Replaced my flat accumulator sphere, still getting a bumpy ride

[kenbw2]

My pump was clicking once every 5 seconds, and when I took the accumulator sphere off it was definitely flat - when I put a screwdriver in to feel where the diaphragm was, I was able to put it pretty much all the way in.

I've put a replacement on - an anti sink sphere actually - and it's improved somewhat but still not doing very well.

I've done a few tests going over speed bumps at 30kph. Most of the time it's fine, but maybe 1 in 6 times it feels very hard, like it's hitting the bump stops.

One of the speed humps, it felt like it landed then immediately lost pressure but I could be misunderstanding.

I've done the bounce test on all 4 corners and they all seem to bounce back nicely. And the pump is clicking way less frequently.

Any thoughts what could be happening?

[white exec]

Can't remember whether you are Hydractive or not, Ken.
If HA, centre spheres also need checking out.

Did you bleed the hydraulic system after replacing spheres? Air in the system can cause random crashiness, as air trapped near the spheres can be suddenly compressed (unlike continuous fluid) when going over humps. Doing a good few Citrobics can help shift air, but no substitute for a proper bleed.

[kenbw2]

Mine's Hydractive yes. I got about 1.5 litres of fluid in if that changes anything.

I gathered it's self bleeding, and I did ask about that, so not bled anything. I'll try a few Citrobics, see if helps some.

[xantia_v6]

I had not realised that your car has hydractive, that raises a number of possible issues.

The first and most important is that a flat corner sphere is often not noticed because the centre spheres do the work 90% of the time.
If you do a bounce test with the hydractive valves closed (engine off, all doors closed for a minute), you will find that the suspension is quite stiff, but there should still be a bit of movement if you lean on each corner. At the front it can seem very stiff, but if you watch the front tyre when leaning on the corner, there should be more movement in the suspension than flexing in the tyre sidewall, if the tyre seems to have more give than the suspension, then you have a flat corner sphere, which puts a lot of strain on the strut tops (which are a bit of a weak link anyway).

If you are confident that your corner spheres are OK, the next most common problem is air in the system, often sucked in through perished ends of the pump suction hose. In this case, you will find that the car rides better after a round of citerobics, but after driving for a while, the suspension gets crashy again.

The other endemic problem is the original hydractive valves which have a design that relies on the system (accumulator) pressure being higher than the peak pressure in the suspension. When the pressure regulation spring in the regulator gets a bit tired, the system pressure gets lower, to the point where the hydractive valves close momentarily when going over a bump, which is just whne you don't want it... (see viewtopic.php?p=494381#p494381 for more details)...

There is a related (and common) problem where the hydractive electrovalves become internally leaky, reducing the line pressure at the valve and sometimes making the valves fail to open at all (see viewtopic.php?p=232202#p232202).

This is before we get to electrovalve diode failure...

[GiveMeABreak]

Perhaps the VIN would of helped earlier on - and may still do with further issues.

[white exec]

To do a decent system bleed you'll need a bit more than 1.5 litres, which is cutting it a bit fine.
An extra litre should do.
The proper bleeding procedure has been written up here before.
An 8mm single-hex flare-nut spanner is a good idea, to prevent rounding off the bleed screws.

[Hell Razor5543]

I would also suggest using Plus Gas on all the brake bleed nipples first (a daily application for about a week) so you should then be able to undo them with a greatly reduced chance of them snapping.

[kenbw2]

Perhaps the VIN would of helped earlier on - and may still do with further issues.

Yea you're right, I'll add it now. Better late than never I suppose

VF7**************[VIN obfuscated, can be read by forum staff]

[kenbw2]

I had not realised that your car has hydractive, that raises a number of possible issues.

Oh man, affirming my belief that simpler is better!

The first and most important is that a flat corner sphere is often not noticed because the centre spheres do the work 90% of the time.
If you do a bounce test with the hydractive valves closed (engine off, all doors closed for a minute), you will find that the suspension is quite stiff, but there should still be a bit of movement if you lean on each corner. At the front it can seem very stiff, but if you watch the front tyre when leaning on the corner, there should be more movement in the suspension than flexing in the tyre sidewall, if the tyre seems to have more give than the suspension, then you have a flat corner sphere, which puts a lot of strain on the strut tops (which are a bit of a weak link anyway).

I just gave that a go. Car's been off all night and doors closed. There's definitely much more give in the front suspension than the rear. The rear does what you describe where the tyre sidewall has more give than the suspension. So I guess that's it.

If you are confident that your corner spheres are OK, the next most common problem is air in the system, often sucked in through perished ends of the pump suction hose...

The other endemic problem is the original hydractive valves...

There is a related (and common) problem where the hydractive electrovalves become internally leaky...

This is before we get to electrovalve diode failure...

I knew this car would be a liability But I just culdn't say no to a Xantia!

[white exec]

It's complex, but all straightforward and well understood, Ken.
Decently sorted, the ride on a Hydractive Xantia is extraordinarily good. Don't lose heart!

Just out of interest, do you have access to anyone who can re-gas spheres? Re-gassing is an option (for classic round green or grey ones) and can save money if you intend keeping the car. DIY re-gas kit is about £150, gas cost negligible, and straightforward if you can remove and refit spheres yourself.

If the car's sphere history is unknown, there are two options: replace the spheres (4 corner + 2 centre), or invest in the re-gas kit, which will enable the existing ones to be tested, and potentially re-used. NB: Saucer-shape spheres (if you have any) are not regassable, but can normally be replaced by classic ones.

[kenbw2]

As it happens I've just been to see the local Club owner to attempt to get my accumulator regassed. Unfortunately fluid came out of the other end so the sphere was dead, but I got a replacement so all good.

Driving round today after having done some Citrobics has definitely improved things a lot. It did get bumpy again after I braked hard. The aforementioned club owner suggested this could be that braking hard used up a lot of the pressure, which was depleted more quickly because I have the anti sink sphere on the front.

He also checked out my corner spheres and said they're a little on the firm side but all fine. When I checked them I didn't have the engine running, which was probably not the right way to do it

[white exec]

Hi Ken,

Braking hard is one of the things (on Hydractive) that is meant to immediately switch the system to Firm, so maybe nothing amiss there.

The other things that also instantly put the system into Firm are:
- rapid or dramatic movement of the steering wheel
- rapid or dramatic movement of the accelerator pedal
- a significant amount of body movement (in any direction, dive, squat or roll)
....i.e. anything that requires the car to be taut and stable, anticipating a rapid manoeuvre.

The switch to Firm is within milliseconds, and the reversion to Soft within a 2-3 seconds.

When in Firm mode, the car is riding only on the four corner (wheel) spheres, which provide limited springing, and quite heavily damped. If a road bump or ridge is taken while in Firm (eg braking hard while encountering a pothole, or driving fast over a speed bump) a thud/crash can be expected, particularly from the rear end. This is because the front end senses the road defect, and the system switches into Firm just in time for the rear end to have to deal with the same bump!

Soft ride is provided by the centre spheres being switched into circuit. They provide extra gas capacity (springing) in addition to the corner spheres, and are softer (less damped) than the corner ones. The valves to which they attached (the front and rear Suspension Regulators) are hydraulic, but electrically controlled by a solenoid (electrovalve) built into them, and switched on (Soft) and off (Firm) by the suspension ECU.

In normal driving (IGN on, engine running, non-dramatic driving) the EVs are energised (you might hear them buzzing for 30secs or so when you switch the IGN on, or park up), and the car is in Soft - all six spheres in circuit. This is why you cannot do a bounce test to assess the corner spheres alone with the engine running. It must be off, and all doors etc closed for more than the 30secs.

Forgive me if you knew all this already, but it does help understand what to expect. There's a really good description, well illustrated, of Citroen's systems, including Hydractive, here...
http://citroen.tramontana.co.hu/en/the- ... ical-guide
Well worth a leisurely read!
__________

Good news that you have access to re-gassing. After the re-gassing (Valprex) valves are fitted, it's good practice to check sphere pressures (and top up gas as needed) with the spheres removed from the car. This avoids potential mis-reading of sphere gas pressure, due to any remaining hydraulic pressure still in the system. And, as you found out, it shows up a perforated/punctured sphere, where fluid (and gas) squirt out of the damper as fresh gas is put in. Re-gassing can save a fortune in spheres, and it's worth checking sphere pressures every 2-3 years. If you don't let them go flat (or below 10 or so bar), they can last a really long time.

[kenbw2]

Hi Ken,

Braking hard is one of the things (on Hydractive) that is meant to immediately switch the system to Firm, so maybe nothing amiss there.

The other things that also instantly put the system into Firm are:
- rapid or dramatic movement of the steering wheel
- rapid or dramatic movement of the accelerator pedal
- a significant amount of body movement (dive, squat or roll)
....i.e. anything that requires the car to be taut and stable, anticipating a rapid manoeuvre.

The switch to Firm is within milliseconds, and the reversion to Soft within a few seconds.

Ah, this demystifies some of the things I've heard about firm mode, thanks. It did stay bumpy for a minute or so after and definitely didn't feel like normal operation.

When in Firm mode, the car is riding only on the four corner (wheel) spheres, which provide limited springing, and quite heavily damped. If a road bump or ridge is taken while in Firm (eg braking hard while encountering a pothole, or driving fast over a speed bump) a thud/crash can be expected, particularly from the rear end. This is because the front end senses the road defect, and the system switches into Firm just in time for the rear end to have to deal with the same bump!

Soft ride is provided by the centre spheres being switched into circuit. They provide extra gas capacity (springing) in addition to the corner spheres, and are softer (less damped) than the corner ones. The valves to which they attached (front and rear Suspension Regulators) are hydraulic, but electrically controlled by a solenoid (electrovalve) built into them, and switched on (Soft) and off (Firm) by the suspension ECU.

You've explained this amazingly clearly. I've often tried to understand what all 8(!) spheres are doing - this makes much more sense than any of the diagrams I've tried to follow!

In normal driving (IGN on, engine running, non-dramatic driving) the EVs are energised (you might hear them buzzing for 30secs or so when you switch the IGN on, or park up), and the car is in Soft - all six spheres in circuit. This is why you cannot do a bounce test to assess the corner spheres alone with the engine running. It must be off, and all doors etc closed for more than the 30secs.

Actually I've done both now - one with the car having been parked all night, and one with the engine running. After the overnight, the rear was basically solid. I'm told this indicates the anti sink sphere isn't great.

The test the Citroen club owner did was with the engine running, but like you say it doesn't necessarily check things very precisely.

Forgive me if you knew all this already, but it does help understand what to expect. There's a really good description, well illustrated, of Citroen's systems, including Hydractive, here...
http://citroen.tramontana.co.hu/en/the- ... ical-guide
Well worth a leisurely read!

Some good bedtime reading!

Good news that you have access to re-gassing. After the re-gassing (Valprex) valves are fitted, it's good practice to check sphere pressures (and top up gas as needed) with the spheres removed from the car. This avoids potential mis-reading of sphere gas pressure, due to any remaining hydraulic pressure still in the system. And, as you found out, it shows up a perforated/punctured sphere, where fluid (and gas) squirt out of the damper as fresh gas is put in. Re-gassing can save a fortune in spheres, and it's worth checking sphere pressures every 2-3 years. If you don't let them go flat (or below 10 or so bar), they can last a really long time.

This is valuable yes. I didn't want to start taking spheres off just yet as I need to rely on the car for a club meet tomorrow! But it does sound well worth it.

Actually I need to bleed the system as it became apparent when we took the sphere that the fluid in there is red. not green! I think the last owner has been using LDS!

[xantia_v6]

In normal driving (IGN on, engine running, non-dramatic driving) the EVs are energised (you might hear them buzzing for 30secs or so when you switch the IGN on, or park up), and the car is in Soft - all six spheres in circuit. This is why you cannot do a bounce test to assess the corner spheres alone with the engine running. It must be off, and all doors etc closed for more than the 30secs.

Actually I've done both now - one with the car having been parked all night, and one with the engine running. After the overnight, the rear was basically solid. I'm told this indicates the anti sink sphere isn't great.

BZZZT Wrong information.

The anti-sink sphere has no effect on the suspension whatsoever, it is not really connected to the suspension. It acts as a safety reservior to ensure that the rear brakes are still operational even if there is a sudden loss of pressure in the main hydraulic circuit which will render the front brakes inoperative.

[white exec]

If LDS fluid has been in there it probably won't have done any real damage, as it is also a mineral hydraulic oil. Not recommended, though.

Rather than b*gg*r about, get hold of a 5L container of Total Hydraurincage. Available from Citroen parts counters (they may have to order it in), and a few other places. Price is just a bit more than LHM+.

Suck/syphon/empty out most of the contents of the LHM reservoir, and replace with H'cage. Then bleed the system at the brake calipers, until H'cage emerges. Top up the reservoir to the correct level, and run the car on it for the recommended 1500-5000km. It is essentially LHM, plus cleaning agents, and will remove dirt and contamination without damaging the system. Afterwards, drain and refill with LHM+, and re-bleed until green stuff appears at the bleed screws.