Smoking problem: Fixed

[X5only]

Originally Posted by stiubhartach

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11) Pull the CCV valve apart. Find a new diaphragm, but lots of old burnt oil and dirt caked around the sealing surfaces. See oil pooling in the valve where it should not be. Drain passage back into the engine is clogged.

12) Verdict: the CCV diaphragm was unable to seal correctly due to filth. The oil was unable to return to the engine also due to filth. Therefore the oil was getting sucked into the intake after a period of running with low ..
helped out many times. I hope to give back when I can.

This is an incredible post, Stiubhartach! My '05 4.4 smokes only after idling but never upon startup, even after weeks upon weeks of being parked. Or does it only leak under vacuum? I also noticed that it's from the left exhaust only. I'm just a weekend DIY and accepted without question that my issue is of course valve stem seals, and never did any systematic investigations to verify this supposition. The smoking onset was quite sudden at around 110k miles and I've been duly performing oil changes with bmw performance oil every 6k miles since I bought the car CPO at around 45k miles. I've been quietly puzzled by this smoking issue but just accepted the common verdict that smoking after extended idling is, of course, the valve stem seals leaking, duh

I've been putting off fixing it and my workaround so far has been to use shell Rotella t6 + 2 quarts lucas engine stop leak + a bottle of atp205 seal conditioner. That formula has been keeping the smoke away for a bit, but on really extended idling it still does smoke. I'm curious what you cleaned and where the filth was in your finding #10, #11, #12. Could you please point out in the diagram below if that helps? I had already replaced the two pcv sometime back (part no. 13), one had a torn diaphragm, but smoking persisted.

I'm just hoping I made the same diagnostic error as that technician at the dealership you bought your X5!......

Thanks for sharing!

[4.8iS Le Mans_NZ]

Great explanation, thanks - and a relatively simple solution to your issue!

My N62B48 engine has a similar smoking issue and likewise, this occurs not at startup but only after periods of extended idling, such as in traffic, etc.

The CCV parts listing for the 4.8 engine (see attached pdf) shows the valve (#4) and tube assy (#1) on back of cylinder head are either deleted from, or not applicable to this engine model, leaving just two pipes there (Item Nos. 2 & 3).
So I'm a little unsure of which CCV system part(s) I should be removing, replacing and/or cleaning on this engine.

Any advice would be appreciated.