Hi i have a volvo v70 .xc 5cyl turbo. On exalarasion ther is no smoke at the exoust under down hill compresion no smoke only exelarasion after down hill wite smoke and then it is gone

SOURCE: Hi wite smoke from the exoust wen under compresion and then exalarate it is gone . have done the rings ,velve stem seals and turbo kit and stil smoking .

It is common to see white exhaust smoke when first starting a car, especially on cooler days. This is generally steam caused by condensation. As the engine warms up and the condensation dissipates the white exhaust smoke (steam) is no longer seen. If you still see white smoke when the engine is warmed up then you probably have coolant leaking into the combustion chamber. Possible causes are warped head, blown head gasket or cracked block. Do you have unexplained coolant loss?
Good luck.