TDI150 Strange sound from ancillary drive belt tensioner?

[BoraTDI]

First off thanks for looking at this thread.

My 03 plate Bora TDI 150 has developed a very annoying rattle, at idle power there is a pronounced rattle that is most audible in the car, if you pop the bonnet it can be heard outside but with the bonnet down its very discrete, needless to say very annoying in the car. The rattle immediately stops if I touch the throttle to get 1000rpm and occasionally the rattle will stop if I either a) turn off the aircon/heated rear window or b) sometimes turning on the heated rear window will stop the noise, basically changing the load on the engine changes the rattle.

Another sound which I am sure is related is when I attempt to turn the steering wheel whilst stationary ie. when parallel parking, the rattle turns into more of a squeak which is in rhythm with the engine revs, when I get to full lock the squeak is actually unbearable as a very high pitched belt rubbing kind of noise. By looking and listening under the bonnet the sound is coming from the ancillary drive belt tensioner area though I cannot be sure. The final piece of info which may be useful is that when looking at the drive belt tensioner it moves an awful lot when the engine is running, is that correct? shortly moving like it does is always changing the tension of the belt?

Thanks very much to anyone who has a clue what may be causing this.

By the way the cambelt was changed at 60,000 miles by VW and its now approaching 85,000miles, other than that it has been serviced by the main dealer every time and on schedule.

[BoraTDI]

Looked at the car again this morning and noticed that the ancillary drive belt is beginning to crack up, also the tensioner seems to be near its stop, could this be indicating that the belt is stretched which is why the tensioner is perhaps not applying full pressure to the belt? This would also indicate where the squeak comes from at full lock as at that point the power steering pump is taking the greatest load so perhaps the belt is slipping a little? the squeaking sound is very reminiscent of fan belt squeak although much more intermitent.

The belt has actually never been changed and the mileage is getting on a bit so I'll change that and see what happens.

[Boy]

Hi, Are you yet able to tell us what happened when you changed the belt tensioner?

[BoraTDI]

Sorry for the long wait for a reply.

Well I managed to change the tensioner and I changed the belt whilst I was there and the squeak disappeared for a good few weeks, however it is now back and just as bad.

The rattle I fixed and noticed that I had a broken support bracket on the engine, repaired the bracket and the rattle disappeared, just cannot get rid of the squeak.

Any idea if one of the ancillaries is perhaps wearing out? The car has 98,000 miles on it now, could it be the power steering pump or Air Con. compressor that needs an overhaul?