As long as the hydraulic system is pressurised - ANY sphere have exactly equal pressure on both sides of the membrane.
Meaning the antisink system at least prolongs the life of the wheel spheres.
The Nitrogen gas is not "dissolved" into the LHM if/when a sphere leaks. The N-gas is simply there as any air - i.e. compressed by the existing system pressure and making for the wellknown "feature" of the odd bumpy ride.
It is vented out when you do the Citaerobics.
My Mk2 Xantia is behaving like a Mk1!
Moderator: RichardW
The duration of the spheres depends on the usage of the car. I have experienced, that the spheres die very fast on anti-sink Xantias that don't move most of the time. I just replaced all spheres on a '99 X2 with only 37.000 kms. The front spheres were almost dead, the rear spheres had no more nitrogen. Other Xantias drive over 150.000 kms with one set of spheres. It's kind of strange...
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by BX-Basis</i>
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.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by BX-Basis</i>
The duration of the spheres depends on the usage of the car. I have experienced, that the spheres die very fast on anti-sink Xantias that don't move most of the time. I just replaced all spheres on a '99 X2 with only 37.000 kms. The front spheres were almost dead, the rear spheres had no more nitrogen. Other Xantias drive over 150.000 kms with one set of spheres. It's kind of strange...
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Choose either ?
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.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by BX-Basis</i>
The duration of the spheres depends on the usage of the car. I have experienced, that the spheres die very fast on anti-sink Xantias that don't move most of the time. I just replaced all spheres on a '99 X2 with only 37.000 kms. The front spheres were almost dead, the rear spheres had no more nitrogen. Other Xantias drive over 150.000 kms with one set of spheres. It's kind of strange...
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Choose either ?
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FrenchLeave
- Posts: 359
- Joined: 18 Jan 2005, 21:47
- Location: 5 miles N. of Boston, Lincs
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Originally posted by DoubleChevron
" 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."
Hi Shane,
Richard W already discounted the anti sink sphere and gave a full description of its true function. As far as the anti sink valves are concerned, they don't have an electrical supply to engage them - they are purely hydromechanical in operation. You appear to be confusing the hydractive control valve (which does have an electrical supply to engage it) with the anti sink valve. As far as your statement that only the anti sink valves can be responsible for the car sinking, I'm afraid that that's a load of old cobblers. All the components on the suspension side of the A/S valves have leakage return pipes and an excessive internal leak from any one of them will cause the suspension to drop. As. of course, will a leak past the A/S valves themselves.
Hi Fred,
Your new information is a bit perplexing. I can't think of any component that is shared between front and rear suspensions to cause both ends to sink like that, I was hoping that Anders would come in on this one as he is an acknowledged expert. In the meantime, I can only suggest that, if hydraflushing doesn't do the trick, you check the return lines at the reservoir for leakage flow.
Good luck, Derek.
" 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."
Hi Shane,
Richard W already discounted the anti sink sphere and gave a full description of its true function. As far as the anti sink valves are concerned, they don't have an electrical supply to engage them - they are purely hydromechanical in operation. You appear to be confusing the hydractive control valve (which does have an electrical supply to engage it) with the anti sink valve. As far as your statement that only the anti sink valves can be responsible for the car sinking, I'm afraid that that's a load of old cobblers. All the components on the suspension side of the A/S valves have leakage return pipes and an excessive internal leak from any one of them will cause the suspension to drop. As. of course, will a leak past the A/S valves themselves.
Hi Fred,
Your new information is a bit perplexing. I can't think of any component that is shared between front and rear suspensions to cause both ends to sink like that, I was hoping that Anders would come in on this one as he is an acknowledged expert. In the meantime, I can only suggest that, if hydraflushing doesn't do the trick, you check the return lines at the reservoir for leakage flow.
Good luck, Derek.
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DoubleChevron
- Posts: 622
- Joined: 22 Sep 2003, 18:06
- Location: Australia
- My Cars:
- Contact:
I actually haven't studied the anti-sink circuit at all. Yes it will sink slightly if left for long periods of time (the anti-sink valves must leak to some extent).
However my point stands, sphere's should in no way affect the time it takes for the car to drop. Anti-sink has to work by preventing the fluid stored in the suspension circuit returning to the reseviour. No amount of 'storage' of pressure ie: accumulators/spheres is going to prevent the car sinking, only temporarily prevent sinking until the spheres are exhausted of pressure reserves (were talking hours/minutes here depending on the leakage rate of the suspension circuit).
Does anyone have an exploded diagram of an anti-sink valve so we can see how it works ?? This *has* to be the reason the suspension is settling.
I imagine the only reason they fitted anti-sink valves is the Xantia with 6&2hydraulic pumps takes aaaaaaaaagggggggggggggeeeeeeeeeeeeesssssssssss to lift from flat with only 2piddly little pistons pressurising the cars hydraulics.
seeya,
Shane L.
However my point stands, sphere's should in no way affect the time it takes for the car to drop. Anti-sink has to work by preventing the fluid stored in the suspension circuit returning to the reseviour. No amount of 'storage' of pressure ie: accumulators/spheres is going to prevent the car sinking, only temporarily prevent sinking until the spheres are exhausted of pressure reserves (were talking hours/minutes here depending on the leakage rate of the suspension circuit).
Does anyone have an exploded diagram of an anti-sink valve so we can see how it works ?? This *has* to be the reason the suspension is settling.
I imagine the only reason they fitted anti-sink valves is the Xantia with 6&2hydraulic pumps takes aaaaaaaaagggggggggggggeeeeeeeeeeeeesssssssssss to lift from flat with only 2piddly little pistons pressurising the cars hydraulics.
seeya,
Shane L.
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FrenchLeave
- Posts: 359
- Joined: 18 Jan 2005, 21:47
- Location: 5 miles N. of Boston, Lincs
- My Cars:
Hi Fred -
To summarise all postings up to now :
1) The rear a/s sphere is in fact more a rear brakes accumulator.
2) as the car drops both front & rear you have a common problem to both front and rear a/s valves.
3) the a/s valves works by pressure difference. No electric controls.
I'm still a bit confused as if your Xantia has either hydractive or antisink - or both - fitted.
You only say Xantia MkII ? Whats the model designation ?
Have you actually spotted with own eyes the spheres involved (and proving) the various systems fitted ?
To summarise all postings up to now :
1) The rear a/s sphere is in fact more a rear brakes accumulator.
2) as the car drops both front & rear you have a common problem to both front and rear a/s valves.
3) the a/s valves works by pressure difference. No electric controls.
I'm still a bit confused as if your Xantia has either hydractive or antisink - or both - fitted.
You only say Xantia MkII ? Whats the model designation ?
Have you actually spotted with own eyes the spheres involved (and proving) the various systems fitted ?