Originally Posted by PMSPKS
I am going to check for leaks as suggested. I don't consider it a real problem as it only happens when parked in storage for a period. The jack retracts as soon as I fire up the engine.
I don't see where you mention what brand leveler system you have.
My experience is with Lippert LCI hydraulic leveling system.
However, I do have industrial experience in hydraulic systems.
When the jacks are retracted, and up fully, system shuts down and there should be no pressure present, as they do not incorporate accumulators in the system.
To me, it could be one of a couple things, unless it is physically leaking fluid to a puddle on the ground (that obviously can be traced).
With Lippert system;
Each jack has a 2-way holding valve, either it is sticking, or it is partially manually held open by its set screw as someone mentioned.
Sticking ones need replaced.
To deploy, or retract a cylinder, the fluid must pass through this solenoid controlled logic valve.
When it is shut, no fluid should pass (2 way: open or closed).
The directional valve determines the direction of flow, to deploy, or retract.
The other possibility is within the jack cylinder itself.
The piston seals could be leaking by, allowing the fluid to get onto the other side of the piston, while gravity acts on the ram (rod shaft).
I cannot say for sure, if they are lip type seals, one way leaking is possible, especially if they are stacked back to back (normal & correctly installed).
I have never taken one apart to see what is in there, but if the seals were o-ring type, then internal leak by is possible in both directions.
I would think that if this were the case, you might experience leak by while the weight of the camper is on it, then just as slowly, you would lose your level.
I doubt if they are 0-ring type, but you never know.