Please help. I'm presuming I have a bad pully as our 2013 Mini Cooper S makes a high-pitched, piercing sound upon startup in idle. The attached recording was from inside with the doors and windows closed:

http://drive.google.com/file/d/1-9jn...ew?usp=sharing

The sound goes away upon revving the engine.

I used a spectrum analyzer and found the frequency to be 3575Hz. To figure out which pulley is going bad, I need the pulley diameters, the length of the serpentine cable and the crankshaft wheel diameter. I found the following information. Can anybody fill in the information I could not find and might you have any other suggestions?

idle RPM: 800? = 13.33 Hz
serpentine belt length: 904.6mm (not needed. Just ratio of crankshaft diameter to pulley diameters)
idler pully and belt tensioner diameter: 65mm
alternator pulley diameter: 220mm
waterpump pulley diameter: ?
crankshaft "pulley" diameter: ?

I found the serpentine belt diagram here.

Thank you for your help!

 

Bump. I edited and added additional information...

 

Sounds like the climate control blower

 

Thank you for your help, PEneoark.

 

Hi folks,

I've learned from another post that others have experienced this same issue and pulling the dipstick or oil cap stops the noise issue. Apparently it's a whistle from a vacuum. But the post offers no cause or solution:
https://www.northamericanmotoring.co...ch-squeal.html

I also get a rough idle if I pull either. I also lost two quarts of oil and wonder if this somehow caused it?

Does anybody have any insight into this? Might it be a bad PCV?

Thank you!

 

Hey, I just went through this like a month ago! You most likely have a torn PCV diaphragm. Is your oil cap really hard to pull when the engine's running?

There's a nice write up from @MrGrumpy here with how to and where to get the parts. It's a pretty easy DIY if you're careful with removing the plastic cap.
https://www.northamericanmotoring.co...-question.html

YouTube video of the issue: YouTube video of the replacment:

 

Wow! Thank you GyumDoong! Yes, the oil cap is impossible to remove unless you first kill the vacuum by removing the dipstick. I'll give it a go and post my results. Thank you again! Best to you and MrGrumpy too!!!

 

Yep, the solution from Mini is a new valve cover for $400+. But if it’s only the diaphragm it’s an easy fix. It’s still holding up like new.