Suspension Accumulator
Hard suspension? A bouncing, too high-levelled rear of the vehicle? Then the suspension accumulators (also known as pressure accumulator, pressure bomb, or bomb), are most likely worn or defective.
The suspension accumulators are diaphragm-accumulators filled with nitrogen. Their gas filling enables the dampers to compress in the first place. Over time, the gas diffuses through the diaphragm into the hydraulic oil. The accumulator spheres are filled more and more with oil. At some point there is only oil and no more gas in the accumulator. As oil is incompressible, the damper cylinders can then no longer compress. The suspension becomes hard, and the height of the rear of the vehicle can also visibly increase. Sooner or later, the dampers will start to leak, and the regulation valve may also be damaged. So basically, it is the suspension accumulators that are the actual wearing parts of the system. That’s why leaking dampers are then consequential damage. Repaired or even new spring cylinders can become leaky again very quickly if they are operated with defective or worn suspension spheres.
So in the case of repairs or the replacement of damper cylinders, the suspension accumulators should also be renewed or regenerated. At the very least, a test for existing gas pressure must be carried out. Otherwise, one will not enjoy the new or repaired levelling suspension for long. To be able to regenerate levelling suspension accumulators, a certain residual pressure must be present- the higher, the better. We do not regenerate suspension accumulators without residual pressure.
For accumulators with an oil line connection vertically into the housing, it is quite easy to check whether there is still residual pressure when the accumulator is removed. As shown below, insert a blunt object (i.e., a 3 mm Allen key) into the lower bore. If you quickly encounter a clear resistance, this is the diaphragm. This indicates that there is still gas pressure, but it is not possible to determine how much. If the tool can be inserted completely into the accumulator sphere, it is not possible to carry out a meaningful repair.
