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Hey so I recently bought a 00 m5 with about 120k on the clock. Isn't in great mechanical condition but it runs. For starters the passenger window regulator was shot, the clutch was slipping, the guibo is on its last legs, driverside cat is cooked and it has the and worst of them all the emissions system is clogged with carbon. I can live with and fix all of these issues as I have most of them, I already did the clutch and flywheel myself and it's not a fun job if you don't have a hoist. Anyways, car makes great power and I have no codes other than SAI and the fuel tank breather valve which isn't a big issue.

The car started to make this high pitched cyclical dry bearing type noise that I can't figure out what it is. If anyone has any idea what it might be here is the video I took

https://youtu.be/4eczXDOVnGg

Sorry for quality but the windows are down. The weird thing is it mostly only makes the sound if there is enough stress on whatever it is making the noise. What I mean by this is its not related to engine rpm but by load. So if I'm in 6th at 1500 rpm and I put my foot fully down you can hear it, it's not a high pitched squeal tho at lower Rpms, it's sort of a different sound so Rpms determine the pitch of the sound.

I can drive the car pretty easily and even Rev it to redline and it won't make the noise as long as I'm not putting too much torque through it. Also it will make the noise if I coast in neutral and Rev the engine. Most of the time it doesn't do it when I'm stopped and start revving it but when it does its very slight. It's not the csb as I thought before I did the guibo and checked it. Also it happens in neutral sometimes so naturally it can't be. I was thinking it might be the alternator bearing as when I cold start the car up can hear it kind of howl until it warms up. Couldn't find any posts that are similar to what I'm experiencing so thought I'd throw this up before I go ahead and replace all the pulleys and alternator.
 

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Could it be the engine pinging (detonating) under high load? I can just hear a very light rattle in your clip. These cars will give a quick ping when the throttle is snapped open in neutral as well. Search for "detonation" or "pinging". There have been a couple of threads recently.

By the way, it's not a good idea to floor the gas pedal at 1500 rpm in any gear but especially in 6th since the revs stay lower for longer. It puts a very high load on the rod bearings before the oil pressure is fully developed. Safer at 2000 or more.

Malcolm
 
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