Exhaust System. Cadillac Concours 1997

For 1990-2009 cars

## Exhaust System Exhaust System

### Catalytic Converter

The catalytic converter, an emission control device, attaches to the gasoline engine exhaust system, in order to reduce hydrocarbon, carbon monoxide and nitrogen oxides (NOx) emissions. The converter utilizes a honeycomb-shaped network, coated with catalytic material containing platinum, palladium and rhodium. This catalytic material promotes the oxidation and reduction of the pollutants, as the exhaust gasses pass through the converter, en route to the tailpipe. The catalytic converter also contains a heated oxygen sensor, which is located at the converter outlet.

Notice: In order to avoid damage to the catalyst, use unleaded fuel only.

Unleaded gasoline reduces deposits in the combustion chamber and on spark plugs, which extends the engine oil life and prevents lead contamination of the catalyst. Should the catalyst become contaminated, it is rendered ineffective, and the warranty coverage on the emission system is void.

### Exhaust System Hangers

The front hanger bracket assembly attaches to the front of the intermediate pipe, and connects to the underbody, with two rubber O-ring-type hangers.

### On-Vehicle Service

The catalytic converter has a monolithic design, and is only serviceable as a complete unit. Although the catalytic converter, intermediate pipe, mufflers, and tailpipe install as a complete, welded assembly, the exhaust manifold pipe and the intermediate pipe may service separately from the muffler/tailpipe assembly. The resonator is serviced with the intermediate pipe and does not service separately.

### Exhaust System Alignment

The exhaust system hanger's design minimizes noise transfer through the hangers. Vibration and noise will transfer into the vehicle through contact with the body, or hanger restriction.

When the exhaust system is at operating temperature, the clamps and insulators should be vertical. The support brackets are horizontal.

If repositioning the pipes, heat may be used in front of the rear suspension. The support brackets should be horizontally positioned. Allow the pipes to cool, before touching them. DO NOT use an acetylene torch near the fuel tank.

After adjusting the hangers or repositioning the pipes, inspect the entire system for adequate clearance to the frame members and the floor pan (minimum 15 mm or 5/8 in). The clearance between the mufflers and the spare tire is 35 mm. Tighten all of the clamps, according to the specified torques. Clearance avoids the overheating of the floor pan and possible damage to the passenger compartment carpets. The weight of the exhaust system should evenly distribute across all of the brackets and hangers, as indicated by an equal deflection at each hanger.

Some vehicles may exhibit exhaust system misalignment, due to the improper installation of the rear pipe (Y-pipe). When the rear pipe installs low in the assembly, it can pull the exhaust system forward, hitting part of the body. It may also pull the exhaust system close, such that when the vehicle travels over a bump, the exhaust system will contact the body. In order to correct the condition, reinstall the rear pipe, and the exhaust system should move into proper alignment.

### Exhaust Component Replacement

The following five components service the exhaust system for this vehicle:

• | Exhaust Manifold pipe/Y-pipe

• | Catalytic Converter

• | Intermediate exhaust pipe/resonator and muffler/tailpipe assembly

• | Muffler and tailpipe assembly

• | Left muffler and tailpipe assembly

Remember the following when servicing this system:

• | When replacing the components, use theJ 29800 exhaust pipe cutter, or equivalent, to make all cuts.

• | Remove the remaining portions of the intermediate pipe, when installing a replacement intermediate pipe to an existing catalytic converter.