My Citroen XM 3.0 PR-Vestige

[Dean]

The bolt is OE Will, i can get the belt very tight to the point where there is a little deflection in the pump mount plate itself, the hydraulics work fine it's just the belt slips during use.
It could not back out as there is the tensioning bolt mechanism that acts on the rear rocker cover so even with a loose locking nut it can't slacken the belt off.
I have the car back together now with just a couple of difficult to reach pipe fittings to tighten.

D

[White Exec]

. . . however I might add another bit of studding sticking out at right angles, to allow a nut to be used as a tensioner as well as locking the original studding from turning.

Quite a few alternators have something like this, to maintain belt tension for the small diameter pulley.

[White Exec]

Space for twin pulleys and belts, Dean?

[Dieselman]

If I add a tensioner bolt, I wouldn't add it at the end of the bolt ala Citroen. I will weld a stud on near the pump bracket, so it acts directly on it, not at the far end of a 4" long bolt.

I have found the way to tension these pumps is to use a lever under the pump bracket itself. If tension is applied further away, the bracket bends so there isn't proper belt tension.

EDIT.

I have just come across a technical bulletin and see I have the above information wrong. The tensioner bolt is supposed to be positioned at the pullet end of the bolt with the locknut at the opposite end. The Citroen parts diagram has this reversed.

I have a plan.

p.s. the belt should be 670mm for the 100 mm pulley.

[Dieselman]

Dean,
might a belt tlike this be useful to you? Apparently it can transmit more power than normal...

http://www.bearingoptions.co.uk/v-belt- ... 0548-p.asp" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

Are your belts definitely 10mm x 670mm? If they are narrower they will not be able to transmit as much power and will move down into the pulley v and wear rapidly.

The one on my car is chirping again and I'm sure the tensioner bolt hasn't moved, but the belt is wearing thinner.

[Dean]

Which belt Will?

Ive looked at a few and i have options, you have the cit doc now but yes the tensioner bolt seats down on the lug cast into the rear rocker cover and you jack the bracket up using that then lock it off with the rear 13mm nut on the A/C side of the bracket which is part of the tensioner.
My belts are 10 x 670mm yes, after my initial fumblings with incorrect length i sussed that out, i have just fitted my last solid belt and it seems to be fine with no slip but i've had this before.

I a bit disappointed there isn't enough room to easily add a double belt setup, i am toying with the idea of pressing the 100mm pulley off and having a go with 130mm pulley or nearest size, the belt only slips on the smaller pump pulley (well it would being smaller) i think the larger pulley could give enough extra grip to solve the issue, either that or the pulleys have worn out or become contaminated, they have been coated with brake cleaner again just to be sure.

With you suffering this problem too im convinced the rive design/gearing is just too borderline, what on earth was the smaller pulley like?.

Anyway, she is mobile and working again with no leaks so i will wrap it up and get ready to clear off on holiday.

D

[Dean]

Got it, look like normal belts with extra marketing BS but, i have just ordered two with 48hr delivery, should be here Wednesday and i will take a look, i need a spare anyway.

D

[White Exec]

That 'cogged' belt doesn't look anything special. They're stocked as a matter of course by motor factors here, particularly for small pulley applications. It's 70degC upper rating isn't too generous either. My engine bay regularly tops that.

As Dean says, really important that a V-belt accurately matches its pulleys. Should properly 'fill' the vee, going right up to the top (ie not be too narrow, and have the correct taper). Cogged/toothed a good idea on small pulleys, as it helps the belt sit 'down' - and run cooler, as they flex easier. It's all about maximising frictional area with the pulley sides. Vernier caliper time...

Pump/alt tensioning bolt must exert its support/thrust on the pulley side, as close to the pulley bearing as possible. Otherwise there will be a tendency for the pump/device to twist/flex/vibrate under load.

If twin belts are really not an option, how about swapping the V-pulleys for ribbed ones? Citroen did this, and for good reason.

Just glad originality here isn't requiring hanging on to dynamos and mechanical fans! Sometimes, it is better to modenise, done discretely.

[Dean]

Looking today it could be possible with some fettling of the matrix pipes brackets and some bending to fit double pulleys, the belts could then be run at a sensible lower tension with no risk of destruction, it would be close though, in terms of space, i think fitting a larger pulley to the pump would do the same thing if fluid supply is acceptable for steering supply at idle, a ribbed belt would be better and suitable ribbed sprockets could be sourced from scrap vehicles.

D

[White Exec]

A ribbed belt has got to be the tidiest solution, assuming the right sizes can be found.
Would also be a good (and reversible) test-bed project, which others could find useful, especially if standard bits can be used.