First of all, the dealer didn't know what he was talking about. Not unusual. The E31 doesn't have the self-leveling rear suspension. Here's a diagram of the hydraulic system:
The accumulator is "5" in the above diagram, and while the diagram shows it attached to the pressure regulator, due to tight spacing it's actually located forward of the left wheel and attaches to the system via a long series of pipes. Here's a picture of the accumulator, or "bomb" with the left light assembly removed:
So, the procedure is to first turn off the engine after the car is warmed up. Depress brake pedal fully 10-15 times, or until it becomes firm at the top of it's stroke. At this point, you've expended all the stored energy in the accumulator, and the fluid reservoir should now contain the fluid that was stored in the accumulator. Another way to check if the accumulator is depressurized is to remove the cap from the reservoir and depress the brake pedal. If the fluid does not rise, the accumulator is depressurized.
Remove reservoir cover and add Pentosin CHF 7.1 until fluid level is 10mm (about 3/8") from top lip (dimension "A" below"):
With the engine running, the fluid level should drop slight to about 25mm, or about 1" below the lip.
Mark
