Auxilliary Belt Problems...still!

[Little&Large]

Hi all
Help needed desperately!!!I will describe the problem briefly.My car last year had 2 auxilliary belts replaced in the space of 6 months.When I bought the car the belt was very noisy and quite loose.On investigation the spring tensioner device was missing(deliberately?).This was replaced and all appeared to be well-the belt was tight and the noise stopped.I am due to go to France tomorrow and had a look under the bonnet yesterday and noticed a score mark around the belt approx 3-4mm in from the right hand edge of the belt(with the white cord showing in it).(It looked as though someone had run a stanley knife against it whilst moving).The groove was on the outside of the belt and not the ridged inner side.This got worse today and so I went to the XM garage and on the way the 3mm strip came off and the remaining belt seemed to centre on the top pulley.
The a/c was regassed on Thursday and I have had this on all the time over the weekend.(but I don't think it was working last year though).
Anyway the belt was replaced with a new Citroen belt today and after a thorough examination,the mechanic could see nothing wrong with it at all.I tested it up and down the dual carriageway and all seemed well.I left with the a/c on again and on stopping a very faint line is starting to appear again.I turned the a/c off and can't decide if it has not got worse having switched the a/c off.Something must be rubbing very slightly against the belt to do this,but we could just not see where!When I touched the belt and pulley it did seem quite hot,but on a day like this it is hardly surprising.I don't think the a/c has worked for a long time,but after the re-gas it appears to have worked very well.
Does anybody have any thoughts or idea?
Many thanks
Regards Rob

[noz]

Hi Rob,

I know you'll probably not want to hear this but I can only suggest the basics:

Working on the basis that the damage begins on the non-ridged side and works its way through:
The belt is only in contact with the pulleys on the ridged side so that rules out the crank pulley, A/C pump pulley, alternator pulley and HP pump pulley. When the belt goes around the tensioner and the idler it touches the back (non-ridged) side of the belt. There's your first possibility. Put your finger on an accessible portion of each pulley in turn and have someone turn over the engine with a socket and ratchet on the crank pulley (not whilst the engine is running!). Make sure both pulleys turn through at least 360 degrees and are smooth to the touch all round. Next trace every inch of the belt around its entire circuit with a torch. Some of the belt is difficult to get at so use mirrors if you have to. Get a good strong light too. You're looking for something just fouling the belt and no more. It could be the edge of the plastic shroud or the metal bracket of the tensioner. Something somewhere is touching that belt. Look for belt fragments around the protrusion which is causing the cutting action.

Last straw, working on the basis that the wear starts on the ridged side and works its way through:
Try running the engine with the A/C both off and on. I know it will be difficult but try to assess whether or not the A/C load on the A/C pulley is causing the pulley to stop under load. Try switching the A/C on and off whilst closely observing the pulley. Does it appear to be slipping?

Hope that helps or leads to further inspiration. Let us know how you get on.

cheers

noz

[Little&Large]

Hi Noz
Many thanks for the reply.It is interesting that you mention the tensioner-the mechanic put slightly thinner washers on the tensioner bolts when he fitted the new belt this time.The line appears to be 1mm closer to the edge of the belt this time-so it could be the tensioner it is catching on.
I will speak to the mechanic tomorrow.
Thanks again
Regards Rob