Loader valve query

Puriri Farm

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Equipment
B7100
Aug 17, 2019
28
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1
New Plymouth
I've got a FEL on my little B7100, it's working great. BUT, my 3 point linkage doesn't.

I pulled the cylinder head off, and all is good in there. I've inspected the 3pl valve, and it seems good as well (it's actually already been replaced by the previous owner trying to solve this same issue - so I have a spare already)

This leaves me questioning whether it's actually seeing any oil pressure at the valve.

Tracking the plumbing back, I find that the line that feeds the valve now comes off of my loader valves, right beside the line that dumps oil back into the transmission case.

So, I'm wondering whether this line is actually hooked up to the low pressure/dump side of the valve assembly, and that's why it's not moving that cylinder. BUT, I have no familiarity with the innards of that valve assembly, so I really don't know.

in this picture, the nearest left hand line goes back to the transmission. The nearest right hand line feeds the 3PL valve. On the far side of this valve assembly is a line coming from the hydraulic pump attached to the engine.

I have no idea what the C and T on the casting refer to in this context either.

Figured I'd ask here before firing it up and loosening that line to see if fluid squirts out of it..

 

North Idaho Wolfman

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It could be that there is not a power beyond fitting in the valve or the valve s not power beyond compatible.

Can you list all the information on the specific valve your using?
 

Biltit

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May 29, 2018
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Anything else attached to the pump? Original plumbing that goes back to the 3pt?

I have a 6100 with FEL i installed. I can tale pics of the plumbing if you need. I am assuming the 6100/7100 are very similar.

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Puriri Farm

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Equipment
B7100
Aug 17, 2019
28
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1
New Plymouth
I've only had the tractor a few days, so I'm working things out as I go.

It seems that the original plumbing for the 3PL was diverted to feed the loader valves.

There's a dodgy looking welded fitting on the end of the 3PL hard line which turns it into a hose and ultimately joins up as per the picture above.

There are some numbers on the plate attached to the valve - I haven't managed to figure out what they mean though.

MB-3/2S-3/18L/G-3/M
201 I00011-1

It's apparently a Youli valve - MB3, two actuators, and the rest I haven't deciphered.
Manufacturer page here
 

Puriri Farm

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Equipment
B7100
Aug 17, 2019
28
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1
New Plymouth
I've been reading a lot about hydraulic systems today, and I believe I now know why this 3PL doesn't work.

A hydraulic pump will be pumpiing fluid all the time. It normally generates flow, but not a lot of pressure. Pressure happens when the flow is restricted (diverting the fluid into a ram etc).

For this flow to happen, the system needs to be a series circuit. The fluid flows through each valve assembly in series, and then dumps back to the reservoir to be recirculated.

The current configuration of my system (assuming that those two near side hoses are coming off the same manifold) means that we have a parallel section in our circuit, which will not work. The 3PL will see minimal flow when 'off', and when engaged, will cause all of the flow to go through the other hose directly to the reservoir.

If this is the case, I need to eliminate the hose that dumps directly from the loader valves to the reservoir, and push all of the flow through the 3PL valve assembly, as it would have been pre-loader modifications. Should be easy enough to find a couple of blanking plugs and just remove that parallel fluid path. This 3PL may not have worked at all since the loader was installed.
 

Dave_eng

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M7040, Nuffield 465
Oct 6, 2012
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Williamstown Ontario Canada
The C is likely for "High Pressure Carry Over," a common term used instead of power beyond.

For that feature to work the valve body would have required a special sleeve or plug installed in the valve body. It is possible the original installer of the valve did not install the sleeve or plug.

Suggest you email YOULI-America at the email on this web page:

http://www.youli-america.com/

Ask if they can provide the instructions for adding High pressure Carry Over on the valve you have. Armed with that info you can check if the sleeve or plug is present.

Your plan to divert the tank hose to the 3 pt hitch is unwise. Typically a valve's tank port will not be designed to tolerate the full system pressure which is what will happen when the 3 pt is raised. Tank ports are normally rated for 500 psi which is why power beyond exists. The MB-3 valve is only rated for 360 psi on the T port.

As a general caution, using plumbing fittings for hydraulic work is unsafe as those fittings are not designed for the pressures which can occur in the system.

Dave
 

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Biltit

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May 29, 2018
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Do you have a diverter valve under the front of the seat?

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North Idaho Wolfman

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Pull off the line and fitting that goes to C (PB) look inside for a HEX plug, if it's not there then that's your problem.

 

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Puriri Farm

New member

Equipment
B7100
Aug 17, 2019
28
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1
New Plymouth
Dave-eng - that same thought about back pressure limits occured to me in the middle of the night. I still haven't resolved how this system can work at all with that second path to dump in place though.

Wolfman, I pulled those fittings, and can see a hex in there. given the brilliant schematic you provided, I don't see how a plug there would actually help my cause any though - so I'm just going to bow to your greater experience with these things..

Just for the sake of interest, I messed around wrenching on things a bit.

Without changing anything, and with the tractor at idle, and the FEL disconnected, I can load up the pump by pulling the loader levers. This tells me there's sufficient pressure at idle to try and do something, and also gives me an audio cue that there's work being attempted.

So, I messed with the 3PL lever, and got nothing. The diverter valve on the 3PL cylinder head is in the 3PL position (great thought biltit - I'd messed with that already though). So, risking bodily harm, disfigurement, and potentially great pain, I threw a heavy rag over the hydraulic line where it connects to the 3PL, and loosened the nut. Heard nothing, so had a look, and it was dripping without any real enthusiasm. Backed it right out, and there's no flow there. For the sake of completeness, I undid the other end of the line as well, where it's plugged into the FEL valves, and same story there.

So, 3PL is seeing no fluid, well, at least not enough to do anything useful with.

Next question: does the 3PL actually work? I took one of the FEL quick releases off, and swapped it with the 3PL feed. Pulled the FEL lever back to send fluid down the line, and yes, the 3PL actuator works perfectly as expected, and the arms come up.

Milliseconds later I was reminded that I only had the cylinder head half bolted on, and got a shot of hydraulic fluid to the leg of my jeans. That'll wash right out, so no worries! (and is exactly why I was only running at idle.. just in case!)

So, in summary:
- My 3PL works perfectly given fluid
- The current set up isn't giving it fluid
- The hex cap screw / PB plug is in place inside the FEL valve assembly
 

Puriri Farm

New member

Equipment
B7100
Aug 17, 2019
28
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1
New Plymouth
Imagining for a minute that this FEL valve can't handle the 3PL back pressure in any configuration.. what would happen if I swapped the sequence, and put the FEL valves AFTER the 3PL?

I could use the 3PL diverter valve (that you'd usually use to run a tip trailer / splitter / whatever other accessory), and plumb that into the FEL input side. The existing dump line from the FEL would stay in place.

This would in theory work, BUT, means a bit of messing about with additional hydraulic lines etc, and assumes that the 3PL valve assembly is okay with the back pressure from the FEL.

I'll email youli and see what they say about whether it's possible to run the 3PL downstream of their valve block or not.
 

Puriri Farm

New member

Equipment
B7100
Aug 17, 2019
28
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1
New Plymouth
Actually... just re-reading dave-eng's earlier post.

If 'C' is for high pressure carryover, and 'T' is the tank port.. is my problem simply that I have inherited a machine with the 3PL plumbed into the tank port, and the High Pressure carryover port plumbed into the tank?

Could it be that simple?
 

Biltit

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May 29, 2018
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Trace it out and see, could be i suppose.

I plumbed mine into the diverter valve, that was how kubota recommended it. It does mean you can only use the FEL or the 3pt seperately though.

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Puriri Farm

New member

Equipment
B7100
Aug 17, 2019
28
0
1
New Plymouth
Yeah, that's definitely the way mine is plumbed currently. Once I get the new bolts for this cylinder head, I'll swap the C and T hoses around and see if it magically starts working!

Fingers crossed that's all it was.

Trace it out and see, could be i suppose.

I plumbed mine into the diverter valve, that was how kubota recommended it. It does mean you can only use the FEL or the 3pt seperately though.

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Puriri Farm

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Equipment
B7100
Aug 17, 2019
28
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1
New Plymouth
Well.. I sure went about that all the long way!

I swapped the tank and 3PL lines to the opposite outputs on the FEL valve block, and now the 3PL works.

If that little hex plug in the output means that it can handle the back pressure from the 3PL, then I'm all done with this particular headache.

Thanks for all the help guys - I have way more understanding of tractor hydraulics now than I did when I first asked, and that's mainly thanks to your collected wisdom.
 

Dave_eng

Well-known member
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Equipment
M7040, Nuffield 465
Oct 6, 2012
5,108
926
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Williamstown Ontario Canada
Well.. I sure went about that all the long way!

I swapped the tank and 3PL lines to the opposite outputs on the FEL valve block, and now the 3PL works.

If that little hex plug in the output means that it can handle the back pressure from the 3PL, then I'm all done with this particular headache.

Thanks for all the help guys - I have way more understanding of tractor hydraulics now than I did when I first asked, and that's mainly thanks to your collected wisdom.
Appreciate you providing the final chapter. it helps us all learn.
Dave
 

North Idaho Wolfman

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L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
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If that little hex plug in the output means that it can handle the back pressure from the 3PL, then I'm all done with this particular headache.
The hex plug (power beyond plug) makes the valve a power beyond valve, otherwise the Carry over (power beyond port) and the Tank (return) port are connected.

So yes in closing you're good to go, now go get some work done.