Heavy white smoke sometimes what could it be?

This page might be able to help you out: http://repairpal.com/what-does-the-smoke-from-my-tail-pipe-mean Thick white smoke: White smoke may be produced when there is coolant or water in the combustion chamber; this is usually caused by a blown head gasket or cracked cylinder head. The coolant smoke will have a sweet smell and dissipate fairly quickly. This is generally accompanied by engine overheating and rough running. Thin white smoke: While the muffler and tail pipe warm up to proper operating temperature, condensation in the exhaust system will cause thin, white smoke. You may also notice condensation dripping from the drain hole in the muffler. This is normal and the smoke will dissipate very quickly. There are two lesser known causes for thin white smoke. One would be a severely leaking fuel injector (raw gasoline may be seen dripping from the tail pipe) and the engine will generally run rough. The other would be a transmission vacuum modulator leaking transmission fluid into the intake manifold. Transmission fluid will not have the sweet smell of coolant and dissipate more slowly. You may that notice the transmission is not shifting properly.