Hey, everyone!
I bought my E90 3 months ago and finally got around to installing an aftermarket downpipe last night. It was pretty tough and took me about 10 hours (lol). I let it run for a while and tried to check for leaks before leaving the shop, did a test drive, went back, let it run for a bit longer. Everything looked and sounded good as far as I could tell. Of course, as soon as I start driving home I start hearing this: EARFUCK WARNING! https://youtu.be/3hrt61FqzW0. (Ignore the chirping in the background; those are crickets lol). I honestly thought it was some kind of siren coming from the nearby airport at first.
From my research, the only videos I could find with similar sounds seemed to be diagnosed as failing PCV systems. Is it possible that the increased flow from the new downpipe caused the PCV system to fail?
I went out today and tried to re-create the issue but it didn't occur during the 15 minute drive. Maybe it didn't reach operating temp, idk.
Anyone have any further knowledge of this issue?
Last edited by MozartE90; 05-24-2020 at 12:28 PM.
When it's making the sound loosen the oil cap if it was pcv related the noise should change or go away
Thanks for the reply. I'm going to try that when I'm able to replicate the issue. Is PCV noise usually something that comes and goes? I just drove for 20 minutes straight and no sound came up.
N55,m so 335. You messed with the exhaust not far from the turbo. The noise went away, so maybe it was a one-off kind of thing. But the sound seems like a dry bearing, that kind of thing. It would suck if the turbo locked up.
As far as I can tell the car feels pretty much the same as it did before. I drove it a lot today and didn't have any issues. The sound was so loud that I'm surprised it isn't something that's popping back up.
Sounds like it's time for a new valve cover.
ASE and BMW Master Certified Technician
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