From a fully warmed-up engine may indicate the presence of engine coolant in the combustion chamber. Coolant is typically a water-antifreeze mixture which, when exposed to the high temperatures in the engine cylinders during combustion, forms a white, sweet-smelling smoke which comes out of the tailpipe. Continuous white smoke is a sign of a failed head gasket or a crack in the cylinder head, allowing the coolant to get into the combustion chamber. When white smoke appears, repairs must be made quickly or serious damage.
One of the main causes of white exhaust smoke and coolant loss is a cracked or warped cylinder head, a cracked engine block, or head gasket failure caused by overheating. A cracked head may allow coolant to leak into one or more cylinders or into the combustion chamber of the engine. Dirty coolant, a poorly maintained cooling system, a low coolant level, or a non-functioning cooling fan can cause engine overheating. In addition, engine wear can eventually cause the gaskets to lose their capacity to seal properly allowing internal coolant loss. Intake manifold gasket and head gasket failures are two of the most common sources of internal coolant loss caused by engine wear.