Intermittent white smoke (940 turbo)

[tomvovlo]

Hi, this is my first post so i might ramble a bit. Basically I bought a 940 Wentworth a couple of weeks ago and it drives great apart from sometimes when sat at traffic lights or a junction a cloud of white smoke comes out of the exhaust. When moving it doesn't occur/is not visible but when stationary it can be quite a large amount. After i first noticed it i cleaned out the PCV system but it wasn't very dirty to start with. The problem is the engine appears to have high crankcase pressure (oil seeps out of filler cap even after new seal and tightening the tabs, smoke from dipstick tube, oil leak from turbo oil return which might be unrelated?) but i know the pcv is working correctly because if i remove the breather from the top of the oil trap the gasses are visibly puffing out.

This makes me thing that my turbo might be on the way out apart from the fact that performance is great. Also the smoking only occurs when the engine is hot, not even a hint of smoke when cold. If i give it a hard rev while idling (when hot) i can get a small puff of smoke to appear but always a couple of seconds after releasing the throttle almost like it dumps a little bit of oil straight into the exhaust (again makes me think turbo).

I've searched lots of forums but seem to read conflicting info so wondered if anyone could give me some sort of more conclusive diagnosis based on the symptoms described?

[Will M]

Could be headgasket related, is the coolant level dropping, are you having to top it up frequently.

[tomvovlo]

Thanks for the reply Will M. No the coolant level is not dropping and the smoke smells of oil.

[TonyS9]

If it was oil buring it would be blue. White smoke is usually water condensation and weather depandant.

I doubt its anything to do with the PVC, anyway check for vacuum by lifting the oil filler cap gently with your finger tips close to the point where it touches the neck. You will feel a slight pull if its working, with the cap open it will just puff, perfectly normal, the vacuum is generated by a small tube otherwise the engine would stall when you took the cap off with the extra unmetered air entering the system.

Smelling of oil sounds odd.

[czech240]

White smoke could indicate unburnt fuel....

How is the car on start up? Whats the oil level like?

If the FPR is on its way out it could be letting fuel by...which may find it way into the exhaust....

My FPR let go completely and filled the intake and oil with petrol(nearly 7 litres came out when I changed it!). Lots of white smoke until it all burned off.... Just an idea... Hence checking the oil level!! :-)

[tomvovlo]

I changed the oil the other day after cleaning the PCV and have been checking it since and it hasn't changed but it i assumed it would only need to burn a little to cause smoke. also the smoke looks white but might be slightly blue it's hard to tell. I read that oil getting through the turbo and burning in the exhaust would cause white smoke rather than blue anyway. I had tried the filler cap test before i cleaned the pcv and it was dancing around when left loose but it still does this now (only to a lesser extent).