Aux belt repeatedly going slack

[yossarian247]

Hi all,

This is a bit of an odd problem. Late last year the water pump on my Auris 1.6 Valvematic starting making a scraping/rattling noise at tickover so I got a local garage to replace the pump, and change the auxiliary/serpentine belt at the same time. This cured the rattling noise from the pump, but a few days later the belt began squealing on cold starts. I took the car back to the garage, they adjusted the manual belt tensioner and the squealing stopped for about a month, then came back again. I returned the car to the garage and yet again they adjusted the tension and the squealing noise on cold starts went away for another 6 weeks or so, then returned again! I checked the aux belt (with the old finger/thumb twist method) found it slightly slack, and re-tensioned it myself. Fine again for another month then I was getting a slight 'chirp' on start -up, not as bad as before but noticeable, so again I re-tensioned it!

It seems to be slightly losing tension on it's own in 4-6 weeks. The position of the other pulleys don't appear to be moving, so I can only guess that the belt is stretching? I've changed aux belts on other cars over the years and never had this problem, but then most of them had auto-tensioners which the Auris doesn't.

Anyone else had this issue? Is it just a cheap/rubbish belt that's stretching or something more serious?

 

[crofter]

Nick check the pulley and see if it is shiny all the way down to the bottom of the "V" ? The belt should only be contacting the top half or so and not the bottom of it.                          A good belt will not stretch due to the fibres running inside it.Pulleys are made much lighter now and I suppose it is just possible that an over-tightened belt could cause the sides to open up and give rise to your problem 

Del

[yossarian247]

Hi Del,

Thanks, but the belt is the multi-rib type so the pulley surfaces are flat rather than v-shaped. I'm thinking it's probably the belt, but I've never known a belt to stretch so much and so quickly before. Perhaps the answer is to go to Toyota and get an OEM belt, but for now I'll keep re-tensioning this one and see if it stretches any further. I guess at some point it will either stop stretching,  or reach the limit of the tensioner, .......or snap!

[alan333]

The belt isn't fitted 'inside out' is it by any chance?  Ensure the ribbed side runs on the ribbed pulleys and the flat side on the flat pulleys.

[yossarian247]

Thanks Alan. As far as I recall the belt is fitted the right way round but I will double check.