My new-to-us (and our first Volvo) 740 Turbo has been smoking at the exhaust pipe when the engine's cold. I took the car to our local Volvo specialist, who said the smoke was caused by oil. He drove the car and said it seemed fine, but noticed some uncharacteristic "piston-knock." His opinion is that the oil could be coming from either the valve guides, bored out cylinders, or oil in the intercooler (It's a new Turbo in a car w/ 86,000 miles). He said that, as long as I check the oil regularly and keep the level where it should be, there's no reason to think that the car won't live a normal life. Sound reasonable? Any suggestions? Thanks!

Kevin:

I wouldn't totally rule out the turbocharger. I had the same symptoms in my '84, ie puffy white smoke at idle, and it was the turbo( I know because it didn't smoke until I had installed a supposedly good junkyard turbo, and it stopped as soon as I put my older unit back on.) It probably smoked even when warm, but the catalytic converter cleaned it up when hot. Smoke at idle is a sign of a worn turbo, at least according to my understanding. But as the valve stem oil seals are easier and cheaper (part:$25 from the dealer) than the turbo, you should probably start there. If you need the timing belt replaced (every 50K miles), that would be a good time to do the valve seals as much of the labor is redundant on the two jobs.

If it only smokes when starting cold, and when this occurs only smokes for a short time, then its likely to be oil dripping down into the cylinders due to worn valve guide seals. Like the mechanic said, it should run fine if you take care of it, but if it's just the seals, they aren't too difficult to replace yourself, so you might as well do it. Not a cause of immediate concern but I'd keep an eye out for more smoke on cold startup over time or even smoke while running normally.

Sounds reasonable. Have you checked the turbo intake hoses. Could cause some ping if the mixture isn't right. Also look under the engine in the exhaust side and see if you have oil leaking on the exhaust. Maybe the oil return line or oil cooler line are leaking and allowing it to leak. Valve guides are a good guess if nothing external.