Hydraulic problem.. I'm stumped

[old grayfellow]

I've got a Koyker 80 loader on my YM186D, and have been using the loader for at least 6yr with no problems.

Recently had a fluid leak on one of the loader hose connectors on the power beyond block (at rear of tractor near seat), and the hydraulic fluid got low, loader was a bit sluggish/jerky.
Tightened both those connectors, topped up fluid (303 type), and now all of a sudden the loader does not work AT ALL. Absolutely no response to movement of the loader controller joystick to any position.

Took off the supply hose at the loader control valve inlet and confirmed plenty of fluid was flowing out of it when tractor was running. Took off one of the loader bucket hoses at the cylinder, activated those cylinders with joystick, no fluid coming out at all.
The 3pt hitch works fine. Lifts the tiller quickly, and makes the pressure relief valve squeal if I hold the lever in up position after it reaches the top.
So these things indicate the tractor's hydraulic pump is working fine, and fluid is getting to the loader control valve, so I focused on that valve.

Carefully loosened the return line from controller back to the power beyond with tractor running, and fluid is flowing out around the threads as I loosen.
Talked to Brand Hydraulics (manuf. of the control valve) and they suggested the pressure relief valve on the controller might be stuck open, thus preventing pressure in the controller needed for working the loader. But I tried loosening & removing the outflow hose from the relief bypass leading back to the transmission, and no fluid was coming out of it with tractor running (inside of coupling was even dry, looked like it had never seen fluid). This indicates that the pressure relief valve on the loader controller body is not stuck open.

Doesn't seem possible that problem could be caused by internal leakage past the spools due to wear-- the problem happened all at once, black and white. Loader had been working fine and strong prior to this problem.

So I'm stumped...

 

[ponytug]

That sounds like you have a blown o-ring in the valve, or debris in the valve, or in the hose to the cylinder, and if it were me, I would bet on the valve body/o-ring.

The repair involves disassembly of things that need to be "heart surgery" clean (scrub, pressure wash, blast with compressed and then brake cleaner and more compressed air before starting until it looks brand new) before starting the disassembly and then clean the threads after the first couple of turns with compressed air and brake cleaner. Then see what you find, cleaning it out with brake cleaner carefully as you go.

Or take the valve off and bring it to your local hydraulic shop.

Good luck,

Peter

 

[dodge man]

I know on a lot of tractors when people have a sudden problem like that they have a quick connect that isn’t seated well. I’m just guessing you don’t have quick connects but is there another connection that could be causing this? Is one of the connections that was leaking the problem? There isn’t another valve in the system stuck is there, like for a rear remote?

 

[old grayfellow]

That sounds like you have a blown o-ring in the valve, or debris in the valve, or in the hose to the cylinder, and if it were me, I would bet on the valve body/o-ring.

The repair involves disassembly of things that need to be "heart surgery" clean (scrub, pressure wash, blast with compressed and then brake cleaner and more compressed air before starting until it looks brand new) before starting the disassembly and then clean the threads after the first couple of turns with compressed air and brake cleaner. Then see what you find, cleaning it out with brake cleaner carefully as you go.

Or take the valve off and bring it to your local hydraulic shop.

Good luck,

Peter

Hi Peter

 

[careyo63]

Check you lines to the suction side to the pump. Just had the same problem. Loader was Jeky and slow. Pulled apart checked the strainer basket and cleaned. Double Chk. the filters. Mine was dirty and the same thing happened. Made it worse. I had to pull it back down and luck have it I double checked the strainer and it was clean. I just so happen to look inside the Hyd. line and it bubbled up inside. The inside hose line was swelled up and almost pinched shut. Replaced it and now it's super smooth. I'm thinking after I cleaned the basket the suction was so much higher it pretty much pinched the hose shut inside. NAPA had the hose 20$. Make sure the pin Hyd. pump is good and you are moving fluid.

 

[old grayfellow]

Hi Peter, Thanks for your reply,

The spools in the controller don't have O-rings, they're just a close-tolerance metal-to-metal fit. There is an O-ring(s) in the pressure relief valve assembly (according to the manufacturer) but seems like the fact that there's no fluid coming out of the relief valve hose pretty much proves that any potentially bad o-ring leaking in there is not the problem.
While debris blocking one of the ports for the loader hoses could be a possibility, it seems very unlikely that all 4 of the ports/hoses could have have gotten blocked simultaneously (since none of the 4 loader functions work eveen a little bit). It's almost as if there's no/insufficient pressure to the input of the controller, this would explain why none of the 4 channels work. I do know there's flow of fluid, but I don't have a gauge to measure actual pressure. But since there's only one hydraulic pump on the tractor and it has plenty of pressure to trigger (squeal) the 3pt relief valve, I assume there must also be enough pressure to operate the loader.

I definitely hear you about the demanding nature of cleanliness, that's why I really don't want to take this thing apart if I don't have to. Unfortunately our local hydraulic shop can't do this kind of work any more, and I'd have to send it out.

 

[old grayfellow]

I know on a lot of tractors when people have a sudden problem like that they have a quick connect that isn’t seated well. I’m just guessing you don’t have quick connects but is there another connection that could be causing this? Is one of the connections that was leaking the problem? There isn’t another valve in the system stuck is there, like for a rear remote?

I do have quick connects, that was the first thing I checked. Also verified they were not the problem by unscrewing the fittings they were attached to while leaving them connected together, and fluid did flow through them.
There is a valve that can be shut off to block flow to the power beyond, but I didn't mess with that (and it was working before). Plus, the fact that fluid is flowing through the loader controller proves nothing upstream of it is shut off.

Guess I should check for flow out of the downstream end of power beyond (rear remote) return hose also though.

 

[ponytug]

Granted, I don't know your valve, but if your pump is working, and you are getting flow into the valve, but not out, then it has to be diverting in the valve. I would take it apart and look for a chunk of something. I had something similar happen on my FEL valve. I took it apart, couldn't find anything, and put it back together and it has run just fine for another ten years. My service expert thought it was a tiny piece of debris that washed out in the oil as I did the disassembly.

Since you have a power beyond, I would guess that the valve is diverting the flow there for some reason.

This isn't like rebuilding a transmission or an injector pump, you just need to keep things clean.

All the best,

Peter

 

[oldnslo]

I've got a Koyker 80 loader on my YM186D, and have been using the loader for at least 6yr with no problems.

Recently had a fluid leak on one of the loader hose connectors on the power beyond block (at rear of tractor near seat), and the hydraulic fluid got low, loader was a bit sluggish/jerky.
Tightened both those connectors, topped up fluid (303 type), and now all of a sudden the loader does not work AT ALL. Absolutely no response to movement of the loader controller joystick to any position.

Took off the supply hose at the loader control valve inlet and confirmed plenty of fluid was flowing out of it when tractor was running. Took off one of the loader bucket hoses at the cylinder, activated those cylinders with joystick, no fluid coming out at all.
The 3pt hitch works fine. Lifts the tiller quickly, and makes the pressure relief valve squeal if I hold the lever in up position after it reaches the top.
So these things indicate the tractor's hydraulic pump is working fine, and fluid is getting to the loader control valve, so I focused on that valve.

Carefully loosened the return line from controller back to the power beyond with tractor running, and fluid is flowing out around the threads as I loosen.
Talked to Brand Hydraulics (manuf. of the control valve) and they suggested the pressure relief valve on the controller might be stuck open, thus preventing pressure in the controller needed for working the loader. But I tried loosening & removing the outflow hose from the relief bypass leading back to the transmission, and no fluid was coming out of it with tractor running (inside of coupling was even dry, looked like it had never seen fluid). This indicates that the pressure relief valve on the loader controller body is not stuck open.

Doesn't seem possible that problem could be caused by internal leakage past the spools due to wear-- the problem happened all at once, black and white. Loader had been working fine and strong prior to this problem.

So I'm stumped...

Old fellow
How many hoses are connected to the loader valve? 6 or 7

From your description there should be 7.
Pressure in
Power beyond
Tank
2 for loader
2 for bucket

is this correct?

When you shift one of spools in the loader valve does oil still come out the power beyond port on that valve?

 

[winston1]

You don't possibly have your power beyond and tank hoses switched?