by Aaron Coates

Created on: August 08, 2011

Any time there is white smoke coming out of your car's exhaust system, it is an indication of a leak. This is not just any kind of leak, but a leak that is allowing either oil, coolant, or transmission fluid to get into the cylinders. The smoke is from the leaking substance not getting completely burned off like the air and fuel mixture does under normal operating conditions. In order to understand what is causing white smoke to come out of your car's exhaust pipes, you should become familiar with the different ways that these chemicals can enter the cylinders. Sometimes an engine that lets white smoke out of the exhaust system is completely normal because of condensation in the exhaust system being burned off.

Starting with the engine oil it should be common sense as to how it can be allowed to enter the combustion chambers in your engine, since oil is what lubricates all of the parts inside your engine. When oil burns, it leaves kind of a blue tint to the smoke, but it looks white to most people. After a few years of use, the rings that seal the pistons in your engine do not seal as good as they used to. There are scraper rings that are supposed to wipe the oil off the cylinder walls, and they get worn out also. When these rings wear out, there is a film of oil that stays on the cylinder wall, and when the combustion process happens, that oil gets burned away and is sent out the exhaust pipe along with the burnt air and fuel mixture. That is one way that oil enters the cylinders and cause white looking smoke to come out of the exhaust pipes. If this is the case, the engine will smoke the whole time it is running, and the exhaust will smell like burning oil. The only way to correct this situation is to re-seal the cylinders with new rings, which usually means a rebuild or an entire engine replacement.

One of the most basic ways this can happen is also very inexpensive to fix, and is completely normal. If the PCV valve is old it can leak and oil can be allowed to suck through the valve into the intake manifold. That is why you should change the PCV valve in your engine at least once a year if it needs it or not.

Another way that oil is allowed to enter the cylinders to be burned is through the valves. The valves in your engine go through machined surfaces that are called valve guides. These valve guides can also wear out, and let oil leak through them. That is the reason why there are seals on the top of the valves, to stop oil from dripping down the valve

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