Loss of lift on loader and 3 point B2601

[Loren]

Tractor info:

2015 Kubota B2601 (hydraulic trans)
LA 434 loader w/ bucket and/or forks
3rd function equipped on loader but has never been used.
3-point has a 60" rake
Hours: 170
hydraulic filters last changed in 2019 at around 60-70hrs

Hey all,
Thanks in advance for any advice y'all could offer.

Symptoms:
Symptoms started coming on gradually over a few days until neither loader nor 3 point would work.
Loss of lift to loader and 3-point.
Constantly sounds like when the loader has been maxed out. (fluid moving through pressure relief valve?)
Symptom stays the same regardless of RPMs
If I have the 3-point lever in the raised position, the 3 point will lift part way as the tractor is shut down. Cycling the tractor on and off 2-3 times will raise the 3 point fully.
Also, Loader will lift if I pull back on the control lever as the tractor shuts down.
Loader will not lower normally while tractor is running but will if the tractor is shut off. It will lower while running when put in float mode.
Loader will curl and and dump.
PTO's seem to work. They have never been used though.

Things I've done so far:
Checked fluid level (it was fine)
Checked hoses
Removed and inspected pressure relief valve. It looks fine but I suspect the spring may be worn just based on symptoms. I added a small washer to the shims and reinstalled. No improvement. I then added a second washer and at first there was no improvement but after messing around with the control lever a bit it started to function as normal. The 3 point also started working. I put it through a few cycles and it seemed fine. I thought perhaps there was some kind of blockage somewhere that cleared. I didn't want to risk over pressurizing the system so I then removed the extra washers from the pressure relief valve. The loader and 3 point continued to work normally as I lifted and lowered them a few times. The tractor sat overnight and in the morning the loader and 3-point were dead again.

I reinstalled the washers this evening and saw some improvement but it's not back to normal...

I'm confused because the washers in the pressure relief valve helped... but everything continued to work after I removed them until the tractor sat overnight.

I have ordered a gauge and coupler so I can get a pressure reading... I think its odd for that heavy duty spring in the relief valve to wear out with just 170 hours on the machine. To be fair I regularly max out the lifting capacity of the loader so that valve gets a work out.


The tractor drives fine. Forward and reverse seem normal.

I do have the WSM but I'm not a mechanic so I have a limited understanding of it.

Any advice would be very much appreciated. I tried to include all of the info I could think of. Please let me know if I missed anything

 

[Dave_eng]

Friendly advice:

It is not wise to start messing with the relief valve. In a fraction of a second you can destroy very expensive components. Especially when you do not yet have a pressure gauge.
Your symptoms point to a hose in the wrong place or a quick coupler not fully seated. Have any hoses been removed and reinstalled?

Your loader valve has a Power Beyond circuit (also called high pressure carry over or HPCO) which feeds the 3 point hitch circuit.

The two circuits (FEL and 3 pt) are intricately linked.

Relief valves will function through more cycles than you can imagine without wearing out.

Dave

 

[whitetiger]

Is the tractor plumbed for a backhoe?

 

[Loren]

Friendly advice:

It is not wise to start messing with the relief valve. In a fraction of a second you can destroy very expensive components. Especially when you do not yet have a pressure gauge.
Your symptoms point to a hose in the wrong place or a quick coupler not fully seated. Have any hoses been removed and reinstalled?

Your loader valve has a Power Beyond circuit (also called high pressure carry over or HPCO) which feeds the 3 point hitch circuit.

The two circuits (FEL and 3 pt) are intricately linked.

Relief valves will function through more cycles than you can imagine without wearing out.

Dave

Hi Dave,

Thanks for the advice. Its very much appreciated. I have a gauge on the way. I won't be tinkering with the relief valve much until I get that gauge. For the sake of being thorough I double checked all the couplers this morning... All feel and look to be tight and properly seated. Up until this problem started I had never unhooked them. I just unhooked one yesterday to make sure I was ordering the correct coupler to use with the pressure gauge. The loader has never been removed. I'm wondering if there is something wrong with the loader control valve...

 

[Loren]

Is the tractor plumbed for a backhoe?

Hi,

It does not have any rear hydraulic hook ups.

Thanks.

 

[dirtydeed]

Since you have already checked the fluid level, and don't yet have a pressure gauge I would try to relive all pressure by moving the loader valve in all directions (with tractor not running). Then disconnect and reconnect all of the loader hydraulic lines at the loader valve.

From your description, it sounds like maybe you are in relief already. Perhaps, the three point control lever adjustment is out of whack (I think its called the 3 point feedback control). Take a look in your WSM for it and how to check/adjust.

is the three point control (decent rate control knob) open? Does your 3pt hitch drop when you lower the 3 pt control stick?