If your vehicle is showing thick white smoke coming from the exhaust, here are the most likely causes and the parts you'll need to fix each one.
The seal between the engine block and cylinder head has failed, allowing engine coolant to leak into the combustion chamber and vaporize into thick white smoke. This is often caused by engine overheating or an installation error, such as reusing old torque-to-yield head bolts or failing to properly machine the cylinder head during previous repairs.
On engines where coolant passages route through the intake manifold, a failed gasket can allow coolant to be drawn into the engine's air intake and burned. Improper torque sequence or failing to use RTV gasket maker in the corners during installation can cause premature failure.
If the vehicle is equipped with a water-cooled turbocharger, internal cracks or seal failures can allow coolant to leak directly into the hot exhaust turbine, instantly vaporizing it into thick white smoke.
Severe engine overheating or freezing (due to an improper water-to-antifreeze ratio) can physically crack the metal structure of the engine. This creates a permanent path for coolant to pour into the cylinders and exhaust.