Exhaust smoke coming out of your car is never a good thing. Yet, for those who know how to recognize the signs, it can offer a valuable clue about just what is going wrong with your car. If you would like to know more about how to "read" your exhaust smoke, read on. This article will teach you about three common colors of exhaust smoke, and what each one means.
Blue exhaust smoke is generally a sign that the engine of your car is burning oil. This often corresponds to excessive wear in the valve guide oil seals--a problem that allows oil to leak upward out of the cylinder head and into either the intake or the exhaust manifold, where it then catches fire. Likewise, oil may escape due to certain types of damage to the cylinders themselves.
Blue exhaust smoke produced as the result of burning oil will often have the aroma of burning toast. In this case, your first move should always be to check your oil level, adding more as necessary. If your oil level drops too low as the result of a leak, serious damage to your engine will ensue. Even if this doesn't happen, burning oil may end up causing damage to your oxygen sensor or catalytic converter. Be sure to have a mechanic address the problem as soon as possible.
White smoke is a sign that your engine is burning either transmission fluid or coolant. If it's transmission oil, the smoke will likely smell of burnt oil; if coolant, it will have a sickly sweet aroma to it. The cause of burning transmission oil is usually that your engine is unintentionally drawing transmission fluid up through a vacuum hose. Burning coolant, on the other hand, is usually the result of a leak in the head gasket, or a cracked cylinder head.
Your first step should be to check both your car's coolant and transmission fluid levels, adding more as necessary. Then contact your nearest mechanic shop to schedule a diagnostic visit. They will perform a pressure test of your cooling system to determine if coolant is the cause of the smoke. If not, they will visually inspect the vacuum hoses for signs of transmission fluid inside.
Black smoke is commonly the sign that the fuel mixture in your engine is too "rich" -- in other words, that the ratio of fuel to air is skewed too far toward the fuel side. This may be the result of a wide variety of problems, everything from a stick choke, to a leaky float in your carburetor fuel bowl, to a dirty fuel filter. Seek a more professional diagnosis as soon as possible from a shop like R N S Service.