just inspected/passed, now throwing codes at me

[workingonit]

I finally got somewhere in my search for the vacuum leak, that must be causing my codes. First, I looked for loose or spongy rubber hoses coming off the SAP, and the F-connector attached to the intake elbow . They were fine, and felt & looked certainly less than 21 years old (fresher than some on my '09 HHR). Then I got out my cheap borescope to look behind and below the engine.

That's when I spotted a hose, unconnected next to the steering shaft (turned out to be a plastic tube), that was curved upwards towards an unknown spot. For the life of me, literally, I jacked up the left front of the X5, put a 3-ton jackstand under the steel subframe, and crawled under from the left side, Got this photo, but couldn't see where it is supposed to connect (the other end rises up towards a vacuum source above, I guess).
spotted it from above
it rises past the dipstick
from below, it is plastic

Can anyone identify where this open-end connects? I saw nothing while under there, and there sure isn't room to explore. My jack & jackstand are both resting on 1/2" plywood, and cutting thu it as I write this; I'll have to put the X5 back on the ground for safety.

And how does anyone actually reach behind the M54 anyway? do I have to take off the windshield washer tank? The only other way in that I see would be to remove the air dam? where the cabin filter housing is. Looks like the brake hose & other lines run through it.

[oldskewel]

That constant radius curved end is a clue. Is it hard plastic? Does the open end appear that it has never been attached to anything (e.g., no deformation from a clamp or barb or change in diameter)?

It could be a vent for the differential. One end attaches to the diff. The tube then goes upward, ending in that 180* u-turn so the open end is facing downward so nothing falls in.

[oldskewel]

That constant radius curved end is a clue. Is it hard plastic? Does the open end appear that it has never been attached to anything (e.g., no deformation from a clamp or barb or change in diameter)?

It could be a vent for the differential. One end attaches to the diff. The tube then goes upward, ending in that 180* u-turn so the open end is facing downward so nothing falls in.

[workingonit]

I doesn't appear deformed at all, but it is clearly rising up behind the engine. I can't turn the upward curved end where it might face downward.

I also spotted the rear of the manifold, where there are two new, fresh-appearing caps, and there's another spot (a hard plastic "boss"), where it looks like there should be a fitting. I can't see anything very well, and the Realoem drawings are crude. Still looking.

Could it be part of the fuel tank breather line 13907557924, that looks to be made of hard plastic, with rubber ends? Now, to find where it connects up.

[oldskewel]

The differential vent I'm talking about attaches to and parallels the dipstick tube in my 2001 3.0i.

The main distinction of this vs. the other hard plastic tubing you'll find is that it terminates in a constant radius 180* u-turn. That sort of an end is not so common other than for applications like this.

I expect searching on this site for that will give some photos.

[workingonit]

On Realoem, the only line I find with an upturn is a fuel feed line from the filter/regulator to the engine bay.


Is that a vacuum line? The other line shown is a pressure line, so the engine should be able to run without the "feed line".

I'm having trouble with BMW terminology, technology, and unusual placement of components. I dealt 99% with American cars, 1% foreign cars, and most of them were General Motors cars over the last 5.5 decades. I figured that my first BMW would be a challenge, but looks like I'll have to re-learn everything as I go. oldskewel, at least you've got an eight-year head-start on me, so lead on!

[wpoll]

+1 on it being the front diff vent...



https://www.realoem.com/bmw/enUS/sho...diagId=31_0547

[workingonit]

Originally Posted by wpoll

+1 on it being the front diff vent....

Sure looks the part, and I finally located the other end going behind the engine into the transmission tunnel (but didn't see what it connected to).

It's a vent tube alright, but how the heck did it get turned upside down and backwards? without breaking! and where is the "bracket" it attaches to? There seems to be a choice of two, according to Realoem.


I'll find something to attach it to, after I make the opening face down. I'm sure to find more misbegotten malassembled items in my search for the vacuum leak (this isn't it).

And, regarding how to get behind the engine to look for vacuum pieces:

Originally Posted by workingonit

And how does anyone actually reach behind the M54 anyway? do I have to take off the windshield washer tank? The only other way in that I see would be to remove the air dam? where the cabin filter housing is. Looks like the brake hose & other lines run through it.

I think I've found it; there are two bolts holding an undertray below the microfilter area. There are angled guides to help slide it back into place (I think). Added 3/25 here's a couple of videos showing how to do it: https://youtu.be/Qxo5tg1qVRc or https://youtu.be/Eq00ZAOwc88 works on both 3.0i and 4.4 engines. I'll try it Monday, after the wife gets home (I limit my undercar activity, and also disabling vehicles, to times when I can get an unwilling assistant, to lend me a hand).

[oldskewel]

One end of that tube goes into the top of the front differential.

The other end attaches (around those two radial rib things a few inches before the u-turn) to a bracket near the top of the engine oil dipstick tube. I expect if you forget about the vent tube for a moment and look at your dipstick tube you will see some clues that make it clear.

I have the same car as you - 2001 3.0i, same color too, and that's how mine is.

[workingonit]

I gave up trying to squeeze in under the X5, sitting precariously on one jackstand, resting on a broken board on sand/gravel. I dug out my "truck" ramps that had been under my trailer in the garage, and drove the X5 up onto them. Much better, feel safer underneath.

While under there, I looked around at all the "new to me parts", and was pleased to see no sign of leaks (some seepage, though, on the oil pan), no loose or missing parts, and driveshafts, guibos, and rubber boots were good. My friend that was fixing it up for me over the previous 3.5 years before we swapped cars, did a good job. I haven't found the source of my codes, but they started months after I got the X5 from him.

I did re-route the mystery tube to near the bracket that had an empty clip; that must be where it had been, so I just zip-tied it to the dipstick, instead, because my fingers weren't nimble enough to use that clip. Fair enough.
here's the empty tube clip

I put the truck back on the ground, and tomorrow I'll start afresh, looking for the source of the vacuum leak. I found out how to remove the micro filter housing, etc. from over the engine (I added an addendum to my previous post about two videos that clued me in). Smoke tester first, carb cleaner second (while the engine is idling, while monitoring the Torque Pro app on my phone), and hope for the best.
Added 3/26: homemade smoke tester failed after warm-up, the $7 soldering iron burnt-out after only 30 minutes of total usage...my advice, don't build one like mine!