ABF Cam belt creeping off

[Boufon]

Anyone got any ideas why my cam belt is trying to work it's way off please?

I developed a "swooshing" noise a week or so ago, took off the belts & pulleys one by one till I had the lower timing belt cover off. Inside the cover there are rub marks from the cam belt & you can see that the belt is hanging off the top aux & pulleys by 2-3mm. It seems to be on the crank pulley fine with no overhang.

I didn't think much of it & put a thick washer behind all three mounting points for the cover to set it out a little. Within three days the noise was back.

The belt is trying to work it's way off & the cover may well be the only thing keeping it on there - rather worrying!!

This is my daily so really need to sort this quick if anyone can help please.

N.B. I had a later auto tensioner on there & have just replaced it with an early manual one (stud & all). This has made no difference.

Any thoughts appreciated!!

Ross.

[VW BUSH]

It means your pulleys are out of line and its finding its own centre.
This could be due to bearing wear in the cam,crank, over tightening, wear on the pulley to shaft mating area's etc etc.
They don't all sit bang in the middle of the pulley once they have settled but if it keeps creeping over and rubbing on the covers you have a problem.
If the belt over hangs you will see a line start on the belt where its not supported, this will eventually shred here making it go bang.

You need to have a good look at all the components/take it to an expert.
How many mile on the engine?

[tweed]

Its a common sound and is the tension pulley.

Also if you over tension it it will try to come off.

[Leon27]

I had this swooshing noise too, only when warm/hot and found it was contact between the cam belt and tensioner. Cambelt cover also had signs of contact. I changed everything with VAG parts and it's been fine since.

If I've read correctly you've already replaced the tensioner so might be an idea to centre everything and run it with the top cover off only and see what isnt running straight, to reitterate what VW Bush said.

[VW BUSH]

Need to be able to twist the belt about 90' at it's longest length.
Swooshing is probs from being to tight seeing as you have put a new tensioner on.
Being tight makes it pull all the clearance one sided on the pulleys causing the belt to skive.
Toothed belts don't need to be tight as its not a friction drive like a pas or aux belt.
Don't drive it around till you are sure.
Two causes for noisy cam belts and that worn tensioner bearings or over tight belt, obviously you can have both conditions at the same time which is where experience comes in.

[Boufon]

Thanks Guys,

Just to be clear, the swooshing noise was definitely the rubbing of the belt on the lower cover rather than bearings or tightness.

That's not to say the tightness couldn't be causing the belt to run off. However, when I first got in there the belt was too loose if anything. With the new, earlier style manual tensioner I have now tightened it until I have between 45 & 90 degrees twist on the longest point.

The noise seems to have gone now but I've only run it today & last time it took a few days for the noise to come back.

I'll keep an eye on it & come back if I'm still having problems.

Thanks again,
Ross.