Smoking problem: Fixed
 

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.

Thanks for sharing!

Grrrreat Post and well thought out approach to a problem that is heavily documented but still trips up lots of owners and some now well documented techs.

Good job and congrats on the purchase!:thumbup:

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?:dunno: 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 :rolleyes:

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!......:D

Thanks for sharing!

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.

I did mine the year I bought my 4.8is, also there are MANY things to make Her to be at the best to 100% .
Do You want to know, just ask.

If the engine smokes at start up, it is usually valve stem seals or a dripping carb or injector depending on the color of the smoke. Or coolant which is another issue all together! It takes a lot of oil burning to make a visible cloud. The amount of oil seeping past valve stem seals while the engine is running will not usually be visible to the eye. A slow seep while off can lead to enough over a few hours to make the cloud on start up. So, if there is no start up smoke, then I would bet that it is not the valve stem seals. I'll try to clarify where my problem was. I failed to take photos, so I'll try and locate enough to work. I take no credit for any photos in this post.

1) To clarify some points first. The Vanos system creates a low pressure vacuum situation in the intake manifold. That makes venting the crankcase a little more difficult than other engines.

2) BMW changed from an external oil separator and diaphragm system to an one that is integrated into the valve cover. This seems to have been done to stop the freezing of the system in cold weather which led to oil being sucked into the cylinders and hydro locking and destroying the engine. I'm not sure, but I think I recall the change was from the m62 to th n62 engines. Someone else can correct me if I'm wrong.

3) here's a quote from a manual where it calls the diaphragm assembly the " pressure control valve and says that it controls the crankcase pressure.

" The remaining vapors are passed to the engine for combustion via the pressure control valve (5) in the intake manifold. One labyrinth separator with a pressure control valve is inte-grated in each of the two cylinder head covers.

The throttle valve is controlled so that there is always a 50 mbar vacuum in the intake man-ifold. The pressure control valve regulates the crankcase pressure to a low 0-30 mbar. "


The manual link and is on page 12:

http://www.internetsomething.com/lpg...2%20Engine.pdf

I'll continue in next post.

4) this is the diaphragm that needs changed periodically. It controls the vacuum in the crankcase and fits into the top of the valve cover. The central orange ring is one of the sealing surfaces as well as the outer area. The plastic cap seems to break tabs when it is pulled off.

http://c1552172.r72.cf0.rackcdn.com/560973_x800.jpg

5) this is a view of the valve cover with the integral pressure valve/ CCV valve.

https://c1552172.ssl.cf0.rackcdn.com/207331_x800.jpg

6) here's another view of the CCV valve from Pelican parts.

http://www.pelicanparts.com/techarti...mall/pic10.jpg

7) this is a view of the inside of the valve where the gunk was. Photo is from a thread on this site. Photo is a little blurry, but other good photos on the other thread. This is the link to the thread.

http://www.xoutpost.com/bmw-sav-foru...nt-repair.html

http://www.xoutpost.com/attachments/...air-bmw007.jpg

8) this is similar to what the integral valve looks like inside. This is NOT the one on the n62. I think this is the external one mounted on the back of the m62. I might be wrong though. The passage toward the bottom is the oil drain to allow the oil to flow back into the engine. If it is plugged and the oil pools then it will get sucked not the intake manifold. Also, under high vacuum like acceleration, the central port is closed by the diaphragm. It only allows flow from the crankcase into the intake under light vacuum. I think this is what was not sealing in my problem. Under acceleration the high vacuum would suck pooled oil out of the valve and directly into the left side of the manifold and into the cylinders.

http://i895.photobucket.com/albums/a...ps420ef221.jpg