Depressurising - Alternative methods?

[BrendanM]

I want to remove the rear spheres from a 1997 XM estate which uses the Hydractive 2 system. It is not roadworthy and the engine has not run for over 2 years.

The standard procedure is to depressurise with the engine running but that might not be so easy now.

Is there an alternative way of doing it?

[Peter.N.]

The only way I have ever depressurised mine is by setting the suspension to its lowest point and leaving for for a few minutes. You can never completely depressurise the rear as the hydractive system maintains some, once you have cracked the joint undo it a turn or two and leave it to bleed out for a few minutes.

Peter

[xmexclusive]

The only things that provides resistance when undoing rear spheres is the pressure and the hydraulic pipe.
Pressure is therefore best left on to crack the spheres.
Then unscrew the last one just enough to let the pressure leak off.

John

[BrendanM]

I bought a £15 sphere removal tool through ebay.
It fitted the suspension spheres which have the Citroen symbol but it would not fit around the middle of the central sphere. I tightened up the screw off centre and it turned it.

Is the rear central sphere a different size normally? Or could this be a sphere from another manufacturer?

What I would like to know is the range of different circumferences of spheres that I might encounter on an XM.

Many thanks for your help so far.

Brendan

[xmexclusive]

Hi Brendan

In practice there are small variations in XM sphere diameters.
Not something that Citroen applied a tight tolerance to.
So type and manufacturer variation can occasionally be too big for the steel band tools.
For these I use a chain or nylon strap wrench.
Some spheres on my XM's cannot be got to using the steel band tool.
No room to use the handle.

John

[noz]

My sphere removal tool must be 20 years old at least. I bought it from Pleiades when I ran CXs every day and it fitted the larger spheres perfectly. However, when I started to run XMs I found that occasionally the tool would slip and I'd need to slip a shim underneath the band to make it grip. As time went on the slipping got worse. On the face of it the spheres definitely looked like they were getting smaller although I never actually measured them to find out.

Eventually I got so fed up with using shims I ran three small welds down the inside face of the band equidistant around the circumference. Initially the welds were too large and I had to file them down. It now works a treat. My guess is that the band was being slowly stretched every time I used it.

Cheers

noz

[noz]

Sorry Brendan, I should have answered your question first. The official Citroen method of depressurising with no engine is to run the hydraulic pump using an alternative drive. I've used an electric drill in the past with the drive belt hooked around the chuck. Alternatively remove the spark plugs or injectors as appropriate and simply crank the engine to turn the pump.

Once you can turn the pump set the suspension to the lowest setting and continue to rotate the pump until you hear the regulator reach its set point and turn off. Keep turning until the car sits down on all fours. You'll need to power up the suspension ecu with a battery to open the electrovalves. Stop pumping and release the remaining pressure by undoing the release screw on the regulator.

The alternative options offered above will work but you need to be aware of what you're doing. When a normal compression joint is slackened the resulting tiny gap in the seat allows pressure to escape in a controlled manner. It's easy to tell when it's empty.

The Citroen pipe or sphere sealing method does not work like that. The rubber seal self-seals against the annular space within which it is contained. As long as the rubber seal is contained it will continue to hold pressure. This means that the seal will hold pressure all the time you are slackening the tubing nut or sphere. With nothing leaking out you will be tempted to believe there is no pressure. However at a certain point in the slackening process the seal will suddenly let go. Never undo the tubing nut or sphere completely until you are absolutely sure there is no pressure left.

Please wear safety goggles when you do this. I never do any work on hydraulic without glasses or goggles after a couple of near misses many years ago when I was doing exactly what you are about to do.

Hope that helps.

Cheers

noz

[citroenxm]

you can quite tell if a sphere has pressure behind it..

Once the initial "Crack Undone" bit has been done and the sphere has been turned ONE full turn, if the sphere is no lighter then finger grip lightly to undo. If you still need to grip the spheres heavyily to undo it theres pressure, but turn it slowly and slowly, eventually the pressure will push the seal out and it should gush away then releaving the sphere. This problem tends to occur MORE on later cars with Anti Sink Valves on them as they shut off when the system pressure drops under a certain bar, this locking the struts out... unless properly presure relased they will hold.

Earlyer "Sinker" cars dont hold pressure EVEN if the regulator is still closed, the car once sat for a few hours will have NO pressure in the legs.

Anti Sink was not added untill S2 cars, and around 1996 ..