Leaky ram and electrovalve!

Unread post by **Dommo** » 13 Feb 2010, 18:04

I'm not certain on how long it takes to sink but it's not long, and it's probably to the bump stops.

I'll have a look in a bit as it will have been parked outside for an hour or two.

If the clyinder is gone will LHM leak to the outside world or is it internal and has a return spigot?

Cheers.

Unread post by **CitroJim** » 14 Feb 2010, 15:14

Dommo wrote: If the clyinder is gone will LHM leak to the outside world or is it internal and has a return spigot?

Internally. There are two leakage returns on each cylinder boot Dom. If a rear cylinder is leaking externally then it's in a bad, bad way...

If you have not swapped the rear corner spheres then these are prime suspects as they can rupture on an Activa and you'll not really be aware of it just driving as the car will be predominantly in soft mode and therefore the rear corners will be doing damping duties only. This applies to Hydractive cars generally.

Easy to check for ruptured corners; remove a sphere and if LHM jets out of the damping hole and sprays a needle-fine jet for a distance of 6 feet or so then they're ruptured...

Rear sinks have nothing whatever to do with the anti-sink sphere. It's mis-named!

Xaccers · Unread post by **Xaccers** » 14 Feb 2010, 16:39

Jim, if they've ruptured, then what's pushing the LHM out?
I thought ruptured ones will pour LHM out if you hold them with the hole down, and if they're very flat they don't have enough pressure to push the LHM out within the system, but can once removed, giving the spray?

Unread post by **CitroJim** » 14 Feb 2010, 16:53

Xac wrote:Jim, if they've ruptured, then what's pushing the LHM out?

Well, all I can say is that on experience, rear hydractive ones do Xac

Remember the silver V6 we broke? That one had been depressurised for months before I cracked off the rear spheres and I was astounded at the powerful needle-fine jet that came out and also for how long both in time and distance.

Very small hole and 400cc of LHM trapped behind it is enough to do this.

Non hydractives and accumulators have bigger holes and thus will pour out...

As I say, from experience this

DickieG · Unread post by **DickieG** » 14 Feb 2010, 20:43

Xac wrote:Jim, if they've ruptured, then what's pushing the LHM out?
I thought ruptured ones will pour LHM out if you hold them with the hole down, and if they're very flat they don't have enough pressure to push the LHM out within the system, but can once removed, giving the spray?

Whilst the diaphragm is ruptured the LHM within the sphere is still under pressure and due to the rupture there will be more LHM within the sphere which takes a fair while to flood out through the small damper hole, a sure sign of a ruptured sphere is one that continues to be tight to undo well beyond the initial "cracking".

Xaccers · Unread post by **Xaccers** » 14 Feb 2010, 20:57

DickieG wrote:
Xac wrote:Jim, if they've ruptured, then what's pushing the LHM out?
I thought ruptured ones will pour LHM out if you hold them with the hole down, and if they're very flat they don't have enough pressure to push the LHM out within the system, but can once removed, giving the spray?
Whilst the diaphragm is ruptured the LHM within the sphere is still under pressure and due to the rupture there will be more LHM within the sphere which takes a fair while to flood out through the small damper hole, a sure sign of a ruptured sphere is one that continues to be tight to undo well beyond the initial "cracking".

With the system depressurised, what's pressurising the LHM in the sphere if there's no diaphram?
My mind is telling me:
New sphere, when the system is depressurised, the gas is able to expand pushing all the LHM back through the pipes.
Nearly totally flat sphere, when the system is depressurised, the gas isn't able to fight against the resistance in the pipes and so retains LHM. When it's removed the only resistance is from the hole, so the gas is able to expand, spraying the LHM out.
Ruptured sphere, when the system is depressurised, the sphere is full of LHM, at the same pressure as the pipes, so when removed LHM runs out, just as LHM runs out of the sphere's socket.

DickieG · Unread post by **DickieG** » 14 Feb 2010, 21:20

Xac wrote:
DickieG wrote:
Xac wrote:Jim, if they've ruptured, then what's pushing the LHM out?
I thought ruptured ones will pour LHM out if you hold them with the hole down, and if they're very flat they don't have enough pressure to push the LHM out within the system, but can once removed, giving the spray?
Whilst the diaphragm is ruptured the LHM within the sphere is still under pressure and due to the rupture there will be more LHM within the sphere which takes a fair while to flood out through the small damper hole, a sure sign of a ruptured sphere is one that continues to be tight to undo well beyond the initial "cracking".
With the system depressurised, what's pressurising the LHM in the sphere if there's no diaphram?
My mind is telling me:
New sphere, when the system is depressurised, the gas is able to expand pushing all the LHM back through the pipes.
Nearly totally flat sphere, when the system is depressurised, the gas isn't able to fight against the resistance in the pipes and so retains LHM. When it's removed the only resistance is from the hole, so the gas is able to expand, spraying the LHM out.
Ruptured sphere, when the system is depressurised, the sphere is full of LHM, at the same pressure as the pipes, so when removed LHM runs out, just as LHM runs out of the sphere's socket.

You're thinking along the same lines as me there Xac, when the sphere is under pressure/good condition the volume of LHM inside the sphere is minimal.

addo · Unread post by **addo** » 14 Feb 2010, 21:22

The spheres, when ruptured, are barely leaking. Bit like a tyre with a small nail in the tread - only the tiniest leak, not a rush of air. It's not an instant purging of gas contents as pressures either side of the diaphragm are more or less equal.

So - some gas comes out, and aerates the fluid. Some fluid goes in; eventually a decent quantity. A blown sphere also feels appreciably heavier than a good one.

Unread post by **Dommo** » 16 Feb 2010, 17:58

Bit of a delay here I know, but from what I can tell from the few times I've left it parked in the normal driving position everything seems fine regarding sinking. Whether it makes a difference when just one person is in (and then gets out) I'm not sure. I'll try leaving a door open when turned off to see if it's the hydractive ness that stops it sinking. As it takes about 15-20 seconds to sink/height correct after people get out of the back, leaving only 10 seconds of 'sinking' before the hydractive ECU turns off?

One other thing that may be linked. When I park the car on service low, and come to it a good few hours later, overnight for example. Opening the door and it activating the hydractive ECU makes a banging sound from the rear. To see what it was I just stood by the rear wheel, opened the door and sure enough it banged, the rear of the car raises up slightly when it happens. It's certainly doing something it shouldn't so I'm a little worried.

Any ideas?

Unread post by **CitroJim** » 16 Feb 2010, 21:45

Dommo wrote: Any ideas?

Not yet Dom, except that it should not do that...

Questions to help mull this one over:

1. Have you replaced the rear corner spheres, the center hydractive and the anti-sink spheres?

2. Can you feel a distinct difference in rear end softness between hard and soft mode.

test like this: Switch off, get out and shut doors.

Bounce rear. keep bouncing until the electrovalve clicks off. At that point you should feel the suspension become noticeably firmer.

3. Have you ever heard that nose when doing Citarobics? Especially as the car begins to rise from it's lowest position.

4. Is there any play at all in your rear ram bush?

5. Can you provoke the noise by "exercising" the Activa system? Do that by pulling and pushing on the roll corrector linkage balljoints just visible in the rear of the front wheel arches. Do it with the car at normal ride height and with engine running. You should be able to make the car rock.

DickieG · Unread post by **DickieG** » 16 Feb 2010, 22:01

Dommo wrote:One other thing that may be linked. When I park the car on service low, and come to it a good few hours later, overnight for example. Opening the door and it activating the hydractive ECU makes a banging sound from the rear. To see what it was I just stood by the rear wheel, opened the door and sure enough it banged, the rear of the car raises up slightly when it happens. It's certainly doing something it shouldn't so I'm a little worried.

Any ideas?

Sounds perfectly normal behaviour to me, whenever I'm unlikely to drive one of my Xantia's for a few days I've always left them in service low position and just as you describe whenever a door is opened the rear of the car takes a little bunny hop complete with the sound of a bang as the Hydractive block opens. As a guide to it not being age related my VSX has done it from new

Unread post by **Dommo** » 16 Feb 2010, 22:21

I've not replaced any of the spheres, yet. I wasn't going to yet unless it felt like it needed them. The back end does seem fairly clattery over big bumps so I do think the rear corner and hydractive spheres need doing. I might try and make my own sphere pressure tester. As I don't want to replace spheres that dont need doing.

DickieG - it's definately a bad sounding noise isn't it. I might try and film it. I'm fairly sure it didn't do that prior to our messing about. But it would have previously leaked out some LHM from the activa system, would that release pressure from the circuit and stop it banging?

Unread post by **Dommo** » 16 Feb 2010, 23:12

And yes there is a definate stiffness change when the hydractive ECU turns off after 30 seconds.

I've not noticed it happen yet doing citrobics, only when opening the doors after it's been parked for a few hours on service low.

Unread post by **Dommo** » 31 Mar 2010, 12:17

Bit of a old topic to drag up here, but recently the front end seems to be the sinking end rather than the rear! Maybe if the rear corners spheres are ruptured they're now so full with LHM it's stopped sinking, and its the front corner sphere's turn to sink now

Here's what it looks like as soon as I've parked up

And here's what it looks like after being parked overnight:

I'll be doing the rear corners as soon as I get a tool made up...

Unread post by **CitroJim** » 31 Mar 2010, 12:37

Hi Dom,

That level of sink on an Activa is pretty normal in my experience. Both mine sink to the same extent as yours..

I'm not saying they all sink like this but certainly mine do and I know mine are both pretty good in the hydraulics department.

A bit of an Activa quirk I think.

Comments from other Activa owners?