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      09-15-2021, 10:27 PM   #1
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Replaced valve cover and I still get that distinctive squeal. What now?

I was getting that very distinctive squeal that's the hallmark of a bad PCV valve. Just like every description, it would go away when opening the oil fill cap. I replaced the entire valve cover and it's still making that sound! If it's not the stupid expensive fix for the PCV them what could be causing this?

Edit to update: Replaced the valve cover again, also replaced the crankcase vent hose, and the squeal went away. If you're replacing the valve cover I'd recommend replacing the hose as well. I cut the insulation off my old one and the hose inside was cracked and came completely apart with very little flexing. https://www.fcpeuro.com/products/bmw...mw-11127850244

Last edited by Tangent; 10-10-2022 at 11:58 AM..
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      09-16-2021, 06:19 AM   #2
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Do you hear it louder under the car?
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      09-16-2021, 09:41 AM   #3
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Yup, it seems loudest in the right location to be the rear main seal making the noise. But with the PCV valve replaced there shouldn't be an overpressure making it do that should there? Or are they known to get damaged quickly enough from that that even normal pressures will do it afterwards? I'm hoping there's something else still causing excess pressure that can fix this without the labor involved with replacing the RMS...
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      09-16-2021, 09:54 AM   #4
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Quote:
Originally Posted by Tangent View Post
Yup, it seems loudest in the right location to be the rear main seal making the noise. But with the PCV valve replaced there shouldn't be an overpressure making it do that should there? Or are they known to get damaged quickly enough from that that even normal pressures will do it afterwards? I'm hoping there's something else still causing excess pressure that can fix this without the labor involved with replacing the RMS...
RMS is were I was going with my question. If the damage is done you will get pressure leaking there. Take the covers off and see if you see any oil leaking where the tranny bolts up.
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      09-16-2021, 12:36 PM   #5
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Quote:
Originally Posted by rmanm4 View Post
RMS is were I was going with my question. If the damage is done you will get pressure leaking there. Take the covers off and see if you see any oil leaking where the tranny bolts up.
I'll check that out. With a properly working PCV system would there still be enough pressure in there to cause that squeal though?
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      09-16-2021, 12:39 PM   #6
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Originally Posted by Tangent View Post
I'll check that out. With a properly working PCV system would there still be enough pressure in there to cause that squeal though?
I have no idea. I know for a fact that a bad PCV will pop open the RMS. If you fix the PCV will the RMS seal back up?? No idea! Get under the car and take the covers off, you will know right away if you see any oil stains (wet or dry) between engine block and tranny!

There is also a seal around the crank hub on the N55, but im not sure about the S55 (too new to me). I've never heard or seen that seal go due to PCV, it usually goes when the main belt slips off and shreds into the engine thru that seal.
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      10-09-2022, 05:48 PM   #7
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I am having the same issue. Did it end up being the RMS?
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      10-10-2022, 11:56 AM   #8
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Quote:
Originally Posted by Mnguyen600 View Post
I am having the same issue. Did it end up being the RMS?
I think what actually finally fixed it was replacing the crankcase vent hose on the front of the valve cover. I replaced the valve cover itself again (gotta love FCP Euro's warranty) but also replaced the hose and the noise went away. When I cut the insulation away from the old hose the inside was cracked and came completely apart with very little flexing.

https://www.fcpeuro.com/products/bmw...mw-11127850244
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      10-10-2022, 01:05 PM   #9
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Quote:
Originally Posted by Tangent View Post
I think what actually finally fixed it was replacing the crankcase vent hose on the front of the valve cover. I replaced the valve cover itself again (gotta love FCP Euro's warranty) but also replaced the hose and the noise went away. When I cut the insulation away from the old hose the inside was cracked and came completely apart with very little flexing.
So the squeal was coming from the crack in the hose, under the insulation sleeve??? Good find!

Gotta add that to the find-a-squeal checklist.
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      10-11-2022, 12:06 PM   #10
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It wasn't coming from the crack, I think the fact that it was cracked was causing the PCV to not function correctly so it was still squealing from the RMS like a failed PCV valve would. I suspect that at least some PCV failures are actually caused by this hose cracking.
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