front suspension going up and down

bikerk100rt · Post by **bikerk100rt** » 27 Apr 2005, 12:49

Hi all, I am new to this forum and have a problem. My Xantia 19td 1994 140k miles has a front end problem. The suspension goes up to normal height then after about 5 seconds drops about 3 inches waits a few seconds then rises to normal height, then starts all over again. When switching off the front drops straight away with a sound like an air leak. the NSF suspension unit is/has leaked at some time. New front spheres fitted but problem still there. The rear is fine no probs. Any help glady accepted.

oilyspanner · Post by **oilyspanner** » 27 Apr 2005, 13:05

Sounds like youe front height corrector is sticky, more than likely the linkages and springs would bebefit from cleaning and lubricating, there are two linkages to the valve itself. one from the anti roll bar and one from the lever inside the car, from your description it sounds like they are "fighting" against one another, get the car up on ramps and under the centre behind the crossmenber you will see it all NEVER WORK UNDER AN UNSUPPORETED CITROEN THEY KILL folks use various cocktails of slippery stuff, grease and chainsaw oil WD etc.
Stewart

Post by **RichardW** » 27 Apr 2005, 13:43

Is it a VSX, and therefore fitted with hydractive suspension?

BX-Basis · Post by **BX-Basis** » 27 Apr 2005, 16:32

Sounds like your front suspension cylinders have internal leakages. Check the amound of LHM coming out of the return lines at the cylinders. There should be no more than a few drops. If there's a great amounf of LHM leaking out, the suspension cylinder(s) must be replaced.

FrenchLeave · Post by **FrenchLeave** » 28 Apr 2005, 05:15

Yep, my XM had an identical fault (in stationary traffic I would watch in the rear view mirror as the rear of my car went up and down against the sight line of the bonnet of the car behind). That was a rear suspension unit leaking internally.

Mandrake · Post by **Mandrake** » 30 Apr 2005, 16:25

When it drops, is it a fairly sudden drop, as if the height corrector is deliberately letting the car down then up again ? Or is it a slow drop followed by a fast rise ?
If you turn the engine off and it drops a couple of inches, does it stay there for some time, or continue to drop right down ?
One thing that can cause the height to hunt up and down continuously is excessive friction in the mechanical components of the suspension - like stiff struts or arm bushes.
This causes the height corrector to over-react. In the upwards direction it takes more pressure than it should because of the friction, and it takes considerable pressure change before the friction is overcome and the suspension actually moves, and when it does it will lurch a couple of inches, and overshoot the mark.
After a few seconds the height corrector will attempt to correct in the opposite direction, and the same thing happens, the pressure has to drop quite a bit before the friction is overcome and the suspension moves, and when it does it will lurch and drop too far.
The same thing can happen if the rollbar has too much preloading. (Clamping tension)
If you try pressing down gently on the suspension does it move smoothly and freely, or does it feel like it has friction that makes very small movements difficult ?
Another thing that can cause unusual corrections in height like this is a flat main accumulator sphere on models with anti-sink valves - every time the suspension demands some oil from the accumulator to lift the suspension the source pressure will suddenly drop below the threshold pressure the anti-sink valve needs, causing the anti-sink valve in the front to momentarily close, then open again when the pressure builds up.
This causes all kinds of amusing lurching in the correction of the front height [:)]
Regards,
Simon

jeremy · Post by **jeremy** » 30 Apr 2005, 17:10

Your 94 Xantia may not have anti-sink as it was introduced during that year.
Is there any chance that air is getting into the pump feed from the reservoir? Air in the system will all manner of strange effects as the valves seal for LHM but not for air as there is no surface tension. The hose from the reservoir is under vacuum and so won't necessarily leak to the outside if its faulty. Anders suggests you substitute a section of clean garden hose for diagnostic purposes.
jeremy

AndersDK · Post by **AndersDK** » 30 Apr 2005, 20:31

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by jeremy

Anders suggests you substitute a section of clean garden hose for diagnostic purposes.
jeremy
<hr height="1" noshade id="quote"></blockquote id="quote">No - the complete hose Jeremy [:)]
AFAIR a new spare parts genuine hose is a rip-off.
But honestly I doubt that air could give such a symptom.
The '94 would have the BX system PAS (1-port pump) with the dreaded FDV. This we know will at some point call out for owners hair pulling.

bikerk100rt · Post by **bikerk100rt** » 04 May 2005, 13:12

Hi All, have sprayed wd40 on rods and connections under car, now a slight improvement but not there yet. The rising after starting is jerky at the front. It falls slowly and smooth and rises again smoothly. It has no anti-sink or hydractive this is a basic model. I am trying hydraflush today if I can get it from local GSF shop. Will post any changes.
Gary [:)]

Mandrake · Post by **Mandrake** » 04 May 2005, 13:28

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by bikerk100rt

Hi All, have sprayed wd40 on rods and connections under car, now a slight improvement but not there yet. The rising after starting is jerky at the front. It falls slowly and smooth and rises again smoothly. It has no anti-sink or hydractive this is a basic model. I am trying hydraflush today if I can get it from local GSF shop. Will post any changes.
Gary [:)]
<hr height="1" noshade id="quote"></blockquote id="quote">
Is the main regulator/accumulator sphere fully gassed ? A flat accumulator sphere can cause symptoms a bit like that...as the pressure pulses from the hydraulic pump are not smoothed out, and the initial lifting is coming directly from the pulsing of the pump without the accumulator there to help.
Try this, run the car and let it pressurize until the height is stable, and you hear the click of the pump switching off. Switch off the engine. Let it sit for about a minute and make sure the height stays the same.
Now sit on the boot, and it should go down a few inches (assuming your back spheres are ok) and after a few seconds it should be able to lift your weight back to normal height again at least once with the engine turned off, by using the stored pressure in the main accumulator sphere.
If it doesn't even budge, your main accumulator is either very low in pressure or dead altogether. If it makes a feeble effort to lift you but doesn't move very far your accumulator has low to moderate pressure, and if it easily lifts you, and even tries to partially or fully lift you a second time (if you get off, let it go down, then sit on the back again) then your accumulator sphere is excellent.
An excellent accumulator sphere can also usually lift you a bit if you do the same test sitting on the front cross-member with the bonnet open, but with a mediocre accumulator it probably won't as higher pressure is needed to lift the front suspension.
Edit: just re-read your post and its still not clear what you're saying. Are you saying that if you let the car come up to the normal height and switch off the engine, that it immediately sinks back down to the bottom again within a few seconds or a minute ??? Please clarify.
Regards,
Simon

davek-uk · Post by **davek-uk** » 04 May 2005, 14:37

I had a similar problem and cured it by greasing the ram of the front suspension struts (up under the plastic cover). Initially, I'd recommend you look for any point the suspension travel can stick. As Mandrake suggests, I think your suspension is sticking and the front height corrector is over correcting.

Mandrake · Post by **Mandrake** » 04 May 2005, 16:56

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by davek-uk

I had a similar problem and cured it by greasing the ram of the front suspension struts (up under the plastic cover). Initially, I'd recommend you look for any point the suspension travel can stick. As Mandrake suggests, I think your suspension is sticking and the front height corrector is over correcting.
<hr height="1" noshade id="quote"></blockquote id="quote">
How easy is this to do ? I think my Dad's Xantia could do with the struts lubricating, its slightly sticky, although not too bad. Did you just pull the plastic gator down from the top, and set the suspension to full height ?
Presumably part of the piston sticks out beyond the cylinder making it possible to get some grease on the bottom end of the piston, then raise and lower the height a few times to work it up into the rest of the pistion/cylinder ?
I've been wondering about this, as I can't find any pictures of what a dissasembled strut looks like on the 'net, and as usual the Haynes manual is useless, and has no pictures or diagrams...
Regards,
Simon

davek-uk · Post by **davek-uk** » 04 May 2005, 18:06

Greasing the front struts has been covered in the past (do a search). Unless I have everything wrong, The conclusion was that the Xantia struts could only be greased externally whilst the earlier BX struts could be internally lubricated with LHM.
With the suspension on full height, the strut ram is accessible under the plastic gator - pull it down from the top. After greasing jump the suspension up and down to spread the grease. It worked for me. Particularly after parking on full lock the front used to go up and down embarrassingly!

Mandrake · Post by **Mandrake** » 05 May 2005, 02:16

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by davek-uk

Greasing the front struts has been covered in the past (do a search). Unless I have everything wrong, The conclusion was that the Xantia struts could only be greased externally whilst the earlier BX struts could be internally lubricated with LHM.
With the suspension on full height, the strut ram is accessible under the plastic gator - pull it down from the top. After greasing jump the suspension up and down to spread the grease. It worked for me. Particularly after parking on full lock the front used to go up and down embarrassingly!
<hr height="1" noshade id="quote"></blockquote id="quote">
Thanks!
Thats just what I wanted to hear...by the way I wonder how many lose their lubrication due to the plastic gators becoming detached ? When Dad bought his 94 Xantia recently (at admitedly a bargain price with a few known repairs that needed doing) both gators had become detached from the top and god knows how long it was like that beforehand letting water and dirt up into the ram area.
The lip that holds it on didn't seem very effective relative to the amount of stretching force thats trying to pull it off again, and I ended up putting a long narrow zip strap on it to make sure it stayed in place, which seemed to work well...
Regards,
Simon

davek-uk · Post by **davek-uk** » 05 May 2005, 14:20

Did the greasing have the desired effect, Simon? My front struts are terrible at sticking. If I do a little citrobics at the start of a journey it makes quite a difference to the ride - but how often do you have the time to play like that? I must get around to cleaning (properly this time) and regreasing the linkages and then checking the state of the strut rams again; it'll be interesting to see how the grease has faired.