Hi All,

Like I suspect many XM owners, I've been trying over recent weeks to diagnose a harder than expected ride (only had car a couple of months, was like it when purchased). I've had the corner and accum. spheres checked out and repressurised, bypassed the ECU problem areas with Roy Mackay's magic box, run a diagnostic test on the ECU (one steering sensor fault cleared), and am now considering flushing the hydraulics and replacing the LHM. Note that the ride is not boneshaking, just a bit, well, unimpressive. The 2 Citroen specialists I took it to thought it was fairly normal, but the car seems to dive into potholes and jump over speedbumps rather harshly for ``The Ride of Your Life''.

Now I've read a few postings on here about the subject and what I want to know is this: Does anybody have firsthand experience of a DEFINITE IMPROVEMENT in the ride as a result of a flush and new LHM?? Most results I read of seem rather ambiguous, and I need to be convinced it's actually worth it. And which would you tackle first -- LHM or checking out the centre spheres?

Matt

Hi Matt,

I'm not offering an opinion on hydraflush, but I see that you've had the corner and accumulator spheres regassed. You have missed out the two most important spheres where ride comfort is concerned - the front and rear hydractive spheres. Change those and I'm sure you'll see a vast improvement.

Derek

I agree with Derek the centre spheres aere the most important for the ride quality. I had a friend who used the hydraflush on his Xantia and the biggest difference he noticed was that it rose up in the morning far faster. The thing is you don't know if it was the hydraflush that did it or just new lhm fluid.

Hi all,
Hydraflush- does it or does it not? I have to agree with the general concensus in that no discernable difference is noticeable, but again i stress the continuous maintenance aspect of it's use- and the centre spheres certainly change the ride characteristics for the better.

Hi All

I suspect that one of the benifits of using Hydraflush is that it encourages you to do 2 fluid changes in quick sucession and this is more likely to clean the system than just a single LHM change.

Regards

XMexc

Definitely check the middle spheres, no point doing anything else if those are low on pressure -they offer most of the softness on an hydractive car-. I'd say change the front one which is easy anyway, and see what difference it does, if it doens't become a magic carpet, your problem is elsewhere...

I would probably do the hydraflush as well anyway, but this is not supossed to make your suspension softer in a direct manner, i.e. from the moment you put it -it might have an effect on the long run if your hydractive does not work because of dirtiness which the hydraflush will manage to wash away-. BTW, LHM is supposed to be changed every 60,000kms (about 40,000mls?) and the 2 filters on the LHM tank cleaned every 30,000kms. LHM+ has better behavior in temperature changes (more stable viscosity) compareded to LHM, but any will loose its mechanical characteristics after the prescribed period of use.

regards
George

There's an easy way to see if your middle sphere is very low on pressure, provided your electronics work: one of the fuses in the lower aprt of the dash cuts off the suspension ECU and puts car in "hard" mode. You should feel a distinct difference when trying to depress the front wing -bonnet of the car, engine running, between fuse-in-place / fuse-off. If your middle sphere is OK you should be able to depress easily the front a good 5-10 cms, and only about 2cms with the fuse off. Numbers are not exact but u see what I mean. If you don't perceive a clear difference between the 2 states by the 2nd attempt -it won't need any introspection, difference is obvious- then either 1/ middle sphere is very low on pressure, or, 2/ your hydractive doesn't work electricaly despite what the garage told you.

A way to make sure your hydractive is OK electronically is: on the suspension ECU, on black or green plug (if I'm right), put a £5 voltmeter on pins 1 (front electrovalve) and 2 (rear), and earth somewhere in engine bay; engine running, it should read not less than 2.7-2.8 volts. I got to the current just by needling the cable, you might already have some contact surface available on the cables required since u have put Roy's kit. If it reads 0 it means your ECU is putting suspension in hard mode permanently -prob the faulty sensor-. If u had a diode problem it would read 1.8-1.9. If u find it to read around 2.8+ with car static, this doesn't mean that it couldn't stick to hard as soon as you set off and e.g. turn steering. Only way to be 100% sure is bring voltmeter with you in car and drive around. Starting point should be 2.8+, then if you activate "hard" mode it will drop to 0 immediately, then after 1-2 secs it will jump to 12volts for half sec, then gradually down to 2.8+, where it wil stand till you reactivate the hard mode with some action of yours.

So, plently of choices to start diagnosing the origin of your fault...

G

ps. relevant fuse No. is described in the car's manual.

Since hyfraflushing both my XM's I've noticed the electrovalves 'clunk' more loudly than they did before. As for suspension softness, you don't notice any immediate improvement and it seems to take a good few hundred miles before anything happens. This makes it very hard to compare - much the same as the gradual ride degradation as spheres go flatter but the other way round

In my limited opinion the proof in the pudding is the amount of crud that sits in the filters after running hydraflush. I'd put two lots of clean LHM through mine and nowhere near that amount of crud came out. If you end up using the stuff - I personally think it's quite cheap from GSF (don't forget your 10% discount card from XM-L) - you will be surprised at how quickly it changes from clear light brown to dark cloudy brown as it cleans.

Get your centres checked / changed first though, if you're on a budget.

Wirdy, sorry to deviate from the thread but how do I get my discount card? I've never seen anything on XM-L

The only effect I have observed from using hydraflush is cleaner LHM, but of course a by product of this is that the filters stay clean and that can have a marked effect on the flow rate.

Also I echo what has been said about the centre spheres, if they are flat, changing the outer ones will make very little difference.

Peter.N.

What about those little ball bearings? Do they get crammed up with crud which hyrdraflush might release? I was trying to understand a couple of PDF's about Hydractive 2 recently and although still somewhat confused they seem quite important to the correct operation.

Is cleaning the tank filters as effective as replacing them?

How do you guys get the old LHM out? Not thru the brakes surely? Someone mentioned siphoning?

I'd prefer to leave this stuff to the indies but my old one especially gotta be done on the cheap, and the new one has yellowy LHM according to the indie. Gonna try and do the front spheres on the new one myself I think, and this LHM change on both if its not too difficult.

regards

To which bearing u refer?
G

Replacing the lhm is explained in the Haynes Manual. Basically though just put car into lowest suspension setting and then remove the lhm tank. Unclip the hoses to be able to get the filter/filler cap out of the way (not all need undone and I would suggest not doing the feed to the pump) and then pull the clip at the bottom front left out to release the tank. With the car at the lowest setting there is so little fluid left in the system apart from the brakes it is not worth worrying about. You will need to "bleed" the brakes until fresh fluid appears too.

There's a long running thread on the French Car Forum about harsh rides in Hydractive Xantias. All sorts of things have been suggested and tried, air in the system, LHM viscosity, regulator cut off/in pressures, etc. My XM rides much different to my Xantia and they both have the same suspension system. The only real difference I can see is that the XM is on steel wheels and different size tyres to the Xantia.

I've hydraflushed both but even after a 1000 miles of flush it's surprising how much black fluid comes out of a height corrector if you take it apart.

Steve.