Reading the Exhaust Tailpipe

*VERY EASY*

To determine the condition of the engine and discover potential problems, "read" the exhaust tailpipe. With your engine off and exhaust system cooled down, rub a cloth on the inside of the tailpipe. A properly operating and tuned gasoline engine should leave a light gray or light brown fine, powdery deposit on the inside surface.


GRAY/LIGHT BROWN DEPOSIT
GRAY/LIGHT BROWN DEPOSIT

If the deposit is some other color or texture, something is wrong.

For example, a black, sooty deposit means the fuel/air mixture is too rich.


BLACK, SOOTY DEPOSIT
BLACK, SOOTY DEPOSIT

White deposits indicate the engine is running too hot.


WHITE DEPOSIT
WHITE DEPOSIT

If the tailpipe deposit is a white or black powder, the cause of the problem is usually relatively easy to correct. However, if the deposit is black and oily, the engine may have worn components. This condition should be a cause of concern since it is usually more difficult to correct.

Reading the tailpipe should be the first step in determining the condition of your engine. If problems are revealed there, the spark plugs should be "read" for more insight.


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