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05-16-2023, 07:54 PM | #1 |
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N55 Constant PCV Failure
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! |
05-16-2023, 11:31 PM | #2 |
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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.
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05-17-2023, 09:57 AM | #3 |
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05-23-2023, 11:44 AM | #4 |
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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… |
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05-23-2023, 12:06 PM | #5 |
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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.
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05-23-2023, 05:15 PM | #6 | |
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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. |
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06-01-2023, 08:57 PM | #7 |
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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. Last edited by bnace10; 06-01-2023 at 09:05 PM.. |
06-01-2023, 10:14 PM | #8 |
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Fingers crossed it stays fixed this time. Glad it is working now though. That’s a great feeling.
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06-11-2023, 12:51 PM | #9 | |
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06-11-2023, 08:53 PM | #10 | |
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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 |
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06-19-2023, 02:49 PM | #11 | |
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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. |
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06-28-2023, 08:24 PM | #12 |
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Jesus Christ. This problem will drive me insane if i let it. I have no idea what else could be causing this
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07-12-2023, 12:51 AM | #13 | |
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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.
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07-17-2023, 09:05 PM | #14 | |
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07-20-2023, 01:22 AM | #15 | |
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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).
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07-23-2023, 01:40 PM | #16 |
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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.
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07-23-2023, 02:11 PM | #17 | |
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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. |
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07-23-2023, 10:21 PM | #18 | |
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07-24-2023, 10:29 PM | #19 | |
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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.
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350Z: The Very Poorman's 981 GT4 Last edited by FrostyDC4; 07-25-2023 at 04:53 PM.. |
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