White smoke coming from the engine area can be caused by a couple different things.
|STEP 1||Turbo Failures: The turbo could be failing. What typical happens is that the seals in the turbocharger go bad. During this failure the turbo will usually puff smoke when coming to an idle or begin to smoke terribly when idling for long periods of time.|
|STEP 2||Head Gasket Leaking: The head gasket may be leaking into the combustion chamber(s) overnight which leads to white smoke coming from the exhaust (really steam) during cold start. Once the engine is warm this smoke will dissappear because it is actually burning the coolant from within the conbustion chamber. Head gasket failure between two cylinders is usually the problem. You can often determine if this is the problem by removing the spark plugs to see if any of the piston tops are silver which is an indication that the coolant being burned is cleaning the carbon from the piston top.|
|STEP 3||Valve guide/Seal Issues: Valve guide issues can cause the engine to smoke during startup. This is usually an indication that you either have work guides or valve stem seals which allow oil to leak past them once the engine is turned off. Rebuilding or replacing the cylinder head is the only cure.|
Thanks to john wilson for contributing to this FAQ!
I have a saab 93 20 ltr turbo the car was smoking very badly and saab reccomended a turbo change, so i changed the turbo but still the problem persisted, after removing the head for a rebuild i stripped it of both manifolds changed the valve seals and gasgets in fact i replaced everthing that would let oil leak into the bores while i had the inlet manifold off i noticed an oil port between the headand the manifold that nobody including the saab agents were aware of, in the inlet manifold is a tube that runs down to the throttle body and in that tube is a one way valve about 4 inches long, costs £4.00 this had failed causing engine oil to leak into the inlet manifold hence the white smoke.