B7 A4 2 litre turbo engine noise

[Rotorex]

Wondering if you might be able to point me to a well known fault or common issue.
Last 2 days I have noticed a high pitch squeal coming from either the alternator or compressor pump.
When this happens the engine idle “ hunts” up and down. Sitting higher than it should.
Then dropping down.
Doesn’t seem to be effected by the air going off or on, when the idle is high the squeal is there, when it drops it goes away. It seems to be only if the car has been running for a while.
Does it sound like alternator?
Thanks for any help.



https://www.youtube.com/watch?v=q1vhChtljIk

[ahotboy15]

when the engine is running a long time does it go into reverse easily?

[Rotorex]

Uploaded video

High pitch sound, don’t think it’s alternator now.

Sound only occurs when engine is hot.

Also when I’m accelerating noise goes away, comes back at idle..

[Rotorex]

Anyone?

[Theiceman]

the video is not viewable, you tube likely has some cross country restrictions at play .

take your acc belt off and run it, if the squeeling stops you know its nothing serious.

I have had PS pump bearing squeal in the past. could even just be an idler or tensioner. If you do find it goes away with acc belt off just spin what pulleys you can and see if there is anything noticeable.

Just remember if its your water pump it is driven off the timing belt and if that seizes you are in a world of hurt. highly unlikely to be clutch throw out bearing.

[Denio24]

Interesting though the the revs go up and down. Im wondering if this could be something else all together. I would try to reproduce the issue, then take icemans suggestion and try to run the car briefly with no accessory belt and see if it still happens.

Sent from my SM-G920P using Tapatalk

[Rotorex]

car put up a CEL today but the noise only returns after driving the car for 30 mins or so.
I will have to check the Code this weekend if it lasts that long.

Car has a JHM stage 1 tune also but I'm sure that is not relevant.

Thanks for your responses, I'll try taking the accessories belt off this weekend.

I added a link to the original post to view the video.