N55 Constant PCV Failure

[bnace10]

Hey all,

I'm familiar with the issues with the N55 and the PCV that is internal to the valve cover (squealing at idle and deceleration when the oil is hot).

I had a shop replace the valve cover ~2 years ago (just due to an oil leak), and immediately had a failed PCV while still in their possession, so they replaced it again. They also replaced the front crank seal.

Within 3 months, that second new valve cover PCV failed, and I have just been driving it that way and ignoring the squealing.

Does anybody know why this could be happening? I thought maybe a piston ring was bad and forcing extra pressure into the crankcase and rupturing the PCV baffle thing, but I don't burn or lose a drop of oil in between changes. Could this all be because of a bad front crank seal? I don't know because again, no oil loss.

It's going there again on Monday for an alignment post M3 LCAs, and they are going to try and diagnose it, but thought I'd see if anybody else here had this issue.

Thanks for all your help!

[N55e82Simon]

Was the replacement OEM? I have had cheap pcv’s fail multiple times on other cars that I replaced with OEM part and was fine after.

[bnace10]

Originally Posted by N55e82Simon

Was the replacement OEM? I have had cheap pcv’s fail multiple times on other cars that I replaced with OEM part and was fine after.

Yep, all OEM parts.

I'm thinking maybe a vacuum leak, but wouldn't that cause lower crank case pressure?

[bnace10]

Now onto the 3rd valve cover and it’s still squealing.

They were honest with me and said they have no idea, and last ditch effort is to replace the vacuum pump to the tune of $1,000.

Hopefully this fixes it, but the shop didn’t seem all too confident, but said it’s the only thing they could possible believe causing excess crankcase pressure.

Fingers crossed…

[tracer bullet]

Sucks to hear. At this point you might want to consider a BMW dealer. Might have been best before the most recent replacement. Hopefully it was still under warranty. If not it might be another reason to check a dealer, I'm not sure their policies but you'd hope that OE parts and dealership labor would equal at least a year or more. They'd possibly have more knowledge of what's going on.

[bnace10]

Originally Posted by tracer bullet

Sucks to hear. At this point you might want to consider a BMW dealer. Might have been best before the most recent replacement. Hopefully it was still under warranty. If not it might be another reason to check a dealer, I'm not sure their policies but you'd hope that OE parts and dealership labor would equal at least a year or more. They'd possibly have more knowledge of what's going on.

The 3rd valve cover I believe was just them testing, I imagine they didn't replace the 2nd one as they didn't charge me for it.

The first 2 replacements happened back to back while it was in their possession, and that was covered by CarMax warranty shortly after I bought it. So, so far nothing has come out of my pocket until this new Vacuum Pump, which I guess is a positive side.

[bnace10]

Well, I'm happier than a pig in shit!

The garage, Kassel Performance, told me it was a Hail Mary fix of replacing the vacuum pump, but god damn, it's fixed.

Granted it's only been 10 hours and 30 miles since I picked it up on my lunch break, but so far so good. No more squealing RMS or front crank seal. No more slight jumping at idle from the vacuum leak of air going past the seals.

They said they believed the vacuum pump was malfunctioning and pulling too much vacuum causing air to be sucked in through the seals causing the squealing/whistling rather than it being caused from a bad PCV pushing air out.

They also said this is the first case of an N55/S55 they've ever seen have an issue with the vacuum pump. I opted to let them fix it as they had already done all the diagnostic, and since this is a super rare issue there are 0 DIYs and the specialized tools are >$300.


Hopefully this saves anybody with this issue the hassle, though I doubt many will ever have this issue if I was the first one this top notch garage had ever seen.

[N55e82Simon]

Fingers crossed it stays fixed this time. Glad it is working now though. That’s a great feeling.

[corbinwhit]

Originally Posted by bnace10

Well, I'm happier than a pig in shit!

The garage, Kassel Performance, told me it was a Hail Mary fix of replacing the vacuum pump, but god damn, it's fixed.

Granted it's only been 10 hours and 30 miles since I picked it up on my lunch break, but so far so good. No more squealing RMS or front crank seal. No more slight jumping at idle from the vacuum leak of air going past the seals.

They said they believed the vacuum pump was malfunctioning and pulling too much vacuum causing air to be sucked in through the seals causing the squealing/whistling rather than it being caused from a bad PCV pushing air out.

They also said this is the first case of an N55/S55 they've ever seen have an issue with the vacuum pump. I opted to let them fix it as they had already done all the diagnostic, and since this is a super rare issue there are 0 DIYs and the specialized tools are >$300.


Hopefully this saves anybody with this issue the hassle, though I doubt many will ever have this issue if I was the first one this top notch garage had ever seen.

Thank you so much for documenting this issue. I’ve been experiencing the same exact problem with my 2011 e90 335i for over a year now. Went through two valve covers and was just about to replace the front crank seal as well. Looks like I’ll be replacing this next.

[bnace10]

Originally Posted by corbinwhit

Thank you so much for documenting this issue. I’ve been experiencing the same exact problem with my 2011 e90 335i for over a year now. Went through two valve covers and was just about to replace the front crank seal as well. Looks like I’ll be replacing this next.

From what I can see on N55 tear down/rebuild videos, you'll need the vacuum pump and a Vacuum Pump Seal:

Vacuum Pump: 11667619350
Seal: 11117530262

It seems like you destroy the seal to get it off, and it requires special tools (~$300) to put the new one in. Those tools also come with tools to hold the sprocket in order to get the vacuum pump out (it's run off the timing chain).

You also have to pull the HPFP because the HPFP runs off back of the vacuum pump. You have to remove belt and tensioner and what ever else is required for the HPFP (intake manifold, etc.)

This might be a job I'd just pay somebody to do because after the parts, tools, and time you don't save all that much money. I was charged $307 for the Pump, $30 for the Seal, and 5.7 hours labor (@ $135/hr).

Edit: SS the part of the invoice relating to the vacuum pump below

[bnace10]

Originally Posted by corbinwhit

Thank you so much for documenting this issue. I’ve been experiencing the same exact problem with my 2011 e90 335i for over a year now. Went through two valve covers and was just about to replace the front crank seal as well. Looks like I’ll be replacing this next.

Several week later update:

Still chirping a bit, but much less than before, however it no longer "kicks" at idle, so somehow it fixed a minor vacuum leak.

I have no damn clue honestly, but I'm done trying to "fix" this issue for now.

[corbinwhit]

Originally Posted by bnace10

Several week later update:

Still chirping a bit, but much less than before, however it no longer "kicks" at idle, so somehow it fixed a minor vacuum leak.

I have no damn clue honestly, but I'm done trying to "fix" this issue for now.

Jesus Christ. This problem will drive me insane if i let it. I have no idea what else could be causing this

[FrostyDC4]

Originally Posted by bnace10

Several week later update:

Still chirping a bit, but much less than before, however it no longer "kicks" at idle, so somehow it fixed a minor vacuum leak.

I have no damn clue honestly, but I'm done trying to "fix" this issue for now.

This started happening to my car recently and AFAIK the valve cover has not been changed so I will be changing this soon. The problem gets worse when I am boosting at very low rpm (below 2k) or putting around town at low rpm (below 2k). The issue should go away if you lay off the boost below 2k and/or keep your cruising rpm's above 2k.

[bnace10]

Originally Posted by FrostyDC4

This started happening to my car recently and AFAIK the valve cover has not been changed so I will be changing this soon. The problem gets worse when I am boosting at very low rpm (below 2k) or putting around town at low rpm (below 2k). The issue should go away if you lay off the boost below 2k and/or keep your cruising rpm's above 2k.

It doesn't chirp when on throttle, only when decelerating at low speed, and at idle. Your issue just sounds like a vacuum leak somewhere.

[FrostyDC4]

Originally Posted by bnace10

It doesn't chirp when on throttle, only when decelerating at low speed, and at idle. Your issue just sounds like a vacuum leak somewhere.

My car made the chirping/whistling sounds only at idle until I changed my driving style. I did the oil cap test and I am pretty sure its the valve cover. I wouldn't brush off symptoms like this since they can lead to very messy & expensive fixes (if you let it go long enough you will end up spending 4-5k to replace the front & rear main seals of the motor). The PCV systems of the N54, N55, and B58 cars are pretty bad and all of these motors succumb to these issues.

The DCT cars when left to their own vices will cruise and boost in the highest gear possible (I would never do this driving a MT turbo car).

[TWO STEP TEX]

Originally Posted by bnace10

It doesn't chirp when on throttle, only when decelerating at low speed, and at idle. Your issue just sounds like a vacuum leak somewhere.

Question, what kind of accessory belt are you using? I had some chirping, thought it was the valve cover, it wasn't. Changed my belt and tensioner and the chirping went away for a few days but then returned. Replaced tensioner again, same thing. Finally ordered the BMW OE belt to replace the Continental and problem solved. The OE belt seems to have an almost felt like coating vs the Continental. Been 2 months now with no issues, was definitely the belt for me.

[bnace10]

Originally Posted by FrostyDC4

My car made the chirping/whistling sounds only at idle until I changed my driving style. I did the oil cap test and I am pretty sure its the valve cover. I wouldn't brush off symptoms like this since they can lead to very messy & expensive fixes (if you let it go long enough you will end up spending 4-5k to replace the front & rear main seals of the motor). The PCV systems of the N54, N55, and B58 cars are pretty bad and all of these motors succumb to these issues.

The DCT cars when left to their own vices will cruise and boost in the highest gear possible (I would never do this driving a MT turbo car).

I've been through multiple brand new valve covers...

It isn't from coming down from boost. I notice it most often when crawling in drive thru's with just enough throttle to move faster than the idle crawl.

[greezy_goblin]

Originally Posted by bnace10

I've been through multiple brand new valve covers...

It isn't from coming down from boost. I notice it most often when crawling in drive thru's with just enough throttle to move faster than the idle crawl.

I had an issue where, admittedly I forgot to plug in the PCV Hose on the back of my N52 valve cover, and it made a sound almost like metal rubbing on metal, so you could try double checking the PCV hose going from the left of the valve cover to the intake. While doing Valve Cover Gasket replacement on 2 separate N55s I had these crack on me, with the vehicle at less than 60k. Double check fitment/addition of heater, but here is the link so you can at least see what I’m talking about https://www.fcpeuro.com/products/bmw...se-11127590163 (it is on the front of the N55, compared to the back on N52 and N54)

[FrostyDC4]

Originally Posted by bnace10

I've been through multiple brand new valve covers...

It isn't from coming down from boost. I notice it most often when crawling in drive thru's with just enough throttle to move faster than the idle crawl.

Have you checked the coolant overflow to make sure its not running low? Do the oil temps come down when letting the car idle after boosting hard?

If you let this go long enough it can cause issues with the vanos/valvetronic system.