Hi there I have this horrible squeal which sounds like it's coming from the aux belt area. I have recently replaced the aux belt tensioner and the aux belt but I still have the squeal. It's only on start up and while the engine is warming up then it goes away. Any ideas?

I had that on my old Passat and I just considered that it was the aux belt tensioner pulley bearing.  So, in your case that just leaves any other pulley bearings - including the alternator?

Cam belt idler pulley? You don't say which engine you have which makes it much harder for us to help you.

It's a sdi 1.9 

Still have the same problem and changed the belt so it's had a new aux belt tensioner, 2 no. aux belt and the squeal still persists. It also now has a 'tsh tsh tsh' kinda sound which is very faint but can be heard. Is there anyway to check the alternator pulley or what else could be causing this? Could it be a result of the timing belt?

1 hour ago, MrSissons said:

Still have the same problem and changed the belt so it's had a new aux belt tensioner, 2 no. aux belt and the squeal still persists. It also now has a 'tsh tsh tsh' kinda sound which is very faint but can be heard. Is there anyway to check the alternator pulley or what else could be causing this? Could it be a result of the timing belt?

I have also got this issue as of yesterday. Brand new aux tensioner and belt about 3 weeks ago. Doing my head in, horrible noise.

Well, just after engine start up from cold, the battery will require quite a bit of re-charging, so, as I said before, if the alternator bearings are getting on a bit, they might just be making a bit more noise than normal when that alternator is being asked to do more work, plus if that battery is getting on a bit, it will be asking for more in the way of charge than a newer battery would under the same conditions.

 

So, before going to bed, remove the auxiliary belt, then early next morning start that car up, if there is no nasty noises, you can at least consider that it is coming from the auxiliary belt driven bits? (maybe not the best way to start the day, ie needing to stop the engine and get that belt back on etc, but if you are truly interested to sorting this out, doing that might help you.). If that noise is still there, then you better get the cam belt area looked at sharpish before it causes you more pain.