Is my mechanic on the right track

[Paul02]

Hello
I have a 2000 Xantia 1.8 which sags at the rear after a few hours . Car works fine otherwise rising up and down into high and low etc . No obvious leaks of fluid and no broken plastic linkage etc.

I better point out that I am not great with cars so have to put my trust into a local mechanic . So he changed the rear centre sphere and a valve which sits very close or under it which he calls the anti sink valve ? it's about 3 or 4 inches long has 5 pipe inlets/outlets of which there is 2 each side and one at one end.

This has had no effect on the sinking . He now suggests that we buy what he calls the height control valve which looks like a bellows effect which connects to a spring etc and sits one side of the centre sphere and valve that we have replaced . My question is will this sort out the problem as I can't keep paying out and getting no results.

Thanks Paul

[GiveMeABreak]

One of the other current Xantia owners will be able to help more specifically, but if the rear height corrector was faulty, I would expect the height to remain incorrect when the car was started or in use. Regarding the anti sink valves, there are different types depending on whether your car has Hydractive suspension or not. Post up your VIN so we know exactly the spec you have.

[xantia_v6]

Being a 1.8, it won't have hydrative.

Your mechanic is not being silly, but it would probably be a good idea to eliminate the rear hydraulic rams by disconnecting their leak-back pipes and running those into a jar while the car sits for a few hours, to see if that is where the LHM is going, the same with the return line from the height corrector.

[CitroJim]

The height corrector (what your mechanic describes and the height control valve) is very unlikely to be the culprit as it's isolated from the rear cylinders by the anti-sink valve which again is highly reliable and unlikely to be the prime culprit.

Mike's test of the rear cylinders is an excellent starting point to diagnosis...

Other suspects that need to be eliminated are the rear suspension spheres themselves as ruptured ones can cause this behaviour bit if the rear suspension when running normally is good and soft then they may be OK.

Check too the main accumulator sphere is OK as if it is completely flat there is insufficient hydraulic pressure available a short while after the engine is switched off to permit a rapid and positive closing of the anti-sink valve. The health of the main accumulator can be gauged by listening for the ticks from the pressure regulator that signify it cutting in and out like a thermostat. Those ticks should be separated by at least 30 seconds. Anything less suggests the main accumulator sphere is flat and requires replacement.

[Peter.N.]

My only experience is with XM hydractive's and the sinking problem can be caused by the height corrector valves leaking internally but it hasn't got anti sink of course.

Peter

[Paul02]

Thanks fellas I will pass this info on to the mechanic .
Paul

[harryp]

To cut in to this thread , My year 2000 Xantia rides far too high but is consistent in use at this height. On leaving it overnight it sinks to the correct ride height but no further, even after a week. I am beginning to think there may be an obstruction in the return line close to the HC. Anyone have any experience or comment on this please?? Clue may be that it only did this after a stripdown of both cradle and HC, but I am still baffled as I think that if I reset to correct height, will it then sink further overnight? I cannot reset it on my drive as it's all pebbles and doing it on the road is a definite no no due to the local traffic. May have to find a friendly pub carpark .

[white exec]

It should surely run at the correct height - which, as you say, can be adjusted. If it sinks to something lower when parked up, then either that doesn't matter, or the anti-sink (presumably fitted) isn't working.

[Paul02]

This is regarding the original topic at the top , if this seems too much for the mechanic I am using , as he has already said he is not keen on working on this type of car and suspension , can anyone recommend a garage or individual who could fix this problem aside from main dealers.
I am in SE London / Kent but can travel if need be , thanks Paul

[Peter.N.]

I come from Kent - but live in Dorset now

Peter

[CitroJim]

Paul, you may be fairly near some classic Citroen specialists down your way...

They will both be happy to work on yours and will understand it! Sadly now, few mainstream garages do and those that do are getting hard to find...

[harryp]

Chris, the puzzling thing is that it does not "sink" in the accepted sense, i.e. right down, just to normal ride height ....

[Peter.N.]

Not just a sticky height corrector I suppose?

Peter

[Stinkwheel]

In the old days, if this was happening to say a BX or CX, it would have been a fair bet that the brake dossier had some internal leakage and would need replacing/rebuilding. This nearly always turned out to be the case on these older models, when having rear sink-age issues.

I cannot comment on if this is your problem on the xantia though.

[harryp]

Height corrector and cage was removed, both stripped, cleaned, rebuilt and replaced. Really at a loss. Common sense tells me it must be to do with this, but all seems to work, just too high; but the dropping to normal ride height overnight is the really puzzling bit.....