[Martin Cox]

There's a fairly easy way to check which tensioner is making the noise. Take off the aux belt and start the engine. If the noise is still there, it's not associated with the aux belt but if the noise has gone, then it is.

The aux belt tensioner pulley and idler pulley consist of fairly standard bearings, which are readily available, sandwiched between two shaped steel discs rivetted together. Unhelpfully both bearings are, of course, different.

With care it is possible to replace the bearings. I drilled out the rivets, carefully separated the two halves and removed the original bearings, which after 220,000 miles were a bit rough.

Take care not to distort the steel flanges when separating them. The bearing is glued into the flanges with Loctite or similar. Be sure to use a threadlocking compound on the new bearing when fitting it into the flanges. Otherwise the bearing may move and wear its way through the relatively soft steel of the flanges resulting in the whole thing falling to pieces. When reassembling I replaced the rivets with M5 machine screws with Nyloc nuts. So far I've not had any further trouble.

I do have some pictures which I'll add when I'm next at home.

If the problem is in the bearing that allows the tensioner pulley to pivot and maintain the tension on the aux belt, then this won't solve anything!

Hope this is of some help

Martin
1998 V70 Tdi Auto