help with possible air in suspension on xantia

[elma]

Hi, car is a 1.9 td vsx L reg xantia.
Have been gradually doing up the car and it was quite good, however I decided to replace the rear centre sphere yesterday.
Fitting the new sphere was no problem and all went as normal until the car was repressurised.

Now the car behaves badly when moving up and down. What I presume is air is moving around the system and the car will jump when it moves. Often the back is jumping in the air when the car is faling. Also there is a strange noise which sounds high pitched and whirring. The noise apperars to be from the height corrector and alternates between front and rear. It can happen on both ends at the same time as well..
The back of the car is now very saggy and can be bottomed out just by pushing down.

To bleed the system I did as per haynes. Car went up and down a lot, although the symptoms of air didn't go away like normal. Raised all 4 wheels off the ground. Put a bar on the brake pedal. Bled fl, fr, rl, rr.
While working I was careful to open the door every couple of minutes to initiate soft mode.

I'm very confusded and would appreciate any help, cheers.

[RichardW]

Ah, the good old hydractive leap. Pretty alarming first time it does it to you 8)

What has happened is that your centre sphere was probably totally flat before, but now has the capacity to store loads of LHM under pressure. The hydractive valves are not quite working right, and hence the pressure between the corner spheres and the centre spheres can become mis-matched - particularly if you just had it in high. When the ECU decides to open the HA valve, the high pressure LHM rushes out of the centre sphere to balance the system pressure across the 3 spheres, and BOING, up goes the suspension - like 3" in the blink of an eye The whining / clicking you can hear is the hydractive valves switching.

The first thing I would do is fit additional diodes across the supplies to the HA valves - there was post a few weeks back about this very thing. Simon (Mandrake) will be along later and explain all

With a good centre sphere, the rear will be very soft in soft mode this is partly why it switches to hard mode when you accelerate, and why the ride is so much better in a hydractive car than a 'normal' Xantia.

[CitroJim]

Excellent daignosis and description of the problem Richard As we await Mandrake, this thread:

http://www.frenchcarforum.co.uk/forum/v ... hydractive

Details the experiences with a ready-made hydractive repair kit that avoids soldering if you're not confident to fit diodes yourself, along with some background information on the problem.

With a good centre sphere, the rear will be very soft in soft mode this is partly why it switches to hard mode when you accelerate, and why the ride is so much better in a hydractive car than a 'normal' Xantia.

Yes, absolutely I drove our TD for the first time in months this evening because SWMBO was complaining about the brakes. Front pads worn right down to nothing! I digress, the ride difference between hydractive and non-hydractive is unbelievable. I'd forgotten just how different it was. They roll alarmingly after an Activa as well

[Mandrake]

Now the car behaves badly when moving up and down. What I presume is air is moving around the system and the car will jump when it moves. Often the back is jumping in the air when the car is faling.

I presume you mean this is happening while doing Citrerobics going from maximum height down to normal or minimum height ?

If so this is something that shouldn't happen in theory but a lot of Xantia's (including mine) do it, it's no cause for concern, and Richard has done a good job describing it.

Also there is a strange noise which sounds high pitched and whirring. The noise apperars to be from the height corrector and alternates between front and rear. It can happen on both ends at the same time as well..

This is normal, you probably just didn't notice it until you went looking for "problems". It comes from the Hydractive 2 electrovalves which are screwed into the side of the block that you fitted the sphere on. Both front and back make the noise but the noise does change character and intensity a lot depending on battery voltage so you sometimes may not notice it. Again nothing at all to worry about.

The back of the car is now very saggy and can be bottomed out just by pushing down.

This too is normal - most likely the sphere you replaced was totally flat so the springing would have been very firm. Now it's as it should be - I can bottom the rear suspension on mine just by leaning on it let alone sitting on it

Hydractive 2 rear suspension is VERY soft. This is why the computer switches to hard mode for a few seconds when you accelerate off the mark, otherwise the suspension would bottom completely due to the acceleration induced squat.

To bleed the system I did as per haynes. Car went up and down a lot, although the symptoms of air didn't go away like normal. Raised all 4 wheels off the ground. Put a bar on the brake pedal. Bled fl, fr, rl, rr.
While working I was careful to open the door every couple of minutes to initiate soft mode.

I'm very confusded and would appreciate any help, cheers.

Since none of the symptoms are symptoms of air, thats why they didn't go away. It sounds like you just havn't seen the car operating with all the spheres gassed up before and weren't expecting it to be as soft as they actually are.

The more important thing is how does it drive ? If the ride is really good and the handling feels good as well then you are probably just chasing your tail looking for problems that don't exist

Regards,
Simon

[elma]

Cheers guys, you've made some useful points. Still not got to the bottom of this though.
After playing with it yesterday I think I'm a litlle closer.
The noise is definetly a new one, it is not the electrovalve, I am familier with that one. It is much louder and appears to be coming from the height correctors.

The car is still behaving terribly and the rear end is far to saggy and rolly.

By fiddling I have decided that the vsx is not switching into hard mode at the rear when driving. However if the car is left off for a few mins it does go into hard.

Another symptom is that the suspension light (not the stop light) has never worked on this car, even with a brain from the old car which I know works. I've never been happy about that.

I've removed fuse 5 for now so its an sx for a bit until I can get to the bottom of this.; With the vsx fuse removed it handles ok, just a bit bumpy.
WIth it working ok like this and being stuck in soft at the back when hydractive is connected I am suspecting the bit that the rear centre sphere screwas into as being faulty.

[elma]

I have also noticed now that the accelerator sensor on the pump is missing, could this be a cause?

[philhoward]

Accelerator sensor on the pump? There was one on the pedal on my VSX, but 99% sure it was just for the glow plug timer. The one which (I think) does make a difference is the steering sensor - stifferning it up when cornering.

If the light doesn't come on - does it illuminate (dimly) with the sidelights?

[Mandrake]

Cheers guys, you've made some useful points. Still not got to the bottom of this though.
After playing with it yesterday I think I'm a litlle closer.
The noise is definetly a new one, it is not the electrovalve, I am familier with that one. It is much louder and appears to be coming from the height correctors.

Hmm... almost impossible that the height corrector could make such a noise - after all its a purely passive hydraulic component... no electronics involved

The only noise a height corrector could make would be a hissing noise with oil running rapidly through it while lowering the height. I think you're chasing ghosts trying to find a noise coming from the height corrector...

The car is still behaving terribly and the rear end is far to saggy and rolly.

By fiddling I have decided that the vsx is not switching into hard mode at the rear when driving. However if the car is left off for a few mins it does go into hard.

You are aware that soft mode is the normal mode to be in while driving right ? Only fairly tight cornering will switch to hard mode briefly during the corner. It's not normal for it to switch to hard on every corner.

Are you sure that the rear strut spheres are the correct ones ? Have you checked or replaced them ? If the back is extremely soft and rolly its quite likely that someone has put standard Xantia strut spheres on instead of Hydractive ones.

When the centre sphere (which you just replaced) is faulty this would give an acceptable ride. (but no change between hard/soft) When the centre sphere is good AND you have standard strut spheres fitted instead of the correct ones it would be FAR too soft and underdamped.

I'd suggest you pull the strut spheres off and check the part number (or get the number without removing them if possible) and post it here - there are folks who have the part codes for Citroen and 3rd party spheres that can tell you immediately if they're the wrong ones.

If you can't find a code, measure the centre damper hole by inserting some tiny drillbits - Hydractive rear spheres should have a hole that is 0.5 or 0.6mm, non-Hydractive spheres will be between 1.0 and 1.2mm.

If you find they have a hole 1.0mm or bigger you've found your problem. (Wrong spheres) Also check the pressure stamped near the filler cap - it should be 30 bars for a hatchback and 40 bars for an estate. If its 40 and your car is a hatchback that will also make it too soft.

Another symptom is that the suspension light (not the stop light) has never worked on this car, even with a brain from the old car which I know works. I've never been happy about that.

You mean the one on the Hydractive switch ? Does it come on dimly with the headlights ? If not its probably just the bulb blown! It's got a little grain of wheat bulb in it which can be replaced but it is quite tricky to dissasemble the switch...

I've removed fuse 5 for now so its an sx for a bit until I can get to the bottom of this.; With the vsx fuse removed it handles ok, just a bit bumpy.
WIth it working ok like this and being stuck in soft at the back when hydractive is connected I am suspecting the bit that the rear centre sphere screwas into as being faulty.

No, I doubt that, it sounds like its switching modes just fine - as I said, it tries to keep it in soft mode as much as possible and only resorts to hard mode in specific circumstances.

The problem is very likely your soft mode is too soft due to someone putting the wrong strut spheres on.

Regards,
Simon

[Mandrake]

Accelerator sensor on the pump? There was one on the pedal on my VSX, but 99% sure it was just for the glow plug timer. The one which (I think) does make a difference is the steering sensor - stifferning it up when cornering.

The accelerator sensor on the pedal is part of the Hydractive system - and allows the computer to sense acceleration. It's mainly used to switch to hard for a few seconds while pulling away from the lights to prevent the rear suspension bottoming

The rest of the system will still operate without it, but it no longer responds to throttle movements...

Regards,
Simon

[elma]

I think we're on to something here. The car didn't have hydractive at first. Had to replace the fuse, then lots of pipe after the new fuse. If someone had disabled the hydractive then they would maybe put on the normal spheres. Rear two are the only ones not replaced so will try.
Think that new sphere may have been wrong as well. Hole was bigger than 0.5 mm ( i think) I wuill check the code numbers and see.

Thanks again

[Mandrake]

I think we're on to something here. The car didn't have hydractive at first. Had to replace the fuse, then lots of pipe after the new fuse. If someone had disabled the hydractive then they would maybe put on the normal spheres. Rear two are the only ones not replaced so will try.
Think that new sphere may have been wrong as well. Hole was bigger than 0.5 mm ( i think) I wuill check the code numbers and see.

Thanks again

Yes,

If the Hydractive system was disabled they may well have put "normal" spheres on the rear corners to bodge around it.

Sorry, I wasn't clear about the hole sizes - I was refering to the rear corner spheres only - it's normal for the rear centre hydractive sphere to have a large hole - it's about 4mm and there is no damper valve in the neck, (hollow neck just like an accumulator) so don't worry about that one...

Regards,
Simon