Citroen XM Forum

He did! And only rear sphere change can most certainly make a difference but you're not there yet

Good luck with the rest of them. You'll get there!

Yeah, fully depressurised with lots of tickover on low and undoing the regulator screw (jeez, that's a handy location!). I did wonder if a membrane had gone/was going in one of the spheres. The fronts look fairly new, but I reckon the centre there could be much older too.

Yah, it's not a great place that screw. It's fine with the 2.0 petrol but I still struggle to find the screw blind as well...If you front ones are new cheap ones, they could be worse than you expect.
For some reason I think the centre ones last longer than the corner ones?

White Exec wrote: BTW, you did depressurise the system before trying to remove spheres? Makes a big difference.

An absolute must for getting the centre sphere to undo. It is the hydraulic pressure that holds them tight.

With the engine running lower the car, then open the pressure relief bolt, then switch off the engine.

Has anyone noted the alternative depressurisation in the citroen workshop manual, about 50 pumps on the brake is suggested as an alternative.

The depressurisation of the main supply circuit is not required and will actually stop depressurisation on vehicles fitted with hydractive 1 if done slightly incorrectly.
The H1 systems electrovalve needs a supply of high pressure fluid to open the Firmness regulator valves to allow pressure to escape from the centre Regulator spheres on each axle as the electrovalve does not act on them directly as it does in the H2 setup.

If you really want to release the store of pressure in the pressure regulator body and sphere do so after the ride height lever has been set to fully lowered and each wheel can be lifted by hand (with the engine runing at idle) and the engine turned off.

For H1 you need to jack the car with suspension on normal ride height and engine running, place on axle stands and crack off the two wheel spheres, then shift the lever to minimum ride height with the engine running leave for a few seconds and then turn the engine off, you should be able to lift the wheels by hand now.
Undo the wheel spheres by hand (never attampt to remove the speres on the wheel cylinders with brute force while the system is not under slight pressure as you can damage the hydraulic pipes).

Now you can undo the regulator sphere as it will contain no pressure trapped between sphere and firmness reg valve body.

Undoing the bleed on the regulator body will serve no purpose so long as you dont play about with the ride height control with the spheres off, doing this is a great way to purge the wheel cylinders and rust proof the underside of your car

D

I believe mine is H2, and I followed the process described by Dieselman. There was no way that sphere was going to shift so I thought I'd better stop before breaking something.

XMs really do make good tow cars. Though the ride goes a bit iffy when you've got a heavy trailer!

interesting trailer. I've towed a lot with my XM as well but hardly notice the weight cause my trailer is smaller and can't hold more than 400kg weight. But if you are towing 2 tons of sand there....I wish I had that blue sky..