got JD 2510 with backhoe last yr. took BH off and found stabilizers settled. tried setting on blocks but still settle and backhoe does not so it tips. WHY DO STABILIZERS SETTLE?? NO fluid leaks out... JD dealer is so far clueless....
They leak internally where you can't see it. There's a piston inside the hydraulic cylinder that is connected to the end of the cylinder rod. Cylinders get old and eventually fluid will seep past the seal on the cylinder piston. If the cylinder is not leaking internally you won't see any fluid, but internally it is able to move - slowly - from one side of the cylinder to the other and of course that makes the cylinder rod move as well. We say it is "leaking down", but the leak is internal.
Old cylinders can droop rapidly and still work like new when the engine is running. That is because when the hydraulic system is pressurized the fluid pressure forces the cylinder seals to make a better seal with the internal surface of the cylinder. In an "open" hydraulic system, once the engine is turned off and there is no new pump pressure on the hydraulic system the hydraulic piston seals relax and the cylinders droop.
That's how an "open" hydraulic system works. Now a "closed" hydraulic system - like some John Deeres have - has an internal pressure storage tank and a one way valve so they have the ability to maintain system pressure for awhile after the engine stops running. Closed hydralic systems can maintain pressure for hours, days, or weeks......but eventually the pressure diminishes and all the hydraulic cylinders can begin to droop.
Any force that pulls on the cylinder rodl speed up that leak, and the weight of the stabilizer leg is off vertical just enough to make such a force. It's also common for bucket cylinders to leak and let the bucket droop over time.
On lots of hoes the the main boom on a backhoe is held in a retracted position by a latch of some kind, although some backhoes move the main boom over center when retracted so that the forces on the hoe actually lean back against the tractor. Either way, the boom can't move so it appears that its cylinder isn't leaking internally. You can test the main boom cylinder by leaving the main boom partly retracted overnight and see if it settles (it will).
Front end loader cylinders leak internally too. For front end loaders there is usually a spec. by the manufacturer that says how much internal leakage is allowed. It is often rated in terms of inches/hour of drop of the main loader arms.
BTW, your JD dealer may be clueless, but any of his mechanics could say what I've just said....probably better.
Enjoy,
rScotty
