Citroen XM Forum

H all.

I recently changed my accumulator sphere, to see if it would stop the hissing from the front on tick over ! not sure wether to change the front centre & rear centre sphere now !, or could it be the pressure regulator ,
When you slightly turn the steering the hissing stops, now what is the best thing to do ???
The car came back from Geneva, and had just had a fare amount of money spent on it at a Citroen garage out there,on the rear, so i quess it should all be ok ! although the rear ones look fairly old they do give a comfy ride, so do you think i should change the centre one's ??,

When pulling away quite hard the back drops, and there is a slight delay before it rises back agian, meaning it's only a few seconds or so , is this normal ?
Having had the Xantia before , and changed the accumulator sphere on that one, when switched off and you sat on the back , it leveled itself quickly, the Xm doesn't , and takes upto 5 mins to rise,
If i were to change these spheres, are they classed as a normal sphere, say that you would put on the corners, or are they differant ??
Sorry to sound a bit in the dark over this, but i'm learning about the Xm, and there's bloody spheres everywhere ,
The front two spheres do look fairly new, but feel after having the Xantia, it could be a little softer on the front end.

Any advice guys

NIgel

The rear should sink readily on pull away but rise after a second or so. If it's failing to rise when load is added you have a sticky height corrector.
A test for the spheres is to bounce the car up and down with the engine running, in soft mode. There should be significant movement at the rear, less at the front.
Try flushing the system, mine has definitely become more supple and I had changed all the spheres as well, but it wasn't instantly supple.

This hissing is quite a common fault due I think to the pressure not reaching the cut out point at tickover, probably caused by general hydraulic system wear.

Peter

The hissing is caused by the peice of junk low pressure Poogoe steering rack fitted to the car. Try moving the steering wheel a small amount .... and the hissing will stop. If I had my way I'd throw the steering rack and it's garabage associated plumbing away and fit a proper Daravi rack............ It's far more involved than it sounds though. You need to centeripitle weights unit/valve, the cable drive for it and the daravi controller (steering column).

seeya,
Shane L.

..... I think I will put up with the hissing - diravi would be very nice though.

Citroens are meant to hissssss.... its part of the Character of the cars!

Its defeantly steering related as shane says, as Xantias after 1994 haven't got a Flow divider and dont hiss - also, S2 XM's from around 1996 also had them removed.. Ive a customer with a 1996 XM Estate TD, with Mechanical Injection, and No Flow divider, and anti sink.. so hissing there..

Paul

My BX made the constant Hisss, it had a flow divider valve. It would stop if I moved the steering wheel a bit or revved the engine whereupon the regulator cut out.

The fault is certainly with the FDV itself as I initially suspected a worn HP pump not delivering enough flow to feed the FDV and the PRV, brand new pump, belt and LHM, new filters and 5 new spheres and the result was a marked improvement in ALL systems of the hydraulics EXCEPT the hissss which got marginally better in that it still did it but instead of going on forever it actually did eventually stop on its own without any steering movement or anything (only for it to start doing it again as the first press of the brake or suspension demand)

Anyway, process of elimination says it is the FDV unit. I outlined the strip down over on the BX Club. I identified the phases of operation of the FDV via the workshop manual and understand how it works and what it's doing on each phase (essentially giving a continuous LHM flow to the steering regardless of cut in or cut out of the PRV whether steering or not) but I never identified which was the actual 'hissing phase' as such and hence, can't be certain what bit of the FDV hisses specifically and what part has gone out of kilter so as to hiss constantly at idle (lowest LHM supply flow). I suspect that it is caused by one of the FDV's 2 springs being weakened due to age but can't verify this properly now that I am BXless.

Needless to say DSs, CXs, GSs and all post FDV Xants and Xms do not suffer from this as stated above.

If I still had the BX, I'd strip and rebuild the FDV (relatively easy) and replace the springs with a very slight stretch to their length to see if it improved it.

DS's not got an FDV?? They have PAS, so what did they use on them??

Its not DIVARI either..

I thought anyway..

Paul

citroenxm wrote: Its not DIVARI either..

I thought anyway..

Paul

You're right, it's not.

The only reason 'our' cars have the FDV, as Shane notes, is the need for them to use a 'conventional' steering rack, as used on Peugeots. Being a conventional system it requires sizable quantities of fluid, at a lower pressure to 'proper' Citroen hydraulics, and the purpose of the FDV is to provide this feed. The DS had a purpose designed bespoke and unique steering system, which is able to make use of unmoderated hydraulic pressure, and so has no need for the FDV which was a clever solution to the imposition of 'conventional' power steering racks.