My Octavia TDI 110 has developed a strange noise. I had thought it was the alternator drive belt tensioner, but the noise can't be heard from under the bonnet.

It can best be described as a metallic "tinkling" sound and appears to come from under the car about half way along, anyone got any ideas?

Centre exhaust mount maybe?

Seems worse with the air con switched on, but this could just be because there is more load on the engine and so a little more vibration.

could be your aircon clutch lunching itself - common problem - mine fell off and was in several pieces on the undertray after tinkling for a while.

Check it out, I think you can buy the clutches separate. If the nut holding the clutch is loose it can wreck the splined shaft and then its new compressor time £££.

Here is a link to another similar thread with some info.

http://briskoda.net/octavia-i/air-con-problems-110tdi-slx/87502/

Edited 26 August, 200916 yr by octywagon
found a thread.

Thanks for the good news!

However, the noise doesn't seem to come from the engine bay, you can't hear it from the front with the bonnet open and it is worse with the AC switched on. The poster in the other thread said that the noise stopped with the AC on.

If the weather is fine I'll get underneath for a look tomorrow.

ok, you must have a different tinkle ! - hope its an easy cheap fix.

Edited 27 August, 200916 yr by octywagon
typo

It could be blown baffles in the intermediate box. TO check that you'll need to be able to get under the car and slap the intermediate box with your hand.

I had a similiar issue on my previous car, it was really annoying and took ages to find out what was causing it. It turned out to be the heat shield over the mid section of the exhaust. Two of the metal clips had come off which caused the heat shield to tap against the exhaust.

Still, not sure if Octavias have heat shields around their mid box, or even if this is the cause of your problem. Just trying to think of some possiblities.

It could be; again, it needs access to the underside.

No, I know that sound, it was not that kind of noise.

I have replaced the alternator belt tensioner, which was on my list of things to do anyway and the noise seems to have stopped.

Worryingly, when I turned the pulley on the alternator, it would turn the alternator both ways. I read somewhere that it was supposed to have a one way clutch. Is that correct?

Spoke too soon, the tinkiling is back but it definitely seems to be coming from the exhaust.

Nothing seems to be loose, but if the exhaust is pushed to one side or the other the noise stops. Anyone had this before?

As per #5 blown/broken baffles in the intermediate box. Even Kwik-Krap will charge you nothing to check this!

Thanks Ken, but there is only the cat and then the rear silencer on my car (at least I assume that the front box is a cat). I didn't see ay other silencers unless I missed them.

Thanks Ken, but there is only the cat and then the rear silencer on my car (at least I assume that the front box is a cat). I didn't see ay other silencers unless I missed them.

There is no intermediate box on the turbo models, only the non turbo.

The front "box" is the cat conv and the rear section is the silencer, joined to the cat by a long pipe.