If your vehicle is showing thick, sweet-smelling white smoke coming from the exhaust tailpipe, here are the most likely causes and the parts you'll need to fix each one.
The head gasket seals the engine block to the cylinder head. When it fails, engine coolant leaks into the combustion cylinders and burns, creating the thick, sweet-smelling white steam you see from the exhaust.
On many V-style engines, coolant flows through the intake manifold. A failed intake gasket can allow coolant to be sucked directly into the engine's air intake and burned in the cylinders.
If the engine had recent top-end work, failing to properly clean the mating surfaces, reusing old stretch bolts, or incorrectly torquing the head bolts will cause the new gasket to leak coolant immediately.
On turbocharged vehicles with water-cooled turbos, an internal seal failure can dump coolant directly into the hot exhaust turbine, instantly vaporizing it into thick white smoke.
Severe engine overheating or freezing without proper antifreeze can cause the metal cylinder head or engine block to crack, creating a permanent path for coolant to enter the combustion chamber.