Intermitant whistle during acceleration

[misterkap]

Greetings,

About 2 months ago I began to hear a whirring sound coming from the front of the engine while moderately accelerating through the gears. With that, while cruising, when I accelerate modestly, I hear a high pitch whistle that maintains if I hold the pedal in its position, but goes away if I accelerate harder or let off. I have since REPLACED THE ALTERNATOR BELT, TENSIONER, AND IDLER PULLEY as I was convinced it was one of the two pulley bearings going bad. I am 99% sure that this noise is due to a dry bearing given its characteristics of frequency, pitch and operating circumstances. The whistle can be heard during idle (sometimes) and has since gotten a bit worse so it is always apparent during acceleration.

Now, I have read about alternator pulleys sometimes having a overrunning bearing/clutch assembly, but cannot determine whether our S4s have this or not. Can someone please clarify? If these alternators do not have this overrunning pulley, has anyone experienced the same issue? Is it possible that the bearings in the alternator are bad? Any other suggestions as to what this could be?

Thank you in advance for advice!

[Sphawkins007]

I just replaced the Pcv valve for whistling. Look into it as atleast it's pretty cheap and easy fix

[hkdolphins]

I just replaced the Pcv valve for whistling. Look into it as atleast it's pretty cheap and easy fix

Yes, same to my fix, the PCV went bad (whistling at the back of engine when accelerate) right away after valve cover gasket job.

[misterkap]

I've seen videos and sound clips of the PCV whistle noise and it doesn't sound similar. I know the noise is coming from the serpentine belt area because its very loud if I listen near the passenger headlight. At this point I'm pretty sure the alternator has bad bearings or is vibrating at various RPM, I just want to be sure before buying a new one.

Can the alternator be taken out without pulling the radiator off, and just putting it in service mode and lifting the car?