Activa front suspension misbehaving

[Sl4yer]

The component parts of my Activa's clutch recently decided that they didn't get along any more, and failed suddenly on the 2nd January. (To be fair, there was a warning, consisting of a strange vibration when taking the clutch up. This started the day before the failure - one to watch out for if you're driving a larger engine Xantia or early C5).

Anyway, when I picked up the car following the clutch job, the mechanic (who has owned various DSs and CXs in the past) mentioned that the front spheres were on their way out. I didn't pay too much attention - I know the Activa won't ride as well as he might expect. But the ride did feel a little choppy when I took the car home.

A couple of days later, I felt the front sink suddenly when driving. I assumed that this (and the poor ride) was probably due to the dog-bone being displaced during the clutch replacement, and took it back to the garage. They checked the dog-bone, and also that the height correction was working. I'd been unable to check the front, since it felt very firm and I didn't want to ruin the bonnet (there was a clue in that). The mechanic spoke to the local Citroen dealer, who said it was probably because the struts were worn... After a check of various posts on here, I'm sure that's not causing the issue.

So, the ride is often hard. I'm sure it's sticking in firm mode (the ride isn't ALWAYS hard). I'm sure the front dropping is when the front electrovalve actually opens after a long period of being stuck in firm mode - the drop happened near home yesterday, and after a slow drive back the front of the car felt as it should.

Sometimes the front will drop when I open a door, sometimes it will happen when the system is pressurising, sometimes it seems OK. Interestingly, I put the Lexia on last night, and the front dropped as soon as I selected the suspension ECU. Clearly something was cycled which triggered the front to drop (opening the doors hadn't done anything). I went for a drive with the Lexia attached, and the ECU is responding as expected. No funny sensor readings, no sign of the electrovalve being disconnected. The car had an e-crofting diode kit fitted about 5 years ago, so it's unlikely that faulty diodes are the cause (I can hear the buzz and click from the front valve). The Activa system works OK.

So, the ride can be fine, but the front is often staying firm when it should have switched back. What course of action should I take next? I tempted to Hydroflush- I've never used it in the 6 years I've had the car (but the LHM has always been kept fresh by various leaks! ). If it's not crud in the system somewhere, I guess the electrovalve and pressure regulator are the next suspects?

Thanks,

James

[CitroJim]

One cause of this can be low hydraulic pressure. The front is sensitive to it as the electrovalve needs both an electrical signal and hydraulic pressure to operate it to the soft mode.. The hydraulic pressure has to overcome the combined resistance presented by the corner and hydractive spheres and this is considerably more than the rear...

I'd get the main pressure checked by popping a pressure gauge on the regulator output and making sure the regulator cuts out at 170 bar and cuts in at 145 bar. Over time the regulator springs weaken and the cut-out pressure falls. Activas are sensitive to having the right pressures.

Strut wear is given away by rapid sinking after switch-off in the normal height position but no sinking from high...

[Sl4yer]

Thanks Jim. I'll give that a go, rather than Hydroflushing.

James