w140 hydraulic pressure to rear self leveling suspension

[kengriffith]

on the V12 uber alles site talking about the real self leveling suspension it references the pressure in the system. My 98 s500 system has always not absorbed the road bumps very well and it seems the system is harsh in the rear. I replaced the rear accumultors but the ride did not improve much. In the DIY article it says the fluid is under a lot of pressure, but when I disconnected the lines between the strut and the accumulator, the fluid did not seem under any pressure. When I started the car to drain the system, It did flow out but not under much pressure. Just came out slowly. When I open the resevoir it is pumping back into the system but the flow is not at very high pressure. Just kind of pouring back into the resivoir. What pressure should this system be under when the car is running? Do I need to replace the tandem pump to improve the ride?