[!!] Need help diagnosing possible engine issue - December 07 build E92 M3

[Seattle S65B40]

Hello: I hope everyone is well. I have been busy as hell and have not posted in forever, but this one issue keeps popping up randomly and I figured you guys would know, if anyone.

I cannot ever get it to occur for the service techs so I need some help figuring out possible causes to make my case to the dealership to investigate this potential problem. Please listen to the two comparison sounds I've posted and let me know your thoughts (crappy iphone video but should be able to notice the difference).

Summary of the issue:

Dec 07 build 2008 E92 M3 6MT 34XXX miles

As of a couple thousand miles ago, i would randomly get this strained, moaning sound from the engine after a spirited drive.

At first, it always seemed to kick in after the downshift i normally make near my house from 3 to 2. This shift is sometimes performed around 3500-5000 RPMs depending on traffic patterns (fun little back road when no one's around). After that, it's not far to my house. I can noticeably hear that sound from after the downshift until i pull in the garage and shut it off. The next time I turn on the car, it's fine.

Lately, it has increased in frequency and occurs in the absence of the downshift, but randomly. It seems to be performing fine otherwise but need to know what's up. I'm sure it will appear while I'm near a dealership eventually, but my concern is that it could be more serious and should be checked out before it gets worse.

Closing Remarks:

Overall, i wonder about the long term durability of this car. It was among the first produced and just doesn't sound as crisp as it used to. My warranty is up in June and this could force my hand (was hoping to ride this horse until F82 M4 hits).

On the other hand, the car drives fine otherwise when this noise is present and it could be a quick fix. Aside from this issue, the car has been virtually problem free (Cowbell excluded ) and performs very strongly at this mileage. It's still a dream to drive.

I welcome any commentary on the oft-discussed, yet always relevant, issue of durability so long as at least a few people stay on topic and help get this figured out! haha

Videos:

You'll notice it most when I lightly rev it in Video 2. If you guys can help out, i would really appreciate it. Thanks!

Normal:

Strained (listen closely at the point of light revs):

[bmwm4f82]

Did you have all the same settings, ie Sport mode on / off in both?

[Seattle S65B40]

Originally Posted by bmwm5e60

Did you have all the same settings, ie Sport mode on / off in both?

yep. Happens irrespective of power setting. Thanks for raising that.

[SenorFunkyPants]

Sounds fine...if there is something wrong then it will get worse soon enough then you will have no problem hearing it!
Don't fret - engines make all sorts of weird noises - if there was something serious then @8400 rpms it would soon rip itself apart.

[M3PO]

I'm having a hard time hearing the difference. Have you checked the power steering fluid?

[stefan]

I too am having a difficult time hearing anything definitive.. maybe sounding a bit more metallic or raspy in the second video.. hard to say. Doesn't seem like it's a problem, yet.

[alpina527]

Have you checked the auxiliary belts? Try spraying a bit of wd40 on them to see if the note changes

[nickdrivesm3]

I heard it. That sounds just like a power steering pump with low fluid.

[BPMSport]

Yup it does sound like a low power steering pump..

Not saying thats it but the noise is certainly a match.

[Seattle S65B40]

Great. Thanks, guys. I will take that back to the dealership and see what I can get them to do.

Pardon my ignorance, but is there a quick and easy way I can check the power steering fluid level?

Thanks!