xantia suspension problems hydractive version

[ianb875]

Hi. I have just bought a 1998 xantia exclusive with hydractive. Car build no is 8093 and mileage is 95k, with service history.
I have issues with the suspension
1 When car is left overnight on normal setting, the back suspension is down by next morning.
2. Same thing happens if car is on high setting overnight.
3. On normal , non sport, setting, the suspension is quite firm in normal use but press 'sport' button and it softens.
Car had not been used for a while when I got it and suspension setting changes could cause a bit of a jolt as car transitioning but that is now ok
I have looked under the car for leaks or damage, but nothing found and mechanisms are greased.
I have 2 other xantia s, both non hydractive and they are fine. I have a feeling I read somewhere that there were 3 changes made to early hydractive xantias, before they behaved themselves.
I hope someone can explain what the hydractive one is playing at!

[aerodynamica]

Hi Ian, it's hard to say for sure without seeing the car but a 1998 build car will have the original type of Hydractive regulators front and rear. These rely on an individual high pressure feed from the main system to power the opening of each front and rear electro valve that switches from firm to soft suspension. The later revision had simply different pipe union type and the third revision (post 1999 some stage) had a different internal arrangement in the hydractive regulators where the external feed was eliminated. That was a simplified version.

Occasional hydractive stiffness can be caused by either hydraulic faults or electrical faults.

Rear sinking overnight.
The car should have anti sink suspension and the rear height dropping overnight suggests an internal leak. It is not unknown for the anti sink valve itself to wear out. It could also be a rear suspension strut has worn so much that the anti sink doesn't prevent it sinking. An indication of that would be excess LHM in the rubber boot of one of the suspension units.
A failed Hydractive regulator might cause heavy internal leak although I'm not sure how to test that apart from finding LHM constantly leaking from the small rubber leak off hose on the end of the hydractive electrovalve solenoid. You can pull this off and find it should only have a small oozing of LHM. Some LHM Citroens suffered from rear suspension drop caused by a worn brake valve (mine did a year ago) although I think the anti sink valve separates the rear suspension from the rear brake circuit on anti sink cars (my Xantia was a sinker) so I wouldn't have suspected the brake valve for yours. At least not the prime suspect.

Suspension jolting up or down:
A large jolt on an earlier Hydractive car can be from the pressure in the suspension cylinders of one axle being higher than the pressure needed from the main line pressure to open an electrovalve and causing a large difference between the corner spheres and the center sphere that suddenly connect after some threshold and cause pressure to equalise causing either a jump up or a sudden drop. On early cars with the Flow Divider Valve for the PAS a fault with the FDV sinks pressure from the high pressure pump and lowers the pressure available to the main accumulator. In times of higher demand the pressure can drop enough to cause the pressure to the hydractive units to dwindle and renders them sticking in stiff mode (even for short spells) because there's not the pressure to hold them in the open (soft) state. Your car wouldn't be prone to that but bad pump output caused by another factor could do such as a slipping Aux belt or the HP pump sucking in air from bad pipe end spigot sealing or a pump that is worn out.

As for the stiff ride when it's in non sport mode:
Separately the electrical power to the front and rear electrovalves needs to be confirmed. Open a door and you should hear a click and then a low pitched continuous tone from the F &R electrovalve solenoids. This should have the car in soft mode and with the engine then running the hydraulics should pressurise to open the F&R valves to connect all spheres in an axle to put it in soft mode. The system needs both electrical power to each electrovalve AND enough hydraulic line pressure to work the valve. The front and rear should be very soft to push with the engine running and the car stationary. It can be possible that the one of the electrovalves is working but not the other so you'd still hear the sound from one of them but I think the ECU detects a fault and when it receives speed information from the gearbox sensor (car driving) it faults out and switches to safe (stiff) setting. Should say, the pressing of the sport mode button shouldn't make a difference to that. Another observation: if you are getting a jolt up or down in the suspension that suggests that the electrovalve (at least the one on the axle that jolts ) actually does work electrically.

It's possible you have a faulty rear hydractive regulator valve that's worn. This could also perhaps cause the rear sinking issue if it's internally leaking enough I suppose. Or the diode inside the solenoid has popped needing an external diode wired in. Popped protection diode in the solenoid causes it to fail to stiff mode by having the solenoid switched out of circuit by high residual voltage that's no longer eliminated by the diode. They used to sell kits for this diode repair.

A final thought is that perhaps one of the center (softness) spheres is flat? Do you know the sphere(s) ages? Also the anti sink brake accumulator sphere at the rear being flat wouldn't help the anti sink system either.

Anyway, it's just suggestions from someone who has suffered several hydractive 1 and 2 cars and gone through them each over the years with their craziness!

[myglaren]

Or the diode inside the solenoid has popped needing an external diode wired in. Popped protection diode in the solenoid causes it to fail to stiff mode by having the solenoid switched out of circuit by high residual voltage that's no longer eliminated by the diode. They used to sell kits for this diode repair.

There was someone called Brian Pimmer used to attend all the Citroen rallies and had those kits, among other things.
Haven't seen him for ages but the kits he sold were from E-Crofting.
May be of use if that is your problem.
There is a guide somewhere on the forum to do this yourself if you are happy mucking about with diodes and soldering irons.

[aerodynamica]

I think Brian passed away last year. A really nice chap. He also supplied the stainless steel side trims for xantias

[xantia_v6]

I think that the sinking needs to be addressed before investigating the ride quality. Statistically, it is most likely to be a failed rear strut, monitoring the flow in the rear strut return pipes is a fairly easy diagnostic step.

[ianb875]

Thank you all very much for your input. It certainly seems that I should investigate rear end sink first as suggested, and will start on that now with some very useful info to guide me

[Mandrake]

I think that the sinking needs to be addressed before investigating the ride quality. Statistically, it is most likely to be a failed rear strut, monitoring the flow in the rear strut return pipes is a fairly easy diagnostic step.

Yes, or a faulty anti-sink valve, although that seems fairly unlikely. Not much else that can cause an anti-sink model to sink so quickly overnight.

[Rhothgar]

Sad to learn of Brian’s passing.

I was just searching for replacement items for Xantia…