10 minute Xantia mod....what a difference!

[Mandrake]

Thanks Si, that explains why no matter how much I try to set it up perfect the normal ride height is always different between service high and service low! Will get two for each end!

Cheers.

How much difference in height is there each way ? Its normal for there to be a small difference in height when it adjusts to normal height from either direction - anything under 10mm is fine, 10-20mm would be typical at the age they're at now, more than 20mm or so I would want to do something about it.

As well as the dog bone having slack the major cause is sliding friction in the pivoting parts of the linkage assembly due to rust - they have to be nice and free for it to work accurately. Any slack in the dog bone will combine with drag in the linkage as the rusty linkage will stick in place until the suspension moves far enough to take up the slack in the dog bone...

A properly free linkage is returned to centre by the spring when the dog bone is not pushing it one way or the other but a rusty linkage will not self centre and has to be "pushed" by the dog bone.

[isisalar]

Re Simon's post regarding air leaks in the tank to pump feed line. I replaced mine completely prior to doing the o rings in the pump, and it seems to be working perfectly. Also did same on the old VSX.
The elbows on the pump end and elsewhere are certainly weak points and trying to copy the original pipe run is almost impossible. I can only speak of the HDI and the 1.9 td but in both cases by re routing the pipe it's been a very simple and effective job. In both cases the elbows are completely unnecessary. Here's a couple of pics of the HDI.
https://www.dropbox.com/s/m5ttpnehfvrr8 ... .30.49.jpg" onclick="window.open(this.href);return false;
https://www.dropbox.com/s/t4npuk0jyuihu ... .31.11.jpg" onclick="window.open(this.href);return false;
On the HDI the tank end spigot is just a little too small, by less 1mm, to give a snug fit in the 1/2" fuel grade tubing readily available, so I built it up a little with a bit of PTFE tape, was going to use amalgam tape but the hydraulics place the bits came from recommended the PTFE. This is also used, internally, to seal the aluminium to brass reducer, necessary for the 3/8" tube going on to the pump, this was a good fit on the HDI. Obviously jubilee clips where necessary.
There's even a handy hook on top of the rad to tuck the pipe into and cable ties can be used to support if needed. I left the original pipe in situ, can always use if the other's leaking.
I originally tried Pirtek for the bits but they were unable to supply a suitable joiner at all, as luck would have it, next door to Pirtek were these guys http://www.hopespare.com/" onclick="window.open(this.href);return false; who had the bits to make up a good joiner,were cheaper, and a lot more helpful. They're only down South but may do a postal service.
Not sure if this would work on the v6 but hopefully this may help anyone whose Xantia feels like a skateboard over little bumps. Do the pump o rings as well, very easy too on the HDI, and all else being well, it will transform your car.
Cheers
Paul

[cc101]

Think I'm probably being a bit piccy as they are within tolerance!

[co04pow]

Just a quick message to say that I found this thread and thought that’s exactly what my car needs. I bought a V Reg 1999 2.0 Hdi Xantia exclusive about 2 years ago and had never been happy with the ride. Good on long journeys on the motorway and good roads, but horrendously harsh on the pothole and uneven surfaces of the totally destroyed Edinburgh roads that I travel every day. My previous 2.0 Hdi SX was great much softer. After replacing all 8 spheres, stripping both ride height correctors, stripping both electro valves, running hydoflush and the diode mod I was still not happy with the ride but lived with it for over a year. A bit of time off work lead me to do some more reading and found this thread. I have carried out more or less the same pipe fitment as Paul and cut the plastic return pipe inside the reservoir see pictures:
https://www.dropbox.com/sh/k67sivy7ywr1tpg/54NwByrzT9

The result is fantastic!!!! The harshness is gone. My daily drive to and from work is a totally different experience.

I have also had a rattle from the front end which I thought was either drop links or engine/gearbox mounts made worst by the harshness of the ride. I then found the thread to with the brake calliper retaining springs made by Citroen to fix this problem of the 2.0 hdi Bosch callipers. I have checked and they do have play in them on the sliding pins. I called Citroen and they want £60.17 for the 2 bits of sprung metal. NOT happening! I am going to look into calliper rebuild kits. Has anyone come across these?

Anyway thanks to all involved in this thread it has made me a happy man.

Thanks

Owen

[cc101]

Excellent, that's what makes these forums great!

[Mandrake]

Great to hear of your success Owen How long has it been since you did this mod ?

It sounds like you were very thorough in ruling out all other possibilities first (spheres, sticky height correctors, electrovalves, diode mod etc) to no avail - much like me with my previous Xantia a number of years ago where I did all that but even went as far as replacing the rear suspension arm bearings, (which turned out to be fine!) and front struts (whose shafts were worn through the hardening at the normal ride height position) and still had intermittent severe ride harshness over broken surfaces until I started experimenting with the air bubble issue.

Although I never got that Xantia 100% (I don't think the U-tube I fitted works as well as just cutting the pipe short, and there may have been other issues) when I did the mod on my current Xantia the ride was velvety smooth and completely free of harshness for three months straight, but then started to deteriorate again as a slight air leak on the inlet hose near the pump manifested. (Visible weeping of oil at the joint) I replaced and tightened the clamp and the ride was smooth again for about 6 weeks then started getting worse again, and once again the joint is weeping slightly.

I've just ordered some new hopefully better fitting hose and I'm tempted to at least temporarily as a test replace the entire length from tank to pump as one piece - on the V6 the pump spigot is the same diameter as the tank spigot so one length of 12.7mm ID hose should work without needing a size step down joiner. It will be interesting to see if it is indeed an air leak that made the ride get so bad recently, its got bad enough that I thought the front spheres were shot.

Interesting you say that the ride on your Hydractive car was so much worse than the SX - although the standard models can suffer from air bubbles as well (cc101's car is not Hydractive) I'm pretty sure that the Hydractive models are more prone to harsh ride due to air bubbles for a few reasons.

One is there is a lot more pipe length and diameter between the struts and height corrector - so far more oil volume and piping for bubbles to get caught in - and it's less able to self bleed when the suspension is lowered. (The air bubbles have to be forced all the way from the struts to the height corrector to bleed, the long, large diameter pipes on the Hydractive take a much larger flow volume to push that air all the way through to the height corrector)

The second is that I think the wheel oscillation that naturally occurs when you hit a broken surface causes the large pipes that run from the front strut tops along the wings down to the hydractive regulator to "hammer" against the chassis, passing the shock into the body. Especially if the pipes are not bolted to the wing properly or the steel pipe is out of its plastic guides. (Especially under the battery mount)

The final one is that I think enough air does actually start to cause the hydractive control block to malfunction - instead of staying locked in hard or soft mode as directed by the electrovalve I think it will sometimes chatter back and forth with suspension oscillation since the control pressure from the electrovalve is not completely incompressible when laced with air.

If the valve is bouncing back and forth between soft and hard positions 10-15 times a second during a "wheel hop" oscillation, (self resonance of the suspension springing and axle/wheel mass - typically around 10-15 Hz) that would transmit a very significant repetitive jolt into the suspension/chassis during each wheel oscillation.

By the way I've only driven in Edinburgh a few times but the potholes can't be worse than those in parts of Glasgow - entire cars can fall into potholes here and go missing for days...

[c.morewood]

Thinking outside the box, literally ... would one of these work in the return line, rather than butchering the lhm box spiggot?

[Mandrake]

Great. Fantastic. What is it ?

[electronmirror]

It's an air eliminator used in hydronic heating/cooling systems

[c.morewood]

Its an air bleed you'd get in your central heating/solar heating system.. it bleeds air out of the system..I know this one is probably only good for water, but maybe there's one that's oil compatible?

Beat me to it

[c.morewood]

This got me thinking that ther must be a commercial oil air separator.. there are but much too big for this requirement. I ran a search on EBay and came up with this.
http://www.ebay.co.uk/itm/390690984189? ... 1423.l2649" onclick="window.open(this.href);return false;
Would this work to separate the LHM and air?

[Mandrake]

The problem I can see with an external air separator (apart from where do you squeeze it in beside the tank ? Space is limited and the pipes have pre-formed bends) is that even if the oil flow through the pipe is air free the high velocity of the oil entering the tank and the small catchment area inside the filter means that the oil is highly agitated (vortices circulating within the filter) causing the oil to become aerated within the tank itself.

I think part of why cutting the return pipe short works is because it keeps this turbulent vortex higher up in the oil away from the bottom where the pump draws its oil from - the oil and air bubbles swirl around in the top of the tank (with bubbles escaping through the oil surface) but the bottom where the pump pick-up is is relatively calm and free of bubbles.

It's not clear how much of the air bubble problem is this turbulence within the tank and how much is air bubbles in the return line - I think it's a bit of both. An external air separator only addresses one of the possible causes.

The ideal solution would be a redesign of the tank - the small size and shape of the return filter, the layout of the tank and return and pickups is not well designed and does not have sufficient de-aeration ability for the flow rate. If you look at the tank in an older Citroen (GS/CX vintage) the tank design and internal layout is totally different, not to mention the lack of anti-sink makes the suspension fully self bleed each night. That's why it was never a problem until the Xantia.

Anti-sink severely limits the self bleeding ability of the system combined with a poor tank design that doesn't give sufficient isolation between return and inlet. (Although there are two gauze filters in between the return and inlet they are very close together in the tank, only an inch or so apart, near the bottom) All you need is a bit of extra air to get in somewhere like a leaky return line and start circulating around and around and things spiral out of control.

There should have been a partition between the inlet and outlet in the tank with a convoluted path for the oil to flow around the long way - or inlet and outlet on opposite sides of the tank.

[c.morewood]

So Simon, you're saying that if there was a way of separating the in and outflow that the bubbles would not be drawn into the inlet?
Would it now be as easy to trim a flat piece of flexible plastic (so that it fits through the hole) to the shape required and place it between the in and out and make sure it reaches the bottom of the tank and most of the way to the sides, thus seperating the flows.
I haven't studied the shape of the tank that much.. only had it apart to clean it once almost a year ago.
I do have an air leak on the Y return connectors above the rear subframe, caused by pulling too hard on the returns when trying to connect them to the bellows of the rear suspension cylinders (what a fiddly job) which I will hopefully be sorting in the next month or two.

Chris

[Skull]

Mandrake

Then yesterday I decided to fully de-pressurise the suspension and leave it right down over night. Today I then started the car, lifted it to normal ride height and drove off. Eureka! The ride was back to perfectly crash free, very smooth, and very stable and well damped at high speed. In fact slightly better than it was after I first did the modification.

I'm going to try this once my current problem is sorted (without the pipe modification) just leave her in low overnight.

Even though I've changed all my spheres which was a massive improvement I have never had, what I would call a [so called] 'magic carpet ride' around town.

[chinkostu]

Just to bump a massively old thread:

had issues with stiff riding in the old girl. had a few hours of really good riding, mostly after the new front spheres, but would consistently worsen until it was like riding a normal car. even a citroebic and bleed wouldn't make it any better (one time worse!)

went ahead and did this mod aswell as cleaning the filters (which had lots of little black specks stuck to them!) along with renewing the hose clamps on the inlet and return pipes (the other smaller piping i managed to reuse the old clips which held really well) and giving it a good citroebic session. the car feels better now, definately on a par with when the systems been running well. still get a thud over ridges but definately feeling it less. the tank looks a lot calmer now too. i'll give it a week to see if it worsens.

the downside? i think the rear spheres are getting a bit tired now as when you hit a ridge you hear it more when the rear wheels go over it!