail pipe.

Tail Pipe

The tail pipe is removed by loosening the nuts on the hanger that secure the pipe to the frame.


Exhaust System Sealer is to be applied to all slip joints before assembly.

When installing exhaust parts, make sure there is sufficient clearance between the hot exhaust parts and pipes and hoses that would be adversely affected by excessive heat.

Check complete exhaust system and nearby body areas and trunk lid for broken, damaged, missing, or mispositioned parts, open seams, holes, loose connections, or other deterioration which could permit exhaust fumes to seep into the passenger compartment. Any damaged areas must be corrected immediately. To help insure continued integrity, when replacing the muffler, resonator or pipes rearward of the muffler due to wear out, all parts rearward and including the muffler should be replaced.

When aligning the system, leave all bolts or nuts loose until all parts are properly aligned, then tighten, working from front to rear.

If any mispositioning, incorrect assembly, or failure of components in the area of the brake system pipes, hoses, or cylinders is observed, be sure to check for any brake damage that may have resulted from such a condition and correct as required. Make sure that exhaust system components have adequate clearance from the floor pan to avoid possible overheating of the floor pan and possible damage to the passenger compartment carpets. When jacking or lifting vehicle from frame side rails, be certain lift pads do not contact catalytic converter as damage to converter will result.

See Figures 1 and 2

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Fig. Fig. 1: Torque Specifications

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Fig. Fig. 2: Torque Specifications