Citroen DS Sphere removal

Central to the Citroen DS hydraulic system is a set of ‘spheres’ that hold hydraulic pressure.  The spheres have an internal diaphragm so they can contain gas on one side and hydraulic fluid on the other.    One is used for each wheel to provide the suspension, as the gas forms the ‘spring’ and the amount of fluid in the sphere controls the ride height.    One is used as a place to hold a buffer of system pressure, called the accumulator, and one some cars, and additional sphere provides additional brake pressure (like another accumulator, but just for the brakes).

There are two types of spheres.   The original split type that are re-buildable, and the newer one piece type that are disposable.     You can run either type, although at least on the suspension,  the two piece type are apparently better.   Since all the accumulator is doing is providing a pressure buffer, most people use a disposable unit for this.

If you let the sphere get completely flat, the diaphragm will most likely be damaged, and the two piece spheres will need to be rebuilt (and the one piece discarded).   Therefore, it makes sense to remove the spheres every year or two and have their pressure checked and set to the correct level for the car (i.e. front and rear are different, sedans are different from wagons etc).

Citroen DS sphere removal is not particularly difficult.  To remove the suspension spheres, firstly they need to be loosened about 1/4 a turn with the suspension on high and pressurized.    This is especially important for the rear.     It is normal to use a strap wrench to do this.    It should not be particularly difficult, however on my car I found that even with a 1 metre breaker bar it was very difficult to crack the spheres.

It should not strictly be necessary, but I had to remove the air cleaner assembly to get the front sphere off.   Once the sphere have been slightly loosened then the car needs to be set to the lowest suspension setting and the system pressure released via the screw on the side of the pressure regulator.     Once this is done the spheres can be removed by hand, with something to catch the hydraulic fluid that will spill.

The spheres for the front and rear have different pressures, so it is important to make sure that the spheres are not mixed up.

I had also wanted to replace the accumulator sphere, and replace it.   My hydraulic pump needs to kick in every 5-10 seconds.   This could be because the accumulator is flat and not holding pressure.  It also could be an internal leak in one of the other hydraulic components such as the centrifugal regulator, or the steering rack.    Since my accumulator is the disposable type, and I had purchased a replacement, I wanted to change it. Citroen DS sphere removal may be easy for the suspension, but this is not the case for the accumulator.

However, despite breaking a chain wrench, I was unable to remove the accumulator.   I will likely have to remove the entire pressure regulator assembly, which is quite fiddly as all the hydraulic lines need to be removed and new seals fitted.    Something for another day.