Xantia sinking when engine stops.

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Xaccers
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Xantia sinking when engine stops.

Post by Xaccers »

My 2.1TD has a problem where as soon as I turn the engine off, it starts to sink.
Now I've replaced the acc sphere twice, first from GSF with one that did look a tad old, then with one from Jim which he knew was a goodun.
The boot test has always failed.

Other than a flat acc sphere, is there anything else which can cause a Xantia not to stay up when the engine is stopped?
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Post by AndersDK »

Its known that the antisink valves may fail for any reason.
Has your 2.1td seen a hydracleanse cure ?
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Post by CitroJim »

I suppose the obvious first suspect has to be the anti-sink valve itself and being as your 2.1 is not Hydractive Andy, on the face of it there is not a lot else that immediately springs to mind.

You've got new front spheres havn't you?

Except...

Think how the anti-sink works. It isolates the front strut hydraulic fluid supply as soon as there is a distinct pressure differential between the pressure in the struts and the supply pressure from the height corrector.

So, it could be a problem with your front height corrector. I'm wondering if your plastic link is intact on the front height corrector. The front height correction is nowhere near as "active" as the rear as the ratio of change of weight at the front is nowhere near that at the back and therefore the front one does not move that much in reality and it is possible not to realise there is a problem as you would if the rear plastic link was adrift.

A good test is to do citarobics and go from low to normal. Does the car rise up normally? Do the same test from high to normal. Does the front fall back to normal of its own accord or is it necessary to go from high right down to low and then to normal to get it back to normal height?

Can you provoke a front height correction by sitting on the front of the car?

If this is all Ok and the regulator tick rate is long then the height corrector would seem OK. Even if the accumulator was completely flat, the anti-sink should still work as designed.

Other than the anti-sink valve, massive leakage in your front struts could be the problem. How much leakage do you see in the strut leakage returns when you stop? It is very easy to check by pulling off the rubber hoses under the wings. Anything more than a dribble will be worrying and only one strut needs to be leaking badly to affect both sides as they remain interconnected through the anti-sink valve.
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Post by CitroJim »

Another thought on tha supplementary question concerning the "sit in the boot" test.

That has to be caused by a leak somehere in the system bleeding off pressure very quickly when you stop which inter-relates back to your first problem.

When you stop the engine, it should take a finite time before the regulator "hits in" with a loud tick as pressure falls in the system. My Activa can go quite a long time from being switched off and giving its final regulator tick. This obviously depends on how long it was since it last ticked but if the tick occurs immediately on switch-off them I'd be suspecting an internal leak somewhere.

If we go back to your first problem and assume it is caused by a leaky front strut then the front anti-sink valve will not close (no pressure differential) and system-wide pressure will be lost very quickly.

What is your normal idling tick rate now Andy?
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Post by Xaccers »

Hydrorincage/new LHM was done about 6000 miles ago, and filters cleaned.
All sphere's have been replaced when I got it just before the hyroflush.
Acc sphere replaced twice now.

Ticks over about 800rpm, nice and smooth.

If I set him on high and turn the engine off, he'll stay up.

Low-high, and high-low is fine and I do citrobics regularly.
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Post by CitroJim »

Xac wrote:Ticks over about 800rpm, nice and smooth.
No, I meant the regulator tick rate :wink:
If I set him on high and turn the engine off, he'll stay up.
:?

Does the whole car sink down Andy? I was thinking it was only the front that sank from what I recalled.
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Post by Xaccers »

citrojim wrote: No, I meant the regulator tick rate :wink:
Oops, it's been a long day, new job working 12 hour shifts!
Incidently, were you heading down V7 yesterday at about 7pm?
citrojim wrote: Does the whole car sink down Andy? I was thinking it was only the front that sank from what I recalled.
Front and back.
I pop to tesco, come back out 30 mins later and when I start him up I have to wait for him to rise.
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Post by CitroJim »

Xac wrote:Front and back.
I pop to tesco, come back out 30 mins later and when I start him up I have to wait for him to rise.
:?

This looks increasingly like an internal leak somewhere bleeding pressure in such a way as to prevent the anti-sink valves coming into operation. I can't believe both anti-sink valves have failed.

Brake doseur perhaps? That might account for the fact it stays up if set on high.
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Post by Xaccers »

Brake doseur, doesn't that normally mean lhm leak into the foot well?
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Post by jeremy »

The doeseur can suffer from internal leakages which simply return to the reservoir through the return pipework system.

I thought the purpose of the rear anti-sink valve was to isolate the suspension from the doseur and height correctors which always leak slightly. The doseur isn't in the front suspension circuit.

Is there any possibility of a leak in the pipe between the reservoir and the pump - which lets in air - which would separate and the valves could act as sieves - separating the air from the LHM and allowing the car to drop? The ends must be sound and tight. As its under suction it lets air in and not LHM out.
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Post by AndersDK »

As I understand by your question Jim, Xac's Xantia had the rear sink from beginning. Now it also shows front sinking.

That could still be a likely scenario, as both a/s valves have not failed exactly at the same time then.

Another possibility is that Xac's Xantia does NOT have the a/s system fitted after all :idea:
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Post by Xaccers »

Well, it has an a/s sphere, it's a 1998 2.1TD estate, and since I've had it, it's sunk when the engine was turned off.

Regulator tick is very long, actually I rarely hear it.
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Post by Xaccers »

Updates:

It sinks when the engine is turned off and you then get out, just turning the engine off the car stays up.

Going from low to high, the back goes up first, the front then slowly follows.
Going from high to low, the front dives down, then the back slowly follows.

Boot test produces a really weak attempt to rise, maybe 2-3cm, certainly not up to level.

Suspension when driving feels quite hard, but not empty sphere hard (and the spheres apart from the acc were put on only a few months ago, they're stamped 2006) pushing the bonnet down gives movement but it feels stiff.
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Post by CitroJim »

Xac wrote:Updates:

It sinks when the engine is turned off and you then get out, just turning the engine off the car stays up.

Going from low to high, the back goes up first, the front then slowly follows.
Going from high to low, the front dives down, then the back slowly follows.

Boot test produces a really weak attempt to rise, maybe 2-3cm, certainly not up to level.

Suspension when driving feels quite hard, but not empty sphere hard (and the spheres apart from the acc were put on only a few months ago, they're stamped 2006) pushing the bonnet down gives movement but it feels stiff.
Andy,

Sounds normal to me now. It's correcting for the change of weight as you get out. I'll wager that if you watch carefully, it rises at the front as soon as you get out and then drops back to the correct level under the influence of the height corrector as it should. The giveaway is that it stays up whilst you stay in the car. You're a big bloke and there will be a change of height as you get out. A 10 stone featherweight like me does not cause a height change. Try it with Shani in and out of the drivers seat instead of you :wink:

Are you 100% sure you have the right front spheres? You've not accidentially got Hydractive ones have you? They'll make the front feel hard but as you say, not "empty hard"
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Post by Xaccers »

Will check their codes tomorrow, when I fitted the acc you gave me, the suspension felt softer for a while.
Just finished 4 night shifts and been up all day to reset my body clock so in definite need of some beauty sleep (Shani's moaning that Mr Grumpy is here instead of me)
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