4.8i Vacuum Leak - Help Needed

[juthale]

Well, it's been a rough month for the X5. First it was the expansion tank, and now on Tuesday she blew a cloud of bluish white smoke that obscured the sun for most of Seattle. It was truly spectacular.

The smoke screen occurred after sitting at idle for 10-15 minutes. It took 30-40 seconds to completely clear out of the exhaust system, but then there was no more smoke. The X5 ran normal, except for a CEL and codes 2187 and 2189 reading on the OBD2 (System Too Lean at Idle - bank 1 and bank 2, respectively).

It appears I am in good company. More than a few BMW owners have watched in horror as their pampered engine produces such a cloud. As such, there are plenty of threads on the topic. After reading as much as I could find, it seems there are two knee-jerk diagnosis for this problem. Many immediately point at the valve stem seals, while others say an air leak into the engine is permitting oil to free-flow with through the crankcase vent system into the intake manifold. Hopeful it was the latter, I pulled the induction system off the engine then pulled the crankcase vent lines. Here is what I found:

From the left cylinder bank, the vent line was wet with oil. On the right bank, not really wet, but very caked up with sludge. Where the lines entered into the intake manifold, it was both caked and wet.


Vent line from right bank:


Vent line from left bank:


Looking into the intake manifold through the throttle body, it is quite wet and oily looking:


I'm certainly relieved to see oil entering the intake, as an air leak causing oil to enter the crankcase vent is a much simpler fix than valve stem seals.

Here are my questions:

On the N62 engine, are there diaphragms in the CCV system, as there are on the M62 & N63?

Could it be as simple as just a broken diaphragm?

Is there a good way to troubleshoot and isolate the air leak? (I don't mind taking on a challenging diagnosis procedure, but would need a some idea how to go about it).

I have heard of people changing every seal and gasket in the top end of the engine to solve this problem (valve covers, intake manifold, injectors, VANOS, fill cap, dipstick, etc. etc.) This seems like overkill when it is likely there is only one problem needing to be fixed.

Any help would be appreciated... there's only one month of the driving season left here in Washington!!!

[juthale]

So I found the answer to my questions...

The N62 has 2 diaphragms in the crankcase vent system - one in-line on the vent tube for the right bank and one mounted in the valve cover for the left bank. Looking at BMW's online parts catalog, it seems some N62s have both diaphragm valves located one in each valve cover, but on mine this was only the case on the left side.

The diaphragms were oily and dirty with some chunks of sludge, but no cheese. On the right side, everything looked OK. On the left side (the wet side) the diaphragm was brittle and cracked - a 1" tear in the diaphragm was the obvious source of my unregulated crankcase vacuum and why I was pulling oil into my intake.

Two Bosch replacement diaphragms from NAPA cost me around $60. I'll put them in over the weekend and let you know if it solves the problems.

Glad it was not valve stem seals! Also, REALLY thankful for the helpful member who provided THIS BMW TECHNICAL SERVICE BULLETIN:

http://tsb.deccats.com/tsb-bmw_all-evap.pdf

[A B Able Truck]

Originally Posted by juthale

Looking at BMW's online parts catalog, it seems some N62s have both diaphragm valves located one in each valve cover, but on mine this was only the case on the left side.

This is why;
http://www.xoutpost.com/attachments/...b-11-01-07.pdf

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[juthale]

Excellent. Thanks A B Able Truck! Your BMW service bulletins are saving the day for me on this one! It's reassuring to see evidence the first owner of this vehicle took care of the recall items.