My Mk2 Xantia is behaving like a Mk1!

trackrod · Post by **trackrod** » 25 Apr 2005, 03:49

Hi Everyone -'long time since I was last here - I need some advice. My Mk2 Xantia no longer "sit's up" when left parked overnight. Instead the suspenion gradually collapses. I've spent some time going thru the previous forums and it's seems that the Antisink sphere would need replacement. Anyone got any other thoughts?? Regards, Fred

citroennut · Post by **citroennut** » 25 Apr 2005, 13:25

well fred, be pleased it's acting like a proper citroen![:D][:D][:D][:D]
simon

Post by **RichardW** » 25 Apr 2005, 13:35

It's unlikely to be the antisink sphere, since this has not a lot to do with stopping it sinking. Does it sink at both ends, or one only? First thing I would try is hydraflush to see if this makes a difference, also make sure both the height correctors are well lubricated and the height is correctly set.

nexarius · Post by **nexarius** » 25 Apr 2005, 21:48

Hi, its probably your anti-sink valve, which is supposed to stop pressure in the suspension from escaping back into the reservoir when the pump isnt running.
These are notorious for failing on a lot of Citroen cars. (or at least 3 out of 4 that we have had).

trackrod · Post by **trackrod** » 25 Apr 2005, 23:54

Hi again - A giggle for citroennut!! (I suppose that if I stuck the chevrons back on the bonnet I could forget about it!)RichardW- I confess that I was doubtful about the sphere. The sink happened so quickly Yesterday fine -today sunk! Although somewhere in the posts I saw something about the pressure from the sphere holding the antisink valve closed - so am not sure. nexariusThis also makes good sense - valve open, system settles. As a matter of interest (HELP) where can I find this valve? I've been looking thro the Haynes manual but I can't find anything about it. Come to that, I can't find very much info about the suspension at all.
Thank you for your efforts, always appreciated. Fred.

toldem_oldham · Post by **toldem_oldham** » 26 Apr 2005, 00:52

My xantia drops at the back and this weekend i got underneath and my anti sink sphere and related pipes to the sphere are wet through with lhm but no drips and the lhm level is where its supposed to be so ive cleaned off the pipes and relavant areas to see where it is weaping from but up to now it is dry but still drops.

BX-Basis · Post by **BX-Basis** » 26 Apr 2005, 02:19

Be happy that anti-sink doesn't work any more. Your spheres will live much longer without this system !

FrenchLeave · Post by **FrenchLeave** » 26 Apr 2005, 04:37

There has been a posting on A/S valves in the past fortnight, complete with photos. The front anti sink valve is under the reservoir, the rear one is mounted just about centrally on the rear suspension cross tube. I would not be too quick to condemn the A/S valves, sinking can be caused by an internal leak on any component upstream (on the suspension side) from the anti sink valves. In my case it was a leak past the ram in one suspension cylinder. If you check the return pipes at the reservoir you should be able to ascertain which one is carrying a heavier than normal return flow, then by following it back you should find the leaking component. You still havn't answered the question posed by RichardW, which end or both?

trackrod · Post by **trackrod** » 26 Apr 2005, 23:59

Hi FrenchLeave - Ah! now that's something I didn't know Two! antisink valves! Now that poses a problem. I assumed that there was only one valve and logically, if that valve remained open, then the vehicle would sink. Now that I know that there are two valves I am more perplexed and can also understand the question "Does it sink at both ends, or one only?"
The car drops gradually at both ends - nice and level. I'd guess the chances of both valves being defective are a bit remote.
I've inspected the area around and under the vehicle but there is no sign of any leakage and the reservior level is correct.
I've had this car for about a year and have little knowledge of previous service history. I think I'll start off hydraflushing the whole system this weekend. I suppose at worst, there could be a lot of nasty gunge in the circuits which could foul up valves seats and the like. Once I'm happy that the system is clean I'll probe in other directions. Fred

DoubleChevron · Post by **DoubleChevron** » 27 Apr 2005, 07:25

C'mon guys,
there not anti-sink spheres. The back sphere everyone refers to as "anti-sink" is a rear brake accumulator. I think you are now refering to the hydractive spheres as 'anti-sink'. The spheres themselves have nothing to do with the cars sinking. It can ONLY be the anti-sink valves, if they don't prevent the fluid flowing back to the reseviour, the car will drop ...... like a stone ..... Just like any other hydraulic Citroen.
As yours works intermittantly I'd strongly suggest your anti-sink valves are working intermittantly. I doubt the valves have 12volts at them to 'engage' the anti-sink as that means you would be running the battery flat. Rather they would default to anti-sink mode. This should rule out electrical issues (unless it was riding poorly and stuck in 'anti-sink' mode at all times).
Can you dismantle & clean the anti-sink valves ??? There probably just full of black sh!t due to the fluid never being changed.
seeya,
Shane L.

DoubleChevron · Post by **DoubleChevron** » 27 Apr 2005, 07:28

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

Be happy that anti-sink doesn't work any more. Your spheres will live much longer without this system !
<hr height="1" noshade id="quote"></blockquote id="quote">
Why ??? There is still the 1200psi+ of nitrogen against the diaphram regardless of the weight of the car sitting against it. Sphere's go flat sitting on a shelf in your shed just as quick as they will on a car !!
seeya,
Shane L.

BX-Basis · Post by **BX-Basis** » 27 Apr 2005, 16:35

You want to know why ? When the suspension is "up", the nitrogen is compressed by the LHM. The higher the nitrogen pressure, the more nitrogen will pass the membrane in the sphere. That'
s the simple explanation for the phenomenon of "early dying" spheres on older anti-sink Cits.

Panjandrum · Post by **Panjandrum** » 27 Apr 2005, 18:38

That sounds almost believable. But surely the rate of nitrogen loss depends on the difference in pressure across the membrane.
Suspension up = no pressure difference = no loss;
suspension down = maximum pressure difference = maximum loss.
On the other hand I could be completely wrong.

DoubleChevron · Post by **DoubleChevron** » 27 Apr 2005, 18:49

My Xantia is a '94 build. The front sphere's are still fully gassed and original, the rears were down to 50% as were the accumulators, the rear brake H/A sphere was dead. 1 new sphere only required in an 11year old car (with anti-sink). I don't call that 'early dying'.
seeya,
Shane L.

fastandfurryous · Post by **fastandfurryous** » 27 Apr 2005, 18:55

This depends a lot on how easily Nitrogen dissolves into LHM. I don't know the answer to that. If Nitrogen dissolves relatively easily into LHM (which I suspect it may do) then it won't make much difference if the suspension is up or not.