oil separator noise: normal?

[Breeze1]

Hello all,

First of all I'd like to mention that I'm aware I have been posting a lot of questions regarding a lot of things lately, and I appreciate A LOT all the help you guys provided me with. It's just that fixing/maintining a car here is more difficult than (I suppose) in the US, since most mechanics have learned their trade through practicing and hearsay. So sometimes they think they're doing something right while they'are actually doing it completely wrong. I end up having to double check things on the web and have them do the right thing afterwards. I live in an apartment buiding so it's difficult/impossible for me to do most tasks by myself, otherwise I would be the only one working on my car, no matter how long it takes or how difficult it might be.

To the story then: last week when I took off my Intake manifold to look for leaks, my mechanic told me that my oil separator was bad, because when he blew through one whole he felt that the air was flowing completely free, without any resistance, which is a sign that the membrane inside it was no longer there and therefore the oil separator was not doing its job. He claimed that the one he had, because it had this "resistance" to it, was good, so I said "ok let's change it" since I have been doing literally everything I can to get rid of the misfires I have been experiencing (exhaust manifold leak and fuel pump are scheduled for tomorrow) and I thought that it would be the opportunity to change it "while we were there".

After putting back the IM (and putting a missing cap in it as well as in the hose coming from below the car, thanks Chris), the misfires are still there altough reduced and more focused on low rpms than high ones (yeah I know, it sounds counter intuitive since the intake leaks have been fixed), but I no longer have the rpm needle dipping issue when coming to a stop. It settles right away at its idle speed and stay there very steadily.

What I do have on the other hand, is a noise that is much less loud than the one described in the video below (about 20% of it), not when the car is actually running, but immediately after turning it off. It only last 1-2 secs. The mechanic claims that it is normal and that the car should make that noise, I think it isn't...

So before asking him to remove that one and put mine back in (what a PITA), I thought I would double check with the pros here.

https://youtu.be/Nbp5GkGAwLw

[bmwdirtracer]

Honking is bad. It indicates a torn diaphragm. It shouldn't honk when you shut off the engine, and shouldn't honk with the engine running, an shouldn't honk with the oil cap off, either. As for whether you can freely blow through a CCV separator, I don't know. I do a crankcase vacuum test, looking to see 3-6 inches of water, vacuum....and replace the four pipes and the separator if not.

You know you can make your own manometer really easily, for this test? See O2Pilot's epic CCV thread, page 8.

[Breeze1]

Thanks Chris! I think I'll have to put mine back for now. It was not honking... there were traces of oil (basically a thin layer/greasy surface) in the IM though, where the DISA valve sits and I don't know if that is normal either. I'm thinking it is since oil fumes are supposed to be redirected into the IM by the ccv system, but I could be wrong.

The pipes were all thoroughly checked and seemed fine.

Only problem is it means taking the IM off again, which is time consuming, and we were planning on solving the exhaust manifold leak, which is even more time consuming lol (the bolts have already been tightened so the persisting leak means there must be somethig wrong with the gaskets. We'll have to take the whole thing apart to replace them).

I'll make sure to take a look at O2Pilot's thread!

[bmwdirtracer]

A coating of oil in the manifold is normal.

You don't have to remove the manifold to change the oil separator.

[bmwdirtracer]

If it's not honking, what sort of noise is it making? If you pull off the oil fil cap with the engine running, how weak or strong is the vacuum? It should be very weak, but present.

[Breeze1]

The other one (the one we replaced) was not honking and the vacuum was exactly as you describe, which seems to confirmed that it was good. The one currently in didn't honk with engine running and cap off, but it does a little bit when you turn it off. It's exactly the same noise as in the vid, but at a much lower volume. I hope we're good enough to figure out how to remove it without removing the manifold, because the way I remember it, it's "way down there".

Edit: working on removing it without removing the manifold, from the right side, where the DISA sits

[bmwdirtracer]

Remove both intake elbows , unbolt the plastic wiring bundle from the side of the manifold and disconnect whatever plugs you need to (ICV, DISA, etc.) to get it out of the way.

Remove the throttle body, remove the oil filter cap and filter, to give yourself more room to get the plastic pipes disconnected from the separator. Be very careful with the oil return tube, because it likes to rip in half, or crush, inside the webbing where you can't see it.

After that, there are just 2 screws (T20 or T25) holding the separator to the manifold. One is a bit concealed, a mirror helps to see it, but it's accessible.

[Breeze1]

Thanks Chris. We were able to remove it and put mine back in without taking the IM off. It's confirmed that mine is missing the membrane (you can't see it "peaking" from a little opening like in the one my mechanic has) but at least it doesn't honk and it's free lol.

We've also tried a few things to solve the misfiring issue, to no avail. I'll follow up on that on my other post so the forum keeps making sense...

[bmwdirtracer]

If your CCV (separator) doesn't have a diaphragm, you have a massive internal intake system leak. You'll be pulling full intake vacuum on the crankcase -- that's up to ~20 inches of MERCURY, which is, oh, 43 times the vacuum you should have.

Try removing the oil fill cap with the engine running now, let's see if all this is really true.