That sinking feeling... Xantia VSX

[JohnW]

Hi,

Not sure why there would be pressure on one side and not the other, but just a tip when depressurizing an anti-sink model - you need to set the height lever to minimum with the engine idling and WAIT at least 2 minutes (maybe even 3) before you open the bleed screw or turn the engine off.

Regards,
Simon

Many thanks to all for this one - very instructive thread.

Cheers

JohnW

[steelcityuk]

Excellent thread, loads of good info. I think I might try disconnecting the rear HA valve to see if this is functioning as it should. I'm still not convinced that the suspension on mine is working as it should. It never feels floaty and not really any better than my old 405 did. Come the weekend I may replace the rear strut spheres, these are the only one I haven't replaced since buying the Xantia.

Also can anyone describe the noise that the pressure regulator makes on their Xantia, is it like a BX or different? I seem to remember BXs making a hissing followed by a click, my Xantia doesn't sound anything like that, is this because of the different pump & regulator setup?

Thanks.

[Mandrake]

Bear in mind if you unplug the rear electrovalve the computer will also disable the front one, putting both ends of the car into hard mode.

Also its the centre hydractive spheres that give the floaty smooth ride, not the strut spheres. If the strut spheres are good but the centre ones are not, you won't get a soft ride...

Regards,
Simon

[steelcityuk]

Thanks for the heads up. All the other spheres were changed in the summer so they 'should' be OK.

[mrjohnson]

Steelcityuk

Bought a '99 Hdi 110bhp recently.

The pump sounds completely different from my old 1.9 TD Xantia.

For a while after I bought the car I was convinced there was a 1970s "trimphone" trapped under the bonnet! Those were the ones which 'warbled' rather than rang. Very odd noise.

Regards

Martyn

[steelcityuk]

Mr J,

That sounds similar to mine, a sort of warble followed by a click. However mine does it every 15-20 seconds even though I've changed the accumulator sphere. How long does go between warbles?

BTW I have an old trimphone in the bedroom, I love the ringing sound so I've also put it on my mobile.

Thanks for the info.

Steve.

[jeremy]

I thought all the trimphones had been destroyed as they were radioactive!

If the regulator is still cycling every 20 seconds with a new accumulator it may be that the non-return valve in the regulator needs re-seating. This is done by a smart tap with a brass punch. There are full instructions in many places on here.

[RichardW]

The regulator kicking in every 20s is because the hydractive valve is dumping the pressure.... Whilst it might not be directly related to the rear sinking, it will certainly not be helping!

[steelcityuk]

Hi Jeremy,

Yes they did destroy the radioactive trimphones, unfortunately mine's a push button type so isn't a glow in the dark type. I think it was just a precautionary measure as the radiation doseage from one would be tiny according to 'experts' because it used a tritium gas capsule.

http://web.ukonline.co.uk/freshwater/t712.htm

Richard,

could you give me some idea of why the hydractive valve would be dumping the pressure? Is it a faulty valve? If so are they reconditionable?

Sorry for all the questions!

Thanks.

[mrjohnson]

Steve,

Havn't measured the cycling rate, but if I was guessing I would say a 2 second run every 60 to 90 seconds.

Next time I'm out in the car I'll try and time it.

Regards

Martyn

[ekaftan]

The regulator kicking in every 20s is because the hydractive valve is dumping the pressure.... Whilst it might not be directly related to the rear sinking, it will certainly not be helping!

Can you please point to a flow diagram to explain this? I have read several and there is no way from pressure to escape via the Hydractive valve, except via the height corrector.

[Mandrake]

The regulator kicking in every 20s is because the hydractive valve is dumping the pressure.... Whilst it might not be directly related to the rear sinking, it will certainly not be helping!

Can you please point to a flow diagram to explain this? I have read several and there is no way from pressure to escape via the Hydractive valve, except via the height corrector.

Richard is right - the input to the electrovalve comes straight from the high pressure supply at the main regulator/accumulator, not via the height corrector. Although it shouldn't (in theory) cause the car to go down on an anti-sink model, it WILL quickly deplete the pressure available at the main accumulator after the engine is turned off, and this can cause all kinds of weird effects.

I do have diagrams that show this but unfortunately I don't have a scanner, so you'll have to take my word for it

This pressure is used to displace the slide valve in the main hydractive control block to enable the "soft mode".

The small pipe that goes into the hydractive control block in line with the electrovalve is full system pressure from the main regulator. The small pipe next to it comes from the height corrector.

The electrovalve is basically a double ended needle valve with a spring that holds it sealing one end when not powered (the high pressure input) and sealing the other end when powered (the overflow return) and by doing so it applies full system pressure (170 bars) or 0 pressure to one end of the slide valve thus moving it. (The other end has suspension pressure on it which is somewhere inbetween)

Normally there is no direct flow between this high pressure input on the electrovalve and the overflow except for a brief moment as the valve changes from one state to the other.

What goes wrong is that the tapered seat or pin of the needle valve on one end wears enough that it wont seat properly, and leaks all the time. Depending on which end is leaking it will affect whether it leaks in the on mode or the off mode.

On my car at the front the overflow one was the one that was leaking, so mine would leak in the "on" (soft) mode, but not in the off mode.

The leakage was enough to cause the regulator to cycle every 12 seconds or so with a good accumulator sphere. (With the engine turned off you could actually hear the leakage hissing!)

I disassembled the valve to try and find the problem and the only visible sign of trouble was a very microscopic bruise on the taper of the pin - but with 170 bars of pressure thats enough!!

I ended up replacing the electrovalve and it stopped the leak and fixed the regulator cycle time.

At no time have I have problems with the car not staying up though, it has always stayed up very well, with no loss of height after 8 hours, and only a small loss of height overnight...

Regards,
Simon

[ekaftan]

Richard is right - the input to the electrovalve comes straight from the high pressure supply at the main regulator/accumulator, not via the height corrector. Although it shouldn't (in theory) cause the car to go down on an anti-sink model, it WILL quickly deplete the pressure available at the main accumulator after the engine is turned off, and this can cause all kinds of weird effects.

I do have diagrams that show this but unfortunately I don't have a scanner, so you'll have to take my word for it

Wow. Thanks! And yes, I do take your word. I know which pipes you are refering to.

My green Xantia cycles rarely. 30 secs to a minute, so that's not leaking. It fails the 'shut down the engine and sit on the trunk' test, so the accumulator or the antisink sphere might be low.

My beige Xantia has a broken HA2 ECU so its stuck in hard mode (ecu on its way, thanks phil . That one cycles every 15 seconds but passes the 'sit on trunk' test perfectly so that one must have a leak on the sphere or one of the electrovalves, right?

[citroenxm]

They all do it sooner or later.... my 97 VSX does too - and has done since I got it (2 years / 40k ago!).

Where do you get that from ? Sinking in 15 seconds is a pretty unusual problem, (I've only seen it mentioned on this forum a couple of times) not a comon one, nor an inevitable one...

The most likely cause is internal leakage in one or other of the hydractive electrovalves (probably the front, they seem worst afflicted!). You will probably hear a click followed by a hiss a few seconds after you switch off. You may well find that if you unlpug one of the valves, the symptoms will go away - of course you can't really drive it like that as it will be hard as nails! Unfortunately the only real solution is replacement of the electrovalve - and they cost > a ton from the dealer. You could replace it with a known good 2nd hand one - the front and rear are interchangeable, and the rears as I said seem much less afflicted.

I don't think theres any way that a leaking electrovalve can cause this problem on an anti-sink model - yes it could happen when a specific seal failed in the electrovalve on the early non anti-sink models, but the specific path of leakage this caused is prevented by the anti-sink system.

Going down that fast theres really only a couple of possibilities - the brake doseur valve is leaking like crazy, or one of the rear suspension cylinders is leaking like crazy. (And a slight chance its the height corrector)

Here's how it should be possible to isolate which one it is - first I'd try setting the height control lever to the high position just as the engine is switched off, and if the back still goes down its probably not the height corrector.

Next thing I'd try (engine back on again and height lever at normal) is once the height is stable, open the main pressure regulator bleed screw half a turn then turn off the engine.

This will cause the anti-sink valves to immediately close. If the back now stays up you know that the leakage is not the cylinders, and is almost certainly the brake doseur valve. (The anti-sink valve has now isolated the doseur valve from the suspension)

If it still goes down just as fast when the bleed screw is open, either one of the rear suspension cylinders is leaking like crazy through one of the return pipes, or the anti-sink valve itself isn't working, in addition to the main problem.

Thats my take on things anyway!

Regards,
Simon

Hi Simon,

Tried your test today, car in Normal Height position. Engine running, opened the regulator, and she sank to the bottom! Just like turning the engine off....

Does this point to the Anti sink valve then?? I'm sure I have a spare from an SX Anti sink car that did work..

Await your reply.

Regards
citroenxm

[Mandrake]

Hi Simon,

Tried your test today, car in Normal Height position. Engine running, opened the regulator, and she sank to the bottom! Just like turning the engine off....

Interesting! So it started dropping as soon as you opened the bleed screw ? How quickly ?

Does this point to the Anti sink valve then??

Well one more thing I should have thought to ask - if you leave the engine idling and the bleed screw closed as per normal and watch the rear suspension closely, does it stay perfectly still at the normal height ? Or does it slowly fall a cm or two then lift, then fall, then lift etc ?

If there was high leakage in the cylinders it should cause the height to try and sink all the time - but with the engine running it will only fall a small amount before the height corrector wakes up and lifts it up again - thus a small continual oscillation in the height while stationary.

If the height is perfectly steady for extended periods of time with the engine running and then it drops like a rock when you open the bleed screw then I would say yes, its highly likely the anti-sink valve is faulty.

I'm sure I have a spare from an SX Anti sink car that did work..

Your car is Hydractive 2 right ? Unfortunately an SX is not, and the anti-sink valves in a HA2 and a non-HA2 car are NOT the same.

So you'd have to get one from a Hydractive 2 model.

Regards,
Simon