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?

 

[old grayfellow]

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?

7 hoses.
I didnt try that test yet, but I did notice that that fluid did start to come out of the tank hose (low pressure return to the transmission) when i moved the joystick to any position, which it is supposed to do according to the manuf. I also then tried removing each of the 4 channel fitting on the lines to the loader cylinders, and when I move the joystick to that respective channel, a little bit of fluid comes out, but only a low slow, flow (regardless of engine rpm) clearly not enough to actually operate the loader.
So now I have the feeling that feeling that there's actually insufficient pressure/flow reaching the valve from the tractor. Fluid does come out of the main supply hose for the controller, but maybe its not at enough pressure to actually move the loader. Going to check the supply line for power beyond and hydraulic pump supply side hoses for problems like Carey suggested, havent had time to get to that yet

 

[Harry in Ky]

Check your PM inbox.

 

[oldnslo]

When moving the joystick the only flow that should come out the tank line is return oil from the cylinders moving or system relief opening. Other possible flow path is if the power beyond plug is leaking but that usually prevents the 3 point from working properly.

 

[Anneljyrise]

There was a valve under the seat of my tractor that stopped the front loaders from working.

 

[old grayfellow]

7 hoses.
I didnt try that test yet, but I did notice that that fluid did start to come out of the tank hose (low pressure return to the transmission) when i moved the joystick to any position, which it is supposed to do according to the manuf. I also then tried removing each of the 4 channel fitting on the lines to the loader cylinders, and when I move the joystick to that respective channel, a little bit of fluid comes out, but only a low slow, flow (regardless of engine rpm) clearly not enough to actually operate the loader.
So now I have the feeling that feeling that there's actually insufficient pressure/flow reaching the valve from the tractor. Fluid does come out of the main supply hose for the controller, but maybe its not at enough pressure to actually move the loader. Going to check the supply line for power beyond and hydraulic pump supply side hoses for problems like Carey suggested, havent had time to get to that yet

After finally getting time to revisit this problem, I did as Harry suggested and got a pressure gauge, and installed it on an extra input port of the loader joystick controller (as instructed by Eric from Brand Hydraulics, the maker of the controller). Eric told me that if my hydraulic system was "closed center", I would see pressure on the gauge as soon as I started the tractor, and if it was an "open center" system, I would see pressure register on the gauge when I moved the joystick to any (non-neutral) position.
The result was that no pressure showed up either way.

However, when I raised the 3pt hitch control, the pressure on the gauge (still mounted on the joystick control valve) shot up to 2000psi and stayed there as the Yanmar relief valve (the one on the tractor itself) squealed (as always happens when the 3pt reaches top of its travel and lever is still held in the 'raise' position).

Given that the joystick controller was now getting pressure in this condition, I tried simultaneously operating the loader joystick, and then the loader moved. But as soon as I moved the 3pt lever back to neutral, the pressure to the joystick controller went to zero and of course the loader no longer operated.

So I at least confirmed that the hydraulic pump is working fine, but I'm still stumped by how the flow to the loader valve has changed like this (now requiring the 3pt to be in the raise position, where it never had to be before). I've been trying to locate a schematic map of the hydraulic system on this tractor but haven't had much luck so far. Also tried calling Hoye tractor, but Aaron is no longer there (sold the business) and the people there now didn't have any insight into my problem. They only suggested me to check the hydraulic lockout valves (which are both open), and also mentioned that "perhaps it was a line clogged somewhere". But there's only one line supplying the loader valve, which is connected to the divider block on the right rear fender. Previously there was always pressure flowing in this line whenever the engine was running, but now it apparently only reaches this line when the 3pt lever is raised.

I did manage to find this map, though it's not the most user-friendly. The path looks like the divider block circled in red (where the loader input hose is connected) is a straight shot just directly downstream of the hydraulic pump (D), while the "control valve spool" ("M", that I guess operates the hydraulic lift cylinder) is all downstream of the output block, and in fact appears to actually get all its fluid after first going through that block. So it doesn't seem to make sense that the loader valve can only work/get pressure when this (downstream) control valve spool is opened. Unless there was some kind of backflow going on.. but the diagram doesn't seem to show this would be possible..

 

[ponytug]

After finally getting time to revisit this problem, I did as Harry suggested and got a pressure gauge, and installed it on an extra input port of the loader joystick controller (as instructed by Eric from Brand Hydraulics, the maker of the controller). Eric told me that if my hydraulic system was "closed center", I would see pressure on the gauge as soon as I started the tractor, and if it was an "open center" system, I would see pressure register on the gauge when I moved the joystick to any (non-neutral) position.
The result was that no pressure showed up either way.

However, when I raised the 3pt hitch control, the pressure on the gauge (still mounted on the joystick control valve) shot up to 2000psi and stayed there as the Yanmar relief valve (the one on the tractor itself) squealed (as always happens when the 3pt reaches top of its travel and lever is still held in the 'raise' position).

Given that the joystick controller was now getting pressure in this condition, I tried simultaneously operating the loader joystick, and then the loader moved. But as soon as I moved the 3pt lever back to neutral, the pressure to the joystick controller went to zero and of course the loader no longer operated.

So I at least confirmed that the hydraulic pump is working fine, but I'm still stumped by how the flow to the loader valve has changed like this (now requiring the 3pt to be in the raise position, where it never had to be before). I've been trying to locate a schematic map of the hydraulic system on this tractor but haven't had much luck so far. Also tried calling Hoye tractor, but Aaron is no longer there (sold the business) and the people there now didn't have any insight into my problem. They only suggested me to check the hydraulic lockout valves (which are both open), and also mentioned that "perhaps it was a line clogged somewhere". But there's only one line supplying the loader valve, which is connected to the divider block on the right rear fender. Previously there was always pressure flowing in this line whenever the engine was running, but now it apparently only reaches this line when the 3pt lever is raised.View attachment 850605
I did manage to find this map, though it's not the most user-friendly. The path looks like the divider block circled in red (where the loader input hose is connected) is a straight shot just directly downstream of the hydraulic pump (D), while the "control valve spool" ("M", that I guess operates the hydraulic lift cylinder) is all downstream of the output block, and in fact appears to actually get all its fluid after first going through that block. So it doesn't seem to make sense that the loader valve can only work/get pressure when this (downstream) control valve spool is opened. Unless there was some kind of backflow going on.. but the diagram doesn't seem to show this would be possible..

The hydraulic flow "dividing" actually happens inside the 3-pt control block. So your not having power until you move the 3-pt hitch lever is consistent with your experience and the diagram.

It looks to me as if there is some issue with the 3-pt hitch valve or lever. Clog, lever misalignment or something wrong with valve mechanism itself.

The good news is you now know where to look in more detail.

All the best,

Peter

 

[Harry in Ky]

"You know where to look?" Actually no you don't, because if you did you wouldn't be here asking about it. What you need to do is take (and post) some photos of your loader valve from different angles so we can see what you see. Show us where the oil flow comes from, where it enters the loader valve, where it exits, where it goes back into the lift system, etc. Take as many as you like, there's always room for photos.

 

[old grayfellow]

Thanks guys for the input.

Here are some photos
The blue and green taped hoses are on the output side of the hydraulic joystick valve; The blue one goes to the transmission/sump, and green goes to return/input on the divider block
The hose without tape on port at the bottom of the joystick is the input, and comes there from the output port of the divider block.
One of the photos shows the hydraulic gauge attached to the second input port at the bottom of the joystick valve, and photo was taken when it was showing 2000psi due to the 3pt lever being pulled.
One more bit of info is another page from one of the manuals: a piece of info circled in red describes how you install an interior plug *inside* the divider block to block passage to the hydraulic control valve (3pt) when installing a flow meter (and also when installing a loader). This sounds relevant to the issue of interplay between the joystick controller and the 3pt controller..

 

[winston1]

I am old and slow and don't have a real good understanding of this whole thread. However, if this system worked correctly for 6 years and nothing has been changed then something must have went bad. However again, it would not be hard to check the headless plug that is spoken about. I guess it is possible that plug could have backed out. It is necessary for that plug to be installed in order for your setup to perform correctly.

 

[Harry in Ky]

My take as well. I finally got the photos large enough to read the print and concluded the internal plug inside port A must be part (or most) of the problem. That would be the next place I would look.