EXHAUST SYSTEM

Your car's exhaust system has two functions. One is to carry away the poisonous, lethal gases from the passenger compartment, the other, to muffle the sound of the engine. If a leak develops anywhere in the system, fumes drifting upward through holes and crevices in the car's underbody and into the passenger compartment can make the people in the car sick. If a leak develops when you are on the road, drive with all the windows open until you can get it repaired.

Unfortunately, there is often little warning that your car's exhaust system is damaged. The first indication of danger may be the feeling of sickness caused by escaping carbon monoxide. If the muffler has developed a leak, you will hear a loud roaring noise, but the muffler is only one component of the exhaust system, and damage in the others can be silent. Periodic checks of the exhaust system, are, therefore, a must. By inspecting it every six months, you can spot weakened or damaged parts and loose connections, so that correc-tions can be made before problems develop.
The exhaust system starts at the exhaust manifold. From the engine compartment or from beneath the car, examine the joint connecting the exhaust pipe to the exhaust manifold. The presence of white powdery deposits on the connection means that the exhaust mani-fold/exhaust pipe flange gasket is leaking, or that the bolts are loose.

Start the engine, then watch and listen to the exhaust manifold/exhaust pipe joint. If you see exhaust puffing through the joint and/or hear a popping sound, the gasket is defective or the bolts are loose. Turn off the engine. From beneath the car, look carefully at every part of the exhaust system for cracks, holes, extreme rusting, and general damage. Working back from the exhaust manifold, check the exhaust pipe nearest the exhaust manifold; the muffler, tailpipe, clamps, and hangers for damage.

Many cars also have resonators, which act as second mufflers. A resonator is smaller than the main muffler and may be positioned to its front in the exhaust pipe, or behind it in the tailpipe. The resonator's job is to help the muffler further reduce engine noise. The resonator should be examined along with the rest of the exhaust system.

Most cars have a single exhaust system, but some with eight-cylin-der engines have two. In a dual system, one services the cylinders of the left bank of the engine, and the other services the cylinders of the right bank. Both systems, although separate, are virtually the same in make-up and layout, and both should be checked during an exhaust system examination.

Continue your examination by tapping each part, except the cata-lytic converter, with a wrench. A sound part will emit a ringing noise, whereas one which has failed or is about to fail will produce a dull thud. Look to see that hanger assemblies are intact. Broken assem-blies will cause an otherwise sound pipe or muffler to bang against another part of the car and become damaged. The final test is to start the engine and visually examine the entire exhaust system. If it has a previously undetected hole you will probably see exhaust smoke puffing from it.