Exhaust System

This Section covers the general exhaust system adjustments and service procedures.

Always refer to the Master Parts catalog for parts usage and interchangeability before replacing a component part of the exhaust system.

The exhaust system must be free of:

• Leaks.
• Binding.
• Grounding.
• Excessive vibrations.

These conditions are usually caused by loose, broken or misaligned:

• Clamps.
• Shields.
• Brackets.
• Pipes.

If any of these conditions exist, check the exhaust system components and alignment. Adjust or replace as necessary to maintain the specified clearances. Refer to the illustrations in this Section.

Replace these parts if they are damaged or badly corroded. Do not attempt to service:

• Brackets.
• Clamps.
• Insulators.

 WARNING: THE NORMAL OPERATING TEMPERATURE OF THE EXHAUST SYSTEM IS VERY HIGH. NEVER WORK AROUND OR ATTEMPT TO SERVICE ANY PART OF THE EXHAUST SYSTEM UNTIL IT HAS COOLED. USE SPECIAL CARE WHEN WORKING AROUND THE CATALYTIC CONVERTER. THESE UNITS HEAT TO A HIGH TEMPERATURE AFTER ONLY A SHORT PERIOD OF ENGINE OPERATION.

The factory-installed exhaust systems shown in the illustrations in this Section differ from the service replacement systems in the number of pieces used. When making a service replacement, refer to the Master Parts catalog for the current assemblies.

5.0L Engine

The exhaust system on eight-cylinder engines is equipped with:

• Dual converter and pipe (consisting of four catalysts).
• Two mufflers (5230) .
• Air inlet tube (5F235).

3.8L Engine

The exhaust system on six-cylinder engines is equipped with:

• Dual converter and pipe.
• One muffler .

Three-Way Catalytic Converter (TWC)

The three-way catalytic converter (5E212) , mounted in the engine exhaust stream:

• Plays a major role in the emission control system.
• Works as a gas reactor.
• Catalytic function is to speed up the heat-producing chemical reaction between components of the exhaust gases in order to reduce the air pollutants.
• Catalyst material inside the converter is made of a ceramic substrate that is coated with a high surface area alumina and impregnated with catalytically active platinum.
• The surface of the catalyst material is what plays a major role in the heat-producing chemical reaction.

Precautions

 WARNING: EXHAUST GASES CONTAIN CARBON MONOXIDE WHICH CAN BE HARMFUL TO HEALTH AND ARE POTENTIALLY LETHAL. EXHAUST SYSTEM LEAKS SHOULD BE REPAIRED IMMEDIATELY. NEVER OPERATE THE ENGINE IN ENCLOSED AREAS.

The following precautions must be observed when operating a vehicle equipped with a three-way catalytic converter .

 CAUTION: Leaded gas must not be used in a vehicle fitted with a catalytic converter—the lead will poison the catalyst.

If a vehicle is continually misfueled:

• The lead in the fuel will be deposited in the converter and completely blanket the catalyst.
• Lead combines chemically with platinum to "poison" the catalyst.
• Continuous use of leaded fuels can totally destroy the catalyst, and render the converter useless.
• This addition of lead to the converter can also solidify the catalyst, causing excessive back pressure in the exhaust system, possibly causing engine damage.

Extremely high temperatures of 1100°C (2012°F) or over, due to misfiring or over-rich fuel/air mixture will cause the ceramic base to sinter or burn, destroying the converter.

The catalytic converter has been designed to provide a long service life. No maintenance is necessary for the converter, however the following conditions must be avoided:

• Driving downhill with the gears engaged and the ignition switch (11572) OFF.
• Driving with misfiring engine.
• Running the engine continuously with a misfiring spark plug (12405) . When idling is unstable or when the engine lacks power, refer to the Diagnosis section of the appropriate group.
• Starting a warm engine by pushing the car. If the engine must be started by pushing the car, wait until the engine has cooled.
• Parking or stopping the vehicle over combustible material. If the vehicle is parked or stopped over combustible material such as dry grass, the material may be ignited by the high temperature of the three-way catalytic converter and muffler .