I got stuck in the mud and used the digging arm to push myself out. The dipper quit working, no leaks, cylinder was rebuilt not long ago, linkage to control arms looked intact. Yet the dipper does not operate at all, no sound either. Any ideas? Everything else works
Sounds like it could be internal damage. You could set the boom down so the bucket is sitting on the ground, remove the hose on the base of the dipper cylinder and cap both lines, then start it up, lift the bucket off the ground so it's hanging free, and try to extend the dipper/retract the cylinder. IF it does the opposite, ie extends the cylinder/retracts the dipper, then the piston seals have failed, or the piston came off. Before doing that, you could try to heat up your hydraulic leak and find the warm spot. Use a non contact thermometer, or do it on a cool morning with lots of dew and high humidity. Start the machine up and hold the dipper stick either way for a minute, shut it off and see if you can find a warm spot on the valve or cylinder, if the weather is right, they'll start steaming with very little heat.
Thanks for the answer, there is no leak so I'm a little confused as to why I should check for one. Should I check for pressure on the lines? I don't have a gauge. I guess there could be a nut that came off inside the cylinder? Got that from a search on dipper cylinder not operating. Everything else works. Is there an easy non tool way to confirm that the cylinder is getting proper hydraulic pressure
I'm assuming the loader and other backhoe functions still work, so you have a leak somewhere. It will be an internal leak by the piston, most likely. IF it's a small leak, then you'll heat up the location of the leak by running that function. IF it's a large leak, like the piston came off the rod and the fluid is running right through the cylinder, then the whole cylinder will warm up, but slower because the all the hydraulic fluid will warm up. If the hydraulic cylinder doesn't warm up, but the valve does, then there might be a broken valve. Hydraulics are simple, you just have to think about how the cylinder works, then figure out what you're trying to determine and test that. I wouldn't bother testing pressure if the other functions work. You either have a valve issue or a cylinder issue, not that hard to determine. You probably have o ring flat face seals, so you'll need that style of caps/plugs to cap any hoses for testing purposes. If you're ordering those, you could order adapters and a pressure gauge also, but figure out what you want to do before. discounthydraulic hose is one place that sells lots of those fittings, and has a handy thread id chart too.
If the problem is as Delmer is suggesting, you won't see the leak. It's all internal. Everything looks great from the outside, but hydraulic fluid can pass right by the cylinder's piston without doing any work. Very common failure.