780CK hydraulics

hydraulics don't work right.. guess the pressure goes into the far side of the backhoe valve body, then halfway through there is a block that goes to the loader valve body, then at the end of the backhoe valve body, there is whats called a return valve.. somethings messed up because its trying to send all the fluid through the middle block to the loader,,, the first valve blocks (before the middle) the backhoe will function,,, maybe even the stabilizer arm seems full functioning, then the next two will move enough to pick itself off the ground but not have working power, UNLESS, you pull up on the loader bucket control,(move the bucket up) then at the same time the backhoe has more power... The control furthest to the right on the backhoe-the stabilizer,, has very little power.. gotta be sumthin messed up,, either in that middle block or the furthest return I would think. I removed a plug,, then a spring with a ball from the bottom of the center valve,, wasn't a cure,, been trying to do the same with the furthest return,, haven't got that out yet, may try again today,, or else the return is jacked up some how from the backhoe valve to the tank, the return filter in the tank was junked up pretty good,, I cleaned on it, soaked it in kerosene for a few days, then blew it out and replaced it, will get a new one if I can get the system up and goin.. thanx Steve

there is also a return in the first block of the backhoe valve body,, same block as the supply comes in. I made a post on this earlier with the symptoms,, its back,, idk, 30 posts or so. The swing on the hoe seems to be working properly, and the left stabilizer arm,, the rest are working with minimal power, and seem to make the front bucket go up when you try to use them, or you can make the front bucket go up and it gets more power to the hoe. Pulled the bottom of the last block in the backhoe valve block series,, the 'return valve' ,, pulled the cap nut, then used a bolt to get a moving piece out,,, put it back,, didn't make any change.

Had another look at the parts drawing, it is not easy to trace the circuit, the hydraulic pump put out two flows,one flow goes directly to the backhoe valve the other flow goes through the loader valve,by what you are saying the oil is escaping in the loader valve,when you use a lever you stop the oil escaping and the pressure goes to the backhoe,the most likely reason for that to happen is the O'ring that goes on the power beyond adapter (carryover adapter)has blown,you should find the adapter on the back of the loader valve connecting the line that goes to the backhoe.
AJ

thanx AJ, I was under the impression that the pressure went to the backhoe first, but maybe not,, my parts book calls the middle block in the hoe valves, a supply,, that is where the loader valves and the backhoe link. So if my problem is in the loader valve,, (I will look and see if anything there looks like power beyond) Its a multi spool valve, as its a jaw bucket,, and not so sure if someone hasn't been previously working on that as I tightened some leaking fittings. Think the backhoe has been broke so long that they welded a chain hook on the right stabilizer, lol. I might begin by checking the flow direction between the loader valves and hoe.. also I will grab my parts book and study the loader valves,. thanx again, Steve

If your loader valve is the same as what's in the parts drawing I posted take out that adapter and check the inner O'ring,if its gone hard or cracked it will let the oil bypass,the stabilizer is a different issue,it could be the check valve or the seals on the piston has failed,first sort the backhoe power,you need to check that inner O'ring.
AJ

I replaced that power beyond O ring coming out of the loader valve, didn't make any difference,, I wonder if the problem could be on the loader spool? itself, as that moves it gives power to the backhoe, or when you pull on the backhoe control,, it engages the loader

Take out the main relief valve,it is under the plug #4 in the drawing of the loader valve.
AJ