How to test hydraulic pressure on rear 3ph with no loader

[haanzel]

I don't have a loader so where would I hook up a hydraulic gauge to test the pressure on a L2600? Is it the PB hose? Most have a FEL so that makes the connection easy.

 

[TheOldHokie]

I don't have a loader so where would I hook up a hydraulic gauge to test the pressure on a L2600? Is it the PB hose? Most have a FEL so that makes the connection easy.

Quick look at the parts manual shows pump connects direct to top cover. Relief is somewhere inside the cover. WSM will probably show test point and procedure. What are you trying to fix?

Dan

 

[haanzel]

Thanks, looking at the WSM, it seems the plug is next to the 3 point lowering knob.

I am trying to figure out why my 3PH is not working or weak. I replaced the large o-ring on the lift piston. It will lift at higher RPMs but appears to not be strong enough to lift an implement. Thoughts/ideas welcome.

 

[TheOldHokie]

Thanks, looking at the WSM, it seems the plug is next to the 3 point lowering knob.

I am trying to figure out why my 3PH is not working or weak. I replaced the large o-ring on the lift piston. It will lift at higher RPMs but appears to not be strong enough to lift an implement. Thoughts/ideas welcome.

Well a pressure test at that point will not be conclusive. You will certainly see low pressure but you wont know if that's due to weak pump, leaking/weak relief, and/or leaking piston seal. Does the WSM have a procedure for isolating and testing the pump?

Dan

 

[haanzel]

The pump is ok as the power steering works fine. I think the issue is somewhere between the position control valve and the lever.

 

[North Idaho Wolfman]

The pump is ok as the power steering works fine. I think the issue is somewhere between the position control valve and the lever.

There are three test ports on the block on the side of the priority valve.

Look in the WSM on the priority valve and how to check it.

Look in the WSM for the Feedback linkage and check that.

 

[TheOldHokie]

The pump is ok as the power steering works fine. I think the issue is somewhere between the position control valve and the lever.

I don't have a WSM so I am working blind. If you post the test procedures from the manual it would help.

that said hook a hose to that test port on the front of the cylinder, put the other end in the hydraulic filler, start the tractor set engine speed to 2000 RPM and raise the position control lever. If the valve and position control linkage is working you should get a solid stream of oil out of that hose.

Dan

 

[haanzel]

 

[haanzel]

Looking at the FSM, the top photo is hard to see, but it appears it's the plug I mentioned above.

The control valve has 2, one on top and one on the rear, then there is (I think) a relief valve on the side of the hydraulic lines that is on the top cover.

Dan, you are saying to put a hose on the front plug , route it to the rear filler and if there is a solid flow then it's working?

i will say I read the procedure for adjusting the lift rod and I am not certain I did it correctly, I did not hear the relief valve engage.

 

[TheOldHokie]

Looking at the FSM, the top photo is hard to see, but it appears it's the plug I mentioned above.

The control valve has 2, one on top and one on the rear, then there is (I think) a relief valve on the side of the hydraulic lines that is on the top cover.

Dan, you are saying to put a hose on the front plug , route it to the rear filler and if there is a solid flow then it's working?

i will say I read the procedure for adjusting the lift rod and I am not certain I did it correctly, I did not hear the relief valve engage.

As I said I am working blind. It's not clear where that front plug connects. If the WSM has a hydraulic schematic could you post that?

As far as my flow test it looks like you can run the hose from that test port to the orange filler right in front of it. It's going to be low pressure (50-100 PSI max) so plain vinyl tube should work. If that test point is between the control valve and pump you may get flow as soon as the tractor is started.

Dan

 

[haanzel]

Thanks Dan, your test passed with flying colors.

Which leads me to the next couple of question, why is it intermittent? Does this prove the position control valve under the seat is working?

 

[TheOldHokie]

Thanks Dan, your test passed with flying colors.

Which leads me to the next couple of question, why is it intermittent? Does this prove the position control valve under the seat is working?

I was gifted a copy of the WSM so my vision has improved - my thanks to the OTT fairy godmother

Not 100% sure but the plug appears to be in the supply line from PC valve to cylinder so the only time there is flow is when the PC valve is commanding lift. Getting flow when you raise the lever indicates the PC valve appears to be commanding lift. So why no pressure?

The WSM procedure for checking pump pressure involves a direct connection to the discharge port on the pump which is not easily accomplished and requires care since there is no pressure relief in the circuit.

You could check pressure at the outlet tube of of the PS priority flow valve. That has its own relief and with a gauge screwed into the outlet port on the PS valve should be close to 1800 PSI. If that is low it would point to the pump. If its not low then the problem would seem to be in the lift circuit of the PC valve and cylinder - e.g. pressure relief valve or o-ring.

Dan

 

[haanzel]

Thank you again Dan. I have a gauge but I need some fittings/hose to be able to check, it was setup with QA fittings when I had my tractor with FEL. Will report back.

 

[haanzel]

Finding a fitting has become a challenge. What size or type would they take? I can't seem to find a hose either, so any help would be appreciated on getting the above.

 

[TheOldHokie]

Finding a fitting has become a challenge. What size or type would they take? I can't seem to find a hose either, so any help would be appreciated on getting the above.

Where are you looking to hookbthe gauge?

Dan

 

[haanzel]

Good question, I think the easiest would be the top of the valve that the hydraulic lines run to/fro, this way there is a relief valve to safety (I think).

This one here on top. It is a 24mm socket to remove. Otherwise the next would be the one on the side, which is the bottom in the photo where the wire loom runs under.

 

[TheOldHokie]

Good question, I think the easiest would be the top of the valve that the hydraulic lines run to/fro, this way there is a relief valve to safety (I think).

This one here on top. It is a 24mm socket to remove. Otherwise the next would be the one on the side, which is the bottom in the photo where the wire loom runs under.

View attachment 109315

That valve is a priority flow divider for the PS citcuit and gets pump pressure from inside the hydraulic cover. The two hard lines are pressure out to and return from the PS unit. I suspect the hex nut is either the pressure relief or flow divider poppet. I would have to look at the parts diagram to know for sure but neither would be a test point.

Let me rephrase the question - what care you trying to learn with the test?

Dan

 

[haanzel]

The end goal is to fix my rear 3PH, it is not raising as it should. I replaced the o rings recently. Someone had mentioned pressure previously testing so that was what I was trying to do.

I think the issue is in the pressure control valve (PCV). The manual shows how to take them apart but others on here have said that they are usually replaced and not rebuilt. I understand that but then why would Kubota show how to rebuild them?

Longer story, I have a thread 6 years ago where I swapped out the FEL on the 2600 to the 2500. I swapped it successfully on the 2500 but never got this working and it's sat until recently. Started right up though! IIRC, I did swap PCVs and it did work, so that is where I am now. Although someone had mentioned there may be air in the lines, not sure how to bleed that if that is true.

Thanks for reading.

 

[TheOldHokie]

The end goal is to fix my rear 3PH, it is not raising as it should. I replaced the o rings recently. Someone had mentioned pressure previously testing so that was what I was trying to do.

I think the issue is in the pressure control valve (PCV). The manual shows how to take them apart but others on here have said that they are usually replaced and not rebuilt. I understand that but then why would Kubota show how to rebuild them?

Longer story, I have a thread 6 years ago where I swapped out the FEL on the 2600 to the 2500. I swapped it successfully on the 2500 but never got this working and it's sat until recently. Started right up though! IIRC, I did swap PCVs and it did work, so that is where I am now. Although someone had mentioned there may be air in the lines, not sure how to bleed that if that is true.

Thanks for reading.

Air bleeds itself and is not your problem. Even if you had sir in the lines the unloaded lift would still come up on a few PSI of air pressure.

Do you mean Position Control Valve (PCV) ?

First step is to try and confirm oil pressure and flow coming to the position control valve. Unfortunately the 3pt circuit on that tractor doesn't have any good test points. Like I said earlier you can test PS pressure at the flow divider to confirm the pump is making good pressure.

Dan

 

[haanzel]

Yes, sorry the position control valve.

Ok, I will try to find an adapter that will do that. Thanks Dan.