captain morgan

Hi. I recently bought an 2011 Q7 3.0l TDI. Had some coolant leaks and after water pump and some other components being replaced looks like we are no longer loosing coolant. It has however been brought to our attention by our mechanics that we have some positive pressure "SMOKE" coming from the dipstick and oil cap. Can that be something to do with a bad PCV valve or am I looking at an blown head casket. There is no water in the oil , no bubbles in the water . No white smoke from exhausts. No funny noises from the engine on start up or when running. Car goes like an bomb.
Please advise on the smoke from the oil cap.

dreadlocks

if the engine was hot this is normal, I just changed the oil on both my 3.0L TDI and my 2.0L FSI yesterday.. both had smoke come from the oil cap because both had been driven and were at operating temp when shut down and drained of fluid.

frqflyer

If dreadlocks says it's normal I would assume it is.

TDI is new engine for me, but on gassers I would not be thinking head gasket unless you see water in the oil and or coolant level dropping over time if you had that issue. On a gasser, and I would imagine would equally apply to diesel, was if I saw a considerable amount of smoke exiting the dip stick while running that I was getting blow-by on the rings, or a bad PCV or valve. Diesel runs at high compression and I assume as a result it gets more blow by on the rings. I've seen my brand new oil turn black after a short period, which I'm told is perfectly normal for diesels. If combustion, which it always does to some extent, it is entering the oil then it would not be odd to see it being expelled. Was it more like a vapor or was it smoking like a chimney?

dreadlocks

there will be alot of vaporized oil inside the crank and valvetrain on a hot engine, you take dip stick out and then pop off the oil cap and now you cracked open a sealed system, gave it an air intake (dipstick) and exhaust (oil cap), the convection will bring it out and you'll see the vapor wafting out of the engine for a few mins after cracking it open.

MAF cars throw a **** fit if there's any kinda leak, its pretty noticeable.. after refilling my wife's gasser with oil I started it to refill the oil filter before checking the level.. noticed engine was stuttering and it was running like garbage.. pushed the dip stick down the tube to check oil level and once it sealed off the engine smoothed out and ran perfectly.. pulled the dip stick out and it went back to running rough.. if the engine is running great, there is no reason to think anything is wrong just from seeing oil vapor escape.