Exhaust system designs vary according to the engine designation and the intended use of the vehicle.
The exhaust pipe(s), muffler(s), and tailpipe(s) are standard equipment. The exhaust system uses a ball-joint coupling that secures the exhaust pipe to the engine manifold. The ball-joint allows angular movement for exhaust system alignment.
Other connections on the gasoline engine use a flat flange and gasket. The diesel engine uses a slip-joint coupling design with a clamp and U-bolt.
Hangers attached to the frame members suspend the exhaust system. These hangers allow some exhaust system movement, and they minimize the transfer of noise and vibration into the vehicle.
The catalytic converter is an emission control device which is added to the engine exhaust system. The catalytic converter reduces hydrocarbon, carbon monoxide and nitrogen oxide pollutants from the exhaust gases.
Heat shields protect the vehicle and the environment from the high temperatures produced by the exhaust system, especially the catalytic converter.
Notice: In order to avoid damage to the catalyst, use unleaded fuel only.
Vehicles with Light Duty Emissions (vehicles below 8,600 lb GVW) use a close-couple catalytic converter. The converter is part of the Y-pipe. The converter attaches forward to the flat flange.
Vehicles with Heavy Duty Emissions (vehicles above 8,600 lb GVW) use a three-way catalytic converter. One converter is part of the Y-pipe assembly and attaches in front of the flat flange. The second converter is part of the muffler assembly and mounts behind the flat flange.
An oxidizing catalytic converter is added to the diesel exhaust system. The oxidizing catalytic converter reduces smoke (particulates). The oxidizing catalytic converter operates at a normal exhaust system temperature. There is no significant temperature increase as a result of particulate oxidation.
The catalyst in the oxidizing converter is not serviceable.
Individual exhaust system replacement components will vary in regard to body/chassis and engine designation.
Removing Exhaust Parts
Dirt and corrosion will make the removal of exhaust components difficult. Apply a penetrating oil on the threads of the U-bolt assists before removing the components.
Installing Exhaust Parts
Important: Apply GM P/N 9985020 or equivalent to all the slip-joint connections.
Always use a new seal and nuts to install the exhaust pipe to the engine manifold. Clean the engine manifold stud threads with a wire brush before installing the new nuts.Check for correct alignment before installing a new exhaust pipe, muffler or tailpipe on any model. The misalignment of these parts usually causes rattles and noise vibrations in the exhaust system. Follow the following guidelines to align the system:
| • | Leave the nuts and bolts loose. |
| • | Align all of the parts correctly. |
| • | Tighten the nuts and the bolts from the front to the rear. |
In order to maintain exhaust system alignment, replace the following components if they are damaged:
| • | System hangers |
| • | Hanger brackets |
| • | Clamps |
