[Vaurifort]

I have a 2012 E93 328i, N52 w/ 99k miles. Last year I manual swapped it and it was like almost immediately after doing the swap, my oil consumption went from needing to put a quart in like every 3-4 months(2400-3200 miles to needing to put a quart in every month(roughly 800 miles). I have already changed my OFHG, and Oil pan gasket. I cant really find a leak or at least I cant find any evidence of that bad of a leak on the engine. It doesn't smoke, nor am I getting any codes for misfires or anything. Yesterday, I got a vacuum gauge/pump to test the diaphragm in the valve cover, by removing the little cover over the nipple to it and hooking up the pump/gauge and trying to see if it would hold a vacuum, It wouldn't hold anything, it was leaking as fast as I could pump it. After that I tried seeing if I got a vacuum leak from it when the engine was on, and it would pull air, had to test by holding a thin glove next to it but it was absolutely sucking in air. Another thing I noticed was that when I covered the hole where the oil cap goes with my hand, I could get it to squeal/squeak as if it was pulling in air from around the crankshaft. I'm leaning towards replacing my ccv hoses and valve cover but I don't want to spend all that unless I know that is going to fix my oil consumption problem. Might anyone have any ideas? Sorry, if that was long winded and/or poorly worded but I've been at wits end since I started trying to figure it out about a week ago. I appreciate any and all help!

[e90yyc]

This exact same thing happened to me, down to practically every detail.

1. Similar oil consumption to you while my car was auto
2. Manual-swapped it and immediately noticed significantly increased oil consumption
3. Was certain something had to be leaking but could not see oil anywhere (and I looked realllll hard)

Following this discovery:

• Was certain I fucked up the rear main and went through a short-lived period of minor depression
• Confirmed it is NOT visibly leaking, at least as far as I can see through the plug at bellhousing
• Checked compression; all cylinders ~190 psi
• Tested PCV diaphragm; seemed okay
• Ended up replacing probably-good parts chasing the issue (including valve cover)
• Issue persisted
• Set up camera to observe exhaust, and then mashed the throttle
• Saw puff of blue smoke in video
  
• Concluded that valve stem seals are the likely cause, and the sudden drastic change is the result of significantly higher average RPM with the manual, made worse by the fact I still have the 3.91 diffs

Bottom line
All else equal, I think you can safely conclude that you don’t have some massive undiscovered leak. My guess is that, as is the case with me, the driver of your oil consumption is the higher average revs with the manual. I don’t even hoon, but the unavoidable fact is that the auto shifts at such low engine speeds (especially 1-2) and trying to mimic that with the manual is something I’m not good at.


PCV Testing
Regarding your test of the PCV diaphragm: When you connected your vacuum pump to the nipple, were you pulling vacuum or pumping air and creating positive pressure? As I understand it, testing is best done with a small hose and no tools other than your mouth. You should be able to blow a small amount of air IN before it stops you; and trying to pull vacuum with your mouth should result in membrane sealing and preventing you from drawing any meaningful amount of air out. (Careful testing the diaphragm on the VCG with a vacuum pump; as I understand it, you can damage an otherwise-good membrane by subjecting it to excessive pressure. This could be bullshit but considering how fragile this thing seems to be, I heeded this advice.)

[Vaurifort]

I'm so glad you replied. I actually had read a few of your posts about you having the same issue a while back before I just kind of stressed myself out over it and stopped caring for a bit.

When you recorded the engine starting, was it from a cold start, and after letting it warm up from there, you mashed the throttle on camera?

As for PCV testing, while the car was off, I got one of those hand pump vacuum testers that also work as a brake bleeder and hooked that up to the nipple and pumped a couple times. It would not build up any pressure at all. I tried sucking on it with a hose and my mouth and I was able to suck air through it(however I did not try to blow through it, I can go back and try that), it never really felt like it was going to stop or slow down on how hard I could suck.

[e90yyc]

Originally Posted by Vaurifort

I'm so glad you replied. I actually had read a few of your posts about you having the same issue a while back before I just kind of stressed myself out over it and stopped caring for a bit.

When you recorded the engine starting, was it from a cold start, and after letting it warm up from there, you mashed the throttle on camera?

As for PCV testing, while the car was off, I got one of those hand pump vacuum testers that also work as a brake bleeder and hooked that up to the nipple and pumped a couple times. It would not build up any pressure at all. I tried sucking on it with a hose and my mouth and I was able to suck air through it(however I did not try to blow through it, I can go back and try that), it never really felt like it was going to stop or slow down on how hard I could suck.

No problem!

Sorry—I meant to say I did this check with the engine COLD. Regardless, I’m sure it would still be pretty apparent even with engine warmed up.

Try checking the PCV membrane using a hose and gently blowing a small amount of air through. See PhaseP’s excellent post here on the PCV system and how to test it.

[e91Owner]

It sure sounds like a bad PCV to me. The best solution is a new VC, but you can also buy one of the PCV kits to just replace the diaphragm. Not super easy since you have to cut off the old one, but also much easier than replacing the whole VC which is a bitch to wiggle out.

[Vaurifort]

OK update:
I recorded a few cold stasrt and a few really high revs after it warmed up(1o minutes) and there is zero smoke at a cold start up. After warm up and a high rev there is what appeared to be a tiny puff of smoke but it was so small I could not tell what colour it was.

I also took my engine cover off again to test the ccv again and this time I blew on it. I just kept blowing into it, it never stopped me or even slowed down. I also sucked and same, I could just keep sucking; note, it tasted like oil, go figure lol.

So I think I'm leaning toward a VC. I'm also considering the diaphragm, that you have to carefully cut out, as e91owner was mentioning.

[e90yyc]

Probably not a bad idea to replace it in that case. For me, it didn’t appear to be the case as mine checked out, but like many things I’ve replace on my car, I still went ahead and replaced it anyway, haha…

I should note that the amount of smoke I saw when revving my engine was not significant, but it was still something.

Not that it’s your best option, but I do still have my old VC on hand and would sell it for cheap. I know it’s used and not worth much, but I’d be happy to confirm the PCV valve is behaving correctly if that’s something you’d be interested in.

My honest opinion on VC replacement is that it’s not as bad as it’s made out to be. As long as you remove the fastener(s?) holding the cowl trim piece, getting the VC in isn’t too bad. If you don’t do this, then yes, it will be an infuriating time, haha…