Xantia Auxillary Belt Tensioner

[AceTinker]

Can anyone tell me why the M12, 10.8 grade HT bolt in the Upper Tensioner Pulley should snap?

I'm afraid the story is quite a long one ....

August 2008 : Auxillary Drive Belt broke. I fitted a new one.

4th December 2009 : Belt shredded as the car warmed up. RAC did a roadside repair but were unable to tension the new belt sufficiently.

9th December 2009 :New Belt started to shred. RAC thought this was because upper tensioner was not running true. Took car to garage where they fitted a new belt, upper tensioner pulley and spring tensioner for £328.

January 2011 : Whining noise from engine led me to look at the Belt which had freyed and the bolt through the Upper Tensioner Pulley which had snapped. Took it back to same garage. They thought the bolt sheared because it had worked loose, so when they fitted a new one + pulley, they secured it with a type of thread-lock. Total charge, including another belt was £308.

February 2012 : A rattling sound from under the bonnet led me to a loose Upper Tensioner pulley, where the said bolt had sheared just like before.Back to same garage where they reluctantly repaired it once again. This time I insisted that they use all genuine Citroen Parts, so the fee rose to £442. Even so, they would not give me a guarantee, as they said my car must have "other issues".

According to an internet forum I read, these belts can brake when the hydraulic pressure is too high, and that this can happen when the hydraulic filter gets clogged. So, since February 2012, I have cleaned these filters twice and replaced the old hydraulic fluid with new.

The only other precaution I have taken is to purchase a long extension lead and a hair dryer, which I will dangle into the engine compartment on freezing mornings to warm the belt up and make it more flexible. What else can I do ? - any suggestions will be gratefully received.

[citroenxm]

From what it sounds like your car is a Late R reg S1 to later 1999 TD with the awfull spring loaded tensioner that is renoun for wearing the needle rollers in the base of it... Your garage was right to replace the tensioner when they said the pully was not true in line-ment.. however for you to have further issues is a strange one... One possible thing is that the belt could still be TOO slack... There is also an eccentric tensioner, accessable through the wheel arch.. It has an 8mm allen bolt, and a square hole in it. The idea is to fit the Aux belt in the correct sequence, then tighten it up with the eccentric.. The spring tensioner then keeps it tight and takes any flap slack up... There is different rates or length of spring (the one behind the HP pump).. Also, the Bush Spacers in each end of the Spring behind the pump wear away and get battered to death on a rattley belt... Did they replace the spring and bush's?? The spring ends should be a snug fit on the bolt shafts..

This setup was only used on the TD Engines from around late 1997 to end.. The HDi uses a much more reliable and easyer to use setup...

But, apart from a slightly slack belt I cant think of anything else.

Does the belt "Flap" at idle between the crank and Air con pully? The noise also sounds like a low "rumble" which disapears when the revs are lifted.. If so, its too slack. Have a look at the eccentric.. Its fully tight when the square "hole" is on the crank pully side...

Ive Never heard of a belt breaking due to excessive hydraulic pressure, the regulator on the front of the engine/gearbox deals with all that, which is after the pump in the system..

[Xaccers]

First thing I'd do (if I was in the position of having to use a garage) is find a different garage! Those prices are ridiculous!
Do you know what length belt they fitted? There are several that will fit depending on what type of A/C compressor you have (different compressor pulley sizes).
Another thing to check would be the state of the crank pulley as the outer section can separate and start to slip. To check, just paint/draw a line across the black rubber ring on the face of the crank pulley. If the outer part is slipping the line you drew will break.

Now I've had the bolt snap once and that was after using a tensioner from EuroCarParts, wasn't impressed. I've always used GSF since then.

[AceTinker]

Thank you both for your comments.

You are right about my car -it is an R-Reg, 1998, TD, 1.9L. I don't think my belt is slack - there is no sign of slackness and no rumbling on start up, but I will keep an eye on this as I could see how a slipped belt could cause the tensioner bolt to shear.

The belts fitted have all been GMV61738 apart from the last one which was a Genuine Citroen Belt, 6PK1740.

I assume the bushes to part of the spring tensioner assembly which was replaced as a unit. But Xac's last comment was very interesting, as I'm almost certain the garage fitted a Unipart spring tensioner to mine, and it is only since then that the bolts have been shearing. So, with this in mind, I have just sprayed the tensioner with with oil to aid it's lubrication.

With regard to the hydaulics, could a faulty pressure regulator be to blame?

[citroenxm]

No, not at all...

The Springs bush's are a tight fit in the "eyelet" holes each end of the spring, BUT can and do fall out while trying to fit it in place...

[jgra1]

wonder if the belt is just too tight all the time? i.e. the eccentric tensioner is set wrong..or the belt is a couple of mm too short..
either way a horrendous tail of unreliablilty and expense, Ace

I cant believe an overpressure of the hydraulics could cause this either.. (is there a warning light for this anyone?) but surely the belt would just screech away and snap?