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 DEPOSITIf 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 DEPOSITWhite deposits indicate the engine is running too hot.
WHITE DEPOSITIf 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.
SYSTEMS
ENGINE WEAR
CORRECT OPERATION
READING THE SPARK PLUGS