First let me explain the hydraulic leveling function as the fluid sees it. I apologize if this is beneath your level of understanding, but it's a basic place to start.

Since your system is full, and not leaking, we will eliminate all parts except the pump and valve.

The pump pumps fluid whenever the engine is running. The pump is capable of hundreds of PSI so if the pump is working, and has fluid, it must go one of three places.

Is fluid leaking?

Y > you have a leak, fix it.

N> > Is fluid returning to the tank?

Y> This means that either the leveling valve is not calling for lifting (adjustment), or it is leaking internally.

N> > either the rear is raising, or the pump is not working properly (fluid full?).

I suppose it is possible that the pump low-pressure line from the tank could be swollen shut and not allowing fluid to pass so the pump sucks air, but I haven't seen it yet.

If the pump is working, the fluid has to go somewhere. It goes to the valve. The valve is a simple diverter valve with three basic positions:

- If the valve lever is at the level position, it is returning all of the pumped fluid to the reservoir through the return valve and flow to the dampers/reservoirs is blocked.

- If the valve lever is at the above-level position, the valve is returning all of the pumped fluid to the reservoir, and venting the fluid from the hydraulic rams (shocks, dampers).

- If the valve lever is at the below-level position, the return to the reservoir is blocked, and the fluid from the pump is being directed into the dampers.

Since your car is not leveling, and IIRC I believe that you have posted that there is fluid returning to the reservoir (a steady stream I hope), this should eliminate all but the valve. This points to the possibility that the valve is not adjusted properly, or it is leaking internally. I believe that it has O-rings inside, which could be degraded due to the wrong fluid, contamination, or I don't know. I have been told that they are not repairable, which is of course bad.

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- Jeff