Lesson 3
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.
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