BMW X6 2009 35d - Exhaust Smoking

[farhan]

Hi Guys,

I'm a newbie to the forum and I just wanted to ask if anyone knew about why my BMW X6 2009 is smoking. When I start the car it's ok, but when I move off I can see smoke coming out of the exhaust, as I start driving I cant see anything but then when I come to a standstill for example at lights, or sitting in traffic I can see the smoke clearly. It's not thick smoke but its not light either.

Would really appreciate some help in diagnosing the issue

Farhan

[X5Sport]

Definitely don't get it with mine.  Steam yes, but not smoke, even on a cold morning start.

Which engine, mileage...?

It is oil smoke or diesel smoke?  Oil tends to be blue, diesel white or black.

[farhan]

BMW X6 2009 35d, just dropped it into my cousins garage, they think it could be the turbo, apparently it's Ble smoke, when I'm driving I can't see it but when I'm sitting in traffic you can see a lot of smoke. Car will be diagnosed tomorrow so will find out more.

[farhan]

Garage thinks it's turbo....personally I don't think it's the turbo....the car is giving out blue smoke and you can blatantly smell the oil....I can now see the smoke when I'm driving if I look carefully out my side mirrors, and when I'm sittin in traffic or at the traffic lights the smoke tends to rise and blow past my windows, when I pull off I can see a cloud of smoke....can anyone let me know their thought please, could be the valves, rings, seals or head gasket?

[X5Sport]

One of the turbos may be the right call.  You have a high pressure oil feed to the centre bearing.  If a previous owner hasn't allowed the car to warm up/cool down properly when being used at motorway speeds it can 'cook' the oil in that bearing (as it gets very hot) and lead to seals failing.

It could equally be the other items you mention, however those failures are pretty rare on BMW engines whereas turbo failures are more common which may well be why the garage is leaning towards that option.

Head gasket might show mayonnaise under the oil cap (mix of oil/water).

Keep an eye on it for the turbo as a sudden failure of the bearing seal in the exhaust side can cause a runaway.  This is where oil burns in the turbo and it acts like a miniature gas turbine causing the engine to accelerate uncontrollably.  Turning it off has no effect as the oil is the fuel feeding it, not diesel.  It runs until it siezes or you manage to block incoming air (which stalls it).  This only happens when the system is very hot, and the turbo seals fail catastrophically so you will get warning of that as the smoke will get a lot worse.

[lezmtaylor]

Diesel engine runaway is serious news.
I used to be a forklift mechanic and a customer had a diesel runaway caused by overfilling with engine oil(luckily I was on site when it happened), the only way we could stop the engine was to stuff a heavy really large piece of rag into the air filter. I was frightened stiff, they all thought it was a great joke, I never went back there again !!!

Lez