Smoking problem: Fixed

[stiubhartach]

Smoking problem fixed.

My X5: 2005 X5 4.4 130k miles. One previous owner, garaged, always maintained at dealer with complete records. Very clean with most common problems already fixed by the dealer.

Problem: A couple of weeks after I purchased my BMW, I noticed a cloud of smoke at take off after idling. So, I do research and read repair records.

1) records show that the CCV system was repaired in the months previously by replacing torn diaphragms.

2) It appears that it did not fix the smoking problem, so the dealer told the PO that it was most likely valve stem seals and would be thousands to fix. So he sold it cheap.

3) I got a good deal on a clean car, but didn't know about the smoking until after purchase.

4) CCV research is very confusing due to model changes.

5) I'm experienced in the auto world, but this is my first BMW and the systems are different in some ways.

6) For the novice: BMW CCV systems are what on an American car would be refered to as the PCV system. Crank case ventilation system vs positive crankcase ventilation system. Both pull blow by gasses out of the crankcase and burn them.

7) BMW CCV is different in that there is less vacuum in the intake manifold due to the Vanos System. There is not a constant flow of suction from the top of the engine. There are two rubber diaphragms that open and close by vacuum to keep oil from entering the tube and getting sucked into the intake manifold.

8) There is no smoking on start up. Only when it sits at idle for a while. I don't believe it is the valve seals. Valve seal problems manifest mainly by oil leaking slowly down the valve stem while the engine is off and pooling in the cylinder. At startup, the oil is burned in a big cloud.

9) I am puzzled, so I do some exploration. Pull the throttle body and look into the intake manifold with a fiber optic scope. See visible oil inside the manifold. So that is how the oil is getting into the combustion chamber. How is the oil getting into the manifold?

10) Do more research. Find oil in the hose to the intake from the CCV valve.

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 vacuum.

13) The moron dealer technician did not clean out the CCV body when changing the diaphragm.

14) This was good for me, as I got a good car for a great price. Bad for the PO as he didn't really need to do thousands of dollars worth of repairs.

15) Cost to me: a few hours and $30 for new diaphragms.

Result: over a year now of ownership and not a hint of smoke or oil burning. Oil consumption is about a quart every 4 months. ( small seep at a front gasket)


I also want to thank you all for the excellent information on this site. It's helped out many times. I hope to give back when I can.