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Wednesday, July 30, 2014
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Blog Engine Service: How does Exhaust Smoke determine the type of Engine Repair?

Engine Service: How does Exhaust Smoke determine the type of Engine Repair?

Exhaust smoke coming from your vehicle’s tailpipe is not good news, but it doesn’t necessarily mean the engine needs rebuilding. It may mean a simple engine service may be required.  But first, you need to determine the color of the smoke.  The color of the exhaust smoke will let your auto mechanic know what type of engine repair is needed.

The three most common colors of smoke that you will see emitted through the tailpipe are:

White Smoke: Caused by water and/or antifreeze entering the cylinders in the engine, and trying to burn it with the fuel.  The cylinder is where the fuel and air mixture are being compressed and burned. There are special gaskets to keep antifreeze from entering the cylinder area. However, the engine probably overheated and a head gasket failed due to excessive heat, thus allowing antifreeze to enter the cylinder. Any amount of antifreeze or water that enters this area will produce steam.  If your vehicle’s exhaust smoke is white, then an engine repair will probably consist of replacing the head gasket.

Blue Smoke: Caused by oil entering the cylinder area and being burned along with the fuel-air mixture.  Just a small drop of oil leaking into the cylinder can produce blue smoke. The car has many seals, gaskets, and O-rings that are designed to keep oil from entering the cylinder. One of them has failed. If too much oil leaks into the cylinder and fouls the spark plug, it will cause a misfire in that cylinder. If your vehicle’s exhaust is emitting blue smoke, then an engine repair will most likely consist of replacing some or all of the seals, gaskets and O-rings.

Black Smoke:  Caused by excess fuel that has entered the cylinder area and cannot be burned completely. Another term for excess fuel is "running rich."   Some of the causes of excess fuel could be a carburetor that is out of adjustment, a faulty fuel pump, a leaky fuel injector, or a faulty computer or sensor.  If your vehicle’s exhaust is emitting black smoke, schedule an appoint for an engine service to inspect the components listed above.

Need professional advice to determine what type of engine service your vehicle needs? Contact our ASE Certified Technicians at Excel Auto & Tire Service.  We will be happy to help you with any of your car problems.  Check our website at for the location closest to you.  Our 2 auto shops in the Twin Cities area are conveniently located in Eagan, MN and Spring Lake Park, MN.

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