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Afternoon,

Right, slightly worried now.. I bought the RS back in May and one of the first things I had done was replace a very worn alternator belt. When I say worn it was held together by a few strands!

So it was replaced with a new OEM belt and I had no problems for the last few months until this weekend I discovered after the battery light coming on and staying on that the belt had in fact completely vanished!

Back into the local Indy it went. He says the crank and alternator are fine but there is slight play on the tensioner but nothing major. Anyway he's put another belt on for now with a view to changing the tensioner after we monitor the belt for a week or so..

However, the plot thickens.. I contacted the previous owner who tells me he had the same issue last year and the car went through 2 belts before he replaced the tensioner pulley and had no problems after that. Whatever the problem is, it's clearly not resolved.

Has anyone had any experience with this?
It's probably worth mentioning that the bottom end was replaced 30k ago at 68k after some sort of piston failure.

The belt is a multiple 'poly-vee' type and due to the size and profile of that form of belt, if theres any mis-alignment between the pulleys, you will certainly get through belts.

I would try and get some sort of alignment check done by your mechanic or make sure the alternator is correctly positioned.
Also make sure the tensioner is in good health with no slack in the bearings etc.

Yes check the tensioner, Audi had some problems where upon it looses tension and allows the belt to slip under load

Checking the alignment is s must too

Ok cool thanks for feedback. Is this a visual check? Or bumper off with some sort of measurement?
Apparently there is slight play on the tensioner but it's a fairly new tensioner as the last one was out of alignment.

ASC wrote:Ok cool thanks for feedback. Is this a visual check? Or bumper off with some sort of measurement?
Apparently there is slight play on the tensioner but it's a fairly new tensioner as the last one was out of alignment.

To do a full check you will need the bumper off,

Your indie guy can check the alignment, if you /indie want to know the full workings of the Audi tensioner give Richard a call at TTS he knows the history of them and what to look out for, good luck

Great, thanks for info mate.

Yep, ive been having dramas with my tensioner too, see previous post. Squealing noises and shredded 1 belt recently. Replaced belt and noticed play in tensioner pulley. Replaced bearing, but still play. Bearing ok, but looks like it has worn its seat on tensioner. Will replace tensioner with new and see how long it lasts.

moondog01 wrote:Yep, ive been having dramas with my tensioner too, see previous post. Squealing noises and shredded 1 belt recently. Replaced belt and noticed play in tensioner pulley. Replaced bearing, but still play. Bearing ok, but looks like it has worn its seat on tensioner. Will replace tensioner with new and see how long it lasts.

Yes would be interested how you get on plus price of the tensioner and what else you find

Since my last post on this thread I've gone through another belt plus new tensioner and the tensioner bracket which had signs of corrosion where the tensioner pivots on the bracket. Apparently alignment is fine.
Just when I thought we'd finally got to the bottom of this problem the battery light came on today and yet another missing belt!! Took it straight to the Indy as he's on my way home but he says he's stuck now with no idea what to do.. The only things not changed are the crank pulley and the alternator. Indy thinks the alternator is Ok.
The belts seem to last a few hundred miles then they varnish like an old oak table!
Has anyone got anymore ideas? Pulling my hair out now, can't rely on the car at all..

Have you thoroughly cleaned the grooves on the pulleys before installing new belts?
Do you regularly drive on a dirt track or a fine gravel track? Check that the undertray is protecting the belt from ingress of water and gravel etc.
Make sure the belt is not being contaminated by oil or coolant.

Is the one-way clutch on the alternator functioning correctly and also check that the de-tuner or vibration damper of the crank pulley is in good shape, and not running out of true, radially and axially (your mech can check this with a dial indicator)

All fairly silly stuff but have to suggest those as theyre the most common causes of poly-vee belt problems.
Heat is a big cause of belt failure, but i dont think thats an issue for you unless the belt is slipping.

Yep, im still shredding belts. Onto 3rd or 4th now
Slight whine under bonnet, intermittent dependent on rpm. not normal. Had tensioner out...again... and think the bearing has been spinning on tensioner seat. Looks shiny on 1 side and definitely not a nice interference fit as it should be. (I used to sell bearings). Bearing is ok.
This problem is taking a back seat for a while as car has been off the road for 6 months, due to DRC failure (90k miles) and KWs fitted last week.
I think I will try and set the bearing central on the seat by centre punching round the seat to create a tighter fit, clean thoroughly with crc brakleen,, then plenty of loctite bearing retainer gear to try and hold the bearing firmly. Leave to set, and remount tensioner.
If that doesnt work, then new tensioner.
Theres a hell of a lot of load on that bearing, the tensioner spring is very heavy.the bearing seat looks to me to be a bit inadequate and doesnt protrude all the way through the bearing I.D. It relies on the hex nut that clamps it tight, to position it and stop it spinning.
I'll try the above next week and see how it goes and post, but I think the problems are related.

Do you have the remains of the belt?
Have a look at this link and see if any of the categories match your belt.
http://www.ero-joint.com/en/micro-v-and ... s-analysis

Check the bottom pulley on the crank,the outer of the pulley has a rubber damper portion which started to separate on mine some years ago after an autobahn high speed run,it had started wobble and run like it was buckled.

Thanks all for the suggestions, that's given me a few things to check. I'll get the bumper off and have a proper look once I get the car back. Up until now the Indy has done all the work so I'm not sure what checks he did when installing the belts and tensioner.
I had a look at that link for belt failures and I only ever found 1 belt out of the 4 that have disappeared and it was pretty well damaged but it was still whole. Looking at those pictures on the link probably the Misaligned one and the Uneven belt wear one are closest to the damaged belt I found.

Does yours have an undertray fitted?
Im just wondering that because you say the belts have disappeared completely.
The remains should fall into the undertray, however, if not retrieved fairly soon, id imagine it would wriggle its way out and disappear.
If the undertray is missing, it might be letting too much water get to the belt etc.