'98 Xantia 2.1TD alternator-belt auto-tensioner

xantiadave · Post by **xantiadave** » 01 Dec 2006, 10:15

Hi all,

After cresting some large bumps on a boggy road recently in the west of Ireland, I later heard a knockin sound from the engine which turned out to be a thin section flailing off the auxiliary drive belt. When it came to putting on a new belt, I could not push back the auto-tensior (by engaging a square-end tool in the socket and turning clockwise as described in the Haynes manual), so I just tightened the manual tensioner so that there was 5mm or so of give in the longest stretch of belt when pressed with a thumb.

Question: Is a broken (appears fully-deployed) auto-tensioner likely to have caused the belt to have slipped sideways and fray in the first place (perhaps due to over-tensioning), and, if so, will the same happen to the new belt even if the manual tensioner is used to tension the belt approximately correctly?

I have read elsewhere on the forum that it is a longish job to replace the auto-tensioner as the hydraulic pump needs to be removed. Would it make sense to incorporate this job into a rare garage visit when the engine will need to be taken out for a new timing belt? If so, is it safe to leave for another 6 months or so as is, when I intend to change the timing belt (120,000 miles on the clock, bought at 95,000 with markings indicating timing belt changed at 72,000). Having driven over 500 miles like this so far, the belt seems fine.

Any thoughts?

Dave

Post by **RichardW** » 01 Dec 2006, 12:13

It could be that if you bounced it over a big bump the belt flapped and pushed the tensioner out, causing it to jump sideways. I doubt it's easy to tell if the new belt will go the same way - just keep an eye on it. I think you have to remove the mounting bracket to change this tensioner, so it's a bit of a job.

Not sure why you think the engine needs to come out to do the cambelt - the head yes, but the cambelt no. If you do tackle it, make sure you do not overtighten the retaining bolt on the tensioner - it has a very low torque setting and the bolt shearing a few 000 miles after the cambelt has been changed is not unheard of.....

xantiadave · Post by **xantiadave** » 01 Dec 2006, 15:33

Hi Richard,

Thanks for the reply. Sounds like I should just keep an eye on the new auxiliary drive belt then.There are no unusual sounds from it anyway, and engine running better than ever (50 mpg on last tank), so that's reassuring.

As a novice mechanic, and having read about the risk and consequences of putting a new cam-belt in slightly mis-aligned elsewhere on this forum, I think I will probably leave the cam-belt change for a garage when it's due (though fear the cost).

Dave