The oil eventually dripped through the pump. This afternoon I put more oil in and turned over the engine. The oil shot out the discharge end. I'm guessing that means the pump is fine. Going back to my previous post, I have to believe something is blocking the supply line. I'll pull the supply line to check for blockage. I would assume that when I remove it, I should have a clean receptacle to catch the transhydraulic fluid. It is new after all. If nothing drains out of the tractor when I remove the supply line, well, that would be another problem. Wish me luck.
OK. That's good news. The pump might be worn, but it's working.
To recap, check me on this: This is a tractor (Kubota
L225) that has had a history of normal hydraulics. Started up this year and neither the FEL nor 3pt worked. You replaced the cleanable filter in the sump, and changed the oil. Disconnecting the lines at the pump showed us that oil poured into the pump housing would sit in the pump for at least an hour and gradually trickle out the outlet. When you refilled the pump and spun the motor, the oil in the pump shot out the discharge port. Is all that right?
That only leaves a few things. One is the supply line itself could be plugged or it could have an air leak in the supply line that is above the fluid level in the sump. That leak could be in the supply line itself or in the fitting where it connects to the pump.... something like a split compression nut or split in the pipe. That's still my best guess.
Yes, if you take the supply line off the reservoir you had better be prepared for it to dump the fluid. It had better dump or else there is some other problem & very wierd. Sure you can reuse it. I've heard that some people run it through a coffee filter... does that work? But alternately you can just let it stand for a day and then carefully decant the cleared fluid for use. You don't have to be super clean. After all, that filter is probably something like 200 mesh stainless wire cloth.
What else could it be? Well, now we are getting into the unusual. I don't know how that model was plumbed, but I know it is an Open Center hydrualic system and those normally have a pressure relief valve at the loader control and also one associated with the 3pt control. If either one of those pressure relief valves is stuck in the open position - unlikely - the oil would simply circulate back to the reservoir without doing any work. But at higher RPM a pressure relief valve normally makes a sort of squealing sound when it is stuck open. Hard to miss. If the hydraulic pump is simply worn, it will still work but just not make much pressure. But even very, very worn, it would still make enough pressure to work the FEL and 3pt - even though they wouldn't be able to lift much.
An even more unlikely possibility is that the loader control valve has failed internally so that the fluid is simply diverted back to the sump by the return hose. I've never seen that.
You may want to consider puttng a "T" fitting with a small 5000 psi pressure gauge where the pressure supply feeds the loader control valve. I've got that permanently on one of my own old loaders. It doesn't tell much other than I can see the pressure in the feed line change when I work the loader. at least tells me that the pump is working.
In retrospect, I would have bet on that cleanable supply line filter you replaced as the culprit (and lost that bet). My next bet goes towards an air leak in the supply line somewhere above the level of the fluid in the reservoir.... either a wear spot in the line or a leaky connector to the pump inlet. An air leak probably wouldn't leak oil out, only air in. Even a pinhole size air leak would do it.
It's pretty easy to sit here all nice and clean and remote while you do the wrench work. Hope you find it!
rScotty
