Had my old trusty mechanic to have a look at the car today. He was pretty confident the alternator was the source of the sound. He also noticed that the belt tensioner was in bad shape. Might even be that the tensioner is the source of the sound. Didn't ask him if he had the belt off because of the tensioner.
He had some troubles sourcing a refurbished alternator + tensioner but I guess that was due to not having the correct part numbers. Normally he doesn't treat V8's that often
Can someone confirm that the alternator part number is 07 903 015Q and the tensioner 057 903 133J?
I'll see what I will do, maybe I do the job myself depending on what he offers. Looked at the repair guide and it seemed doable in a normal hobby garage without lift.
Can anyone tell if I need the special vacuum tools for refilling/bleeding the coolant system after the job?