The Exhaust System:
Exhaust System Inspection
Inspection procedures for exhaust systems are about the same regardless of which type of vehicle you are working on.
To inspect the exhaust system, you will depend mostly on your senses of sight, hearing, and feel. Start at either end of the exhaust system and work toward the opposite end, inspecting for leaks and for loose, missing, defective, and improperly positioned components.
Above all, don't operate the vehicle engine for more than a minute or two unless it is located in a well-ventilated area. Otherwise, you may become a victim of carbon monoxide poisoning. Also, watch out that you don't burn yourself on any of the hot exhaust system parts.
Exhaust gas leaks are the most serious problems. You must make sure that you find and make a note of all of them, regardless of how small they are. Bad leaks make a lot of noise, so you can easily locate the general area they are coming from. Small leaks can be heard if you momentarily plug the tailpipe outlet. This causes any leaks to make a hissing noise due to back pressure building up in the exhaust system. After you find the general area of the leak, hold your hand near the suspected leak. You can feel escaping gases striking your hand. Be careful that you don't get your hand too close and get burned.
Inspect the exhaust manifold for tightness and cracks. Look closely for black carbon deposits that indicate a leak. All heat deflectors and shields must be secure and properly positioned to protect nearby parts from the heat.
When inspecting the exhaust pipe, muffler, and tailpipe, pay particular attention to damage caused by rust and corrosion, as this is the main cause of these parts going bad. Often, a muffler may look good from the outside but may be rusted away on the inside. Bump the muffler several times with your hand. If it rattles on the inside, the baffles are rusted loose and the muffler needs to be replaced.
All parts must be held securely in proper position by the hangers and not allowed to bump or rattle against the vehicle body, frame, or power train parts. There must be ample space between all hot exhaust system parts and items such as electrical wiring, brake hoses, and fuel lines. Even without touching, the insulation on wiring can burn away, and fuel can boil in a line.
Any large dents in the muffler, exhaust pipe, or tailpipe will slow down the flow of escaping gases and reduce engine power. A muffler that is full of carbon deposits will also restrict gas flow. You cannot see this kind of restriction, but if you suspect it, connect a vacuum pressure gage to the intake manifold. If the exhaust system is restricted, the manifold vacuum will read normal when the engine is first started but will drop rapidly.
Repair of the exhaust system is almost always limited to the replacement of parts. Never attempt to remove parts while they are still hot. |