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Discussion Starter #1 (Edited)
Well out of the random, my car started making a humming noise. Was just driving normally and felt a slight vibration in the footwell, specifially on the gas pedal. Turned off the radio and I could hear a humming/vibration noise. Went home and parked the car. Drove it again and noticed it's only really apparent when the car begins to warm up (about 2min after start up). Very apparent around 1500-4k rpm then drowns out. Hopefully it is audible in this video clip. Almost sounds like a bad pulley bearing, but I'm not sure how you'd feel a bad pulley bearing through the footwell.. praying it isn't anything associated with the motor. Rod bearings would knock, bad timing guides I have heard in person and they sound nothing like this, so that basically eliminates two of the major S62 issues right off the bat..

Also worth noting it still makes the sound while revving in neutral and with the clutch pedal depressed. Have new motor mounts, clutch, flywheel, and the trans mounts are 10k miles old. It was doing this before the clutch replacement so that had nothing to do with it. Anyone heard anything like this before? I did countless searches before posting and found nothing, so hopefully someone will have some input.. it's driving me insane. Also I have NO codes/stored codes nor loss of power from what I can tell. Thanks in advance.


 

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Discussion Starter #3
Lol you have to listen really closely. I know what I'm listening for so it's easy for me, but you will hear the noise I'm talking about around 1500-3000rpm. It's a sort of humming noise, not sure how else to describe it.
 

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Sounds similar to what I felt in my 06/00 build right before the drive shaft flex disc/guibo went caput. Slight vibration in pedals, and slight vibration in shifter. Was significantly stronger and louder when cruising down the highway if my foot was off the gas and the car still in gear. Once I pressed on the gas again it would go away. Worth a quick inspection to rule it out. Mine went out while on the highway and caused some major damage, almost 7k in repairs just cause all parts were OEM and some had to be ordered over seas. Thank goodness insurance accepted my claim. Would't want this happening to another beast!
 

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That's engine-related. Sounds like an accessory bearing, like alternator, p/s pump, etc. Maybe the dreaded fan clutch locking up.

Since it's so hard (and dangerous) to listen to each bearing with a mechanic's stethoscope while running, the popular trick is to remove the serpentine belt and run the engine just long enough to see if the noise stops. If it does, identify the bad bearing by spinning them all and listening/feeling for roughness, looseness or binding.

Another possibility, especially as you are feeling it in the gas pedal which would be unusual for an accessory noise, is the oil filter housing buzzing against the driver's side inner fender due to the two rubber mounts collapsing. This was quite common a few years ago but it hasn't been reported for a while now.
 

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Discussion Starter #6
Happens while revving the engine at a standstill so it isn't the guibo. I did run it without the belt but really couldn't get a great impression since I couldn't run it long and of course couldn't drive it...

The oil filter housing is a possibility though. I made mounts for it but I'm gonna check that out tomorrow. It would have to be vibrating real hard to cause all this though.. my idler pulley is pretty loose so I'm gonna replace that. However I just have a hard time believing that would cause an excessive noise like that let alone a vibration through the floorboard. It's driving me insane grrrrrrr
 

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From the video, the noise is very obvious revving to 5000 on the driveway. Why can't you do that with the serpentine belt off?
 

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Discussion Starter #9
If I'm hearing it right is it a slow pulsating hum, sounds like wom-wom-wom-wom?

Sounds awesome with that blower though, damn.
Yessir that's the noise. And thanks lol I do love the sound of the blower, the hum not so much...
 

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Discussion Starter #10 (Edited)
From the video, the noise is very obvious revving to 5000 on the driveway. Why can't you do that with the serpentine belt off?
I did remove the belt but could not leave it running long enough to really tell whether it was still doing it or not in fear of my battery dying/engine overheating... it's really odd. When the car is cold the noise isn't really apparent. After I pull out of my neighborhood for example, I will begin to hear it (about 1/4 mile or so) and once its fully warm it's very obvious. Like I said it's worse around 1500-3000rpm, after that it kinda fades off. When I'm on the gas it's tough to hear as well, WOT I can't even tell it's there. My battery voltage is low while running (around 13-13.7 volts fluctuating) so I bought an alternator from Clemster (best used parts guy I've ever dealt with and luckily he's local :)). Might throw that in today if I have time. However I spun the alternator pulley when the belt was off and it felt fairly normal... we will see. I doubt that's the problem but it would damn sure be nice if it was :rolleyes:
 

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Alright, I'll take a stab at it. This may sound crazy, but I listened a bunch of times, and it sounds like your exhaust is pulsing at some perfect resonance to under a load condition in the range 1750 +/- 200 rpm. You can hear it a little better in the second half of the video when the revs come down and you get back into it. It sounds like it's more or less just drone, but it's hitting an obnoxious frequency that is enough to shake the exhaust and it's mounts under the car, causing the floor shake.

I have no mufflers and am accustomed to drone in that rpm range. Your's is just trying to make music.
 

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Discussion Starter #12
That's a hell of a theory, I'm impressed :cheers:

But it actually seems it was the oil filter housing rubbing. I made mounts for it using materials from the hardware store around the time when I put the blower on (mid september) and it just started making noise. I'm just gonna order OEM ones and hope it goes away for good. What a relief hiha had a feeling it was going to be something small and stupid like this. LOL
 

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That's a hell of a theory, I'm impressed :cheers:

But it actually seems it was the oil filter housing rubbing. I made mounts for it using materials from the hardware store around the time when I put the blower on (mid september) and it just started making noise. I'm just gonna order OEM ones and hope it goes away for good. What a relief hiha had a feeling it was going to be something small and stupid like this. LOL
Ha! I had fun listening to it rev over and over anyway. I had a rattle under the shifter a while back that I thought all kinds of bad things about, and it turned out to be one lose screw in the main splash guard under the transmission letting that thing rattle around a little. Nothing like a little M5 paranoia. The first thought every time is "Oh **** is that my rod bearings!?"


:cheers:
 

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Discussion Starter #14
Lol right, glad somebody understands. All these forums about rod bearings and timing guides exploding and what not gets you real paranoid for no reason haha. Now to just shell out the $30 for the OEM BMW mounts... Ridiculous but oh well it's a BMW guess $15 for a rubber mount with a stud should be expected lol
 
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