A vehicle's exhaust color can reveal problems in the combustion chamber. Further inspection is required if the vehicle emits white smoke and continues to do so after startup. The engine's coolant enters the combustion chamber, vaporizes, and turns white when ignited.
This condition is often the result of an overheated engine. Overheating an engine can quickly warp a cylinder head and damage the head gasket. A crack in the cylinder head or engine block also causes this condition. This results in white exhaust billowing from the tailpipe.
The intake manifold gasket on some engines can leak, resulting in coolant entering the chamber and burning white. Excessive oil burning in the combustion chamber results in blue-gray-colored exhaust. Excessive fuel in the combustion chamber produces a rich air-fuel mixture and black-colored exhaust.