High pitched whine when cold at 2k-3k rpm?

[chris719]

Hi All,

I have a Z4M which makes some interesting noises when the ambient is below 50 F on cold start. The idle is normal, but when driving there is a high pitched whine around 2k-3k RPM before the engine reaches full operating temp. Not the normal S54 whine, almost like high pitched diff whine but clearly from the front of the car. It seems to go away as the oil temp approaches 170 F. Any thoughts?

Thanks!

[01SG]

Most likely the idler pulley, tensioners, or something else attached to the belts-could be the water pump, alternator, etc. Try and pinpoint the noise.

Mine was recently making the same exact sort of noise and going away when warm after the car sat for a few weeks. Pretty clearly seems to be the idler.

[sapote]

Remove the belt and spin each pulley to feel for rattle or dry bearing. Fix this or be stranded when the pulley fell off.

[chris719]

Thanks, will probably park it and do all the belts and pulleys. Here’s a short clip where you can hear it. Especially near the end of the clip until I clutched in and revs dropped.

https://youtube.com/shorts/mxgk4PlJW-E?si=gBDMO9cHKImrj84X

[heinzboehmer]

Hmm, alternator is my guess.

Got one that was damaged in transit and the two case halves were knocked out of alignment. Bearings did not like that and it would make a similar noise when spun by hand (I did not install it).

But yeah could also be any of the other bearings n the pulleys/idlers.