Trouble Shooting FEL B2601

[B2601WH]

B2601

2015 B2601
FEL & Back Hoe
10,000 hours of operations
Scheduled PM’s performed religiously
Machine has been USED, moving well over 300 tons of rock, sand, dirt, cement, landscape blocks

SYMPTOMS
Started experiencing issues with FEL a couple months ago. Will not lift load of anything. It will go up just fine without a load, Will not go DOWN unless in float or I shut the machine off. Now the 3 point WILL NOT LIFT at all. You can move it up and down by hand freely.
It will HOLD full bucket of cement
Will curl and dump just fine
Will lift front of machine, IE: to change tire or drain oil
Backhoe functions just fine
Drive and reverse work great
Front and middle PTO work

TROUBLE SHOOTING STEPS TO DATE
Tested with different levels of Hydraulic fluid, no change
Replaced Hydraulic fluid/filters, not change
Checked 3-point control speed knob (OPEN), no change
Cranked steering wheel left and right, no change
Disconnected Backhoe, no change
Replaced all FEL quick connections, no change
Drained/flushed all FEL lines and connections, no change
Removed FEL valve from tractor disassemble/visually inspected (no scaring, pitting, seals looked good) Flushed unit with Diesel fuel, blew out with compressed air, no change
Flushed all Hydraulic pipes, no change
Tested pressure HAVE ONLY 1300-1500lbs of pressure
Replaced Hydraulic pump, no change in pressure, lift/lowering of FEL or 3-point lift

According to Kubota WSM you can adjust the 3-point Hitch Relief Valve or as everyone else calls it the Pressure Relief Valve with shims

When I remove the Hydraulic Valve Assembly to clean/inspect my pressure relief plug/bolt didn’t have 2 of the #3 plain washers, page 7-S8

Before purchasing a $1000 bolt & spring (Messicks part #YW239-95100) (Pressure Relief Valve / 3-point Hitch Relief Valve) I need a 2nd, 3rd, and 4th etc… set of eyes to know this is my next step. Or should I just try 2 washers??

 

[TheOldHokie]

B2601

2015 B2601
FEL & Back Hoe
10,000 hours of operations
Scheduled PM’s performed religiously
Machine has been USED, moving well over 300 tons of rock, sand, dirt, cement, landscape blocks

SYMPTOMS
Started experiencing issues with FEL a couple months ago. Will not lift load of anything. It will go up just fine without a load, Will not go DOWN unless in float or I shut the machine off. Now the 3 point WILL NOT LIFT at all. You can move it up and down by hand freely.
It will HOLD full bucket of cement
Will curl and dump just fine
Will lift front of machine, IE: to change tire or drain oil
Backhoe functions just fine
Drive and reverse work great
Front and middle PTO work

TROUBLE SHOOTING STEPS TO DATE
Tested with different levels of Hydraulic fluid, no change
Replaced Hydraulic fluid/filters, not change
Checked 3-point control speed knob (OPEN), no change
Cranked steering wheel left and right, no change
Disconnected Backhoe, no change
Replaced all FEL quick connections, no change
Drained/flushed all FEL lines and connections, no change
Removed FEL valve from tractor disassemble/visually inspected (no scaring, pitting, seals looked good) Flushed unit with Diesel fuel, blew out with compressed air, no change
Flushed all Hydraulic pipes, no change
Tested pressure HAVE ONLY 1300-1500lbs of pressure
Replaced Hydraulic pump, no change in pressure, lift/lowering of FEL or 3-point lift

According to Kubota WSM you can adjust the 3-point Hitch Relief Valve or as everyone else calls it the Pressure Relief Valve with shims

When I remove the Hydraulic Valve Assembly to clean/inspect my pressure relief plug/bolt didn’t have 2 of the #3 plain washers, page 7-S8

Before purchasing a $1000 bolt & spring (Messicks part #YW239-95100) (Pressure Relief Valve / 3-point Hitch Relief Valve) I need a 2nd, 3rd, and 4th etc… set of eyes to know this is my next step. Or should I just try 2 washers??

You need to stop the blindfolded shotgun attack and focus on finding the problem.

Let's start with pressure. That is more than enough to operate the hydraulics on the tractor. How and where did you test pressure?

Dan

 

[B2601WH]

You need to stop the blindfolded shotgun attack and focus on finding the problem.

Let's start with pressure. That is more than enough to operate the hydraulics on the tractor. How and where did you test pressure?

Dan

Thank you for your response Dan!

Started the trouble shooting process with the easy stuff and systematically kept advancing.
Didn't learn about the pressure issue until I purchased the gauge.

I tested the pressure on the top and bottom (white and yellow) FEL quick connectors.

 

[TheOldHokie]

Thank you for your response Dan!

Started the trouble shooting process with the easy stuff and systematically kept advancing.
Didn't learn about the pressure issue until I purchased the gauge.

I tested the pressure on the top and bottom (white and yellow) FEL quick connectors.

OK - thats a reasonable starting point. Now what is the problem with the front loader operation? With that sort of pressure it should raise a substantial load.

Dan

 

[B2601WH]

OK - thats a reasonable starting point. Now what is the problem with the front loader operation? With that sort of pressure it should raise a substantial load.

Dan

The front loader will not lift any amount of dirt, sand, rock, gravel cement... The bucket will raise, but only when empty. I believe the max pressure on a LA434 is 2000lbs. I don't know what the output was when I purchased the B2601. I'm assuming it was more since the FEL won't lift anything but its self.

 

[TheOldHokie]

The front loader will not lift any amount of dirt, sand, rock, gravel cement... The bucket will raise, but only when empty. I believe the max pressure on a LA434 is 2000lbs. I don't know what the output was when I purchased the B2601. I'm assuming it was more since the FEL won't lift anything but its self.

Yes, the work port pressure is low and since you replaced the pump I think we can safely assume it is not the problem. Unless the relief valve poppet, spring, or the seat in the valve is damaged you don't need new parts - just more spring tension. You do that by adding shims - I would not use plain washers. Kubota does not sell them for that valve but you should be able to find something that will work at McMaster.

What is bothering me is that valve sets the max pressure for the rest of the system and everything else seems to work OK at that pressure. I think I would test pressure at the backhoe outlet before spending a lot of time, effort, or money on anything in that valve.

EDIT: I did some more thinking - dangerous territory.

Your pressure is low but the only thing that seems to be not working is the lift side of the boom cylinders. If I understand your symptoms you can lift the front of the tractor using the other side of the boom cylinder and the backhoe and 3pt both lift and dig OK. That suggests that one or both lift cylinders may be bypassing on extend. You can test that by putting the pressure gauge in a tee on the lift side port and reading pressure with the cylinders connected. If you are not getting that 1300-1500 PSI the cylinder is bypassing.

The Kubota price for that relief valve assembly is insane. I would buy a whole new valve at that price which may be exactly what they have in mind.

Dan

 

[B2601WH]

Yes, the work port pressure is low and since you replaced the pump I think we can safely assume it is not the problem. Unless the relief valve poppet, spring, or the seat in the valve is damaged you don't need new parts - just more spring tension. You do that by adding shims - I would not use plain washers. Kubota does not sell them for that valve but you should be able to find something that will work at McMaster.

What is bothering me is that valve sets the max pressure for the rest of the system and everything else seems to work OK at that pressure. I think I would test pressure at the backhoe outlet before spending a lot of time, effort, or money on anything in that valve.

EDIT: I did some more thinking - dangerous territory.

Your pressure is low but the only thing that seems to be not working is the lift side of the boom cylinders. If I understand your symptoms you can lift the front of the tractor using the other side of the boom cylinder and the backhoe and 3pt both lift and dig OK. That suggests that one or both lift cylinders may be bypassing on extend. You can test that by putting the pressure gauge in a tee on the lift side port and reading pressure with the cylinders connected. If you are not getting that 1300-1500 PSI the cylinder is bypassing.

The Kubota price for that relief valve assembly is insane. I would buy a whole new valve at that price which may be exactly what they have in mind.

Dan

Thanks for the great analysis!

Will pressure test at backhoe
Will try the tee on lift side port

Symptoms:

3 point hitch IS NOT functioning, will not lift. can manually lift by hand without resistance.

 

[dirtydeed]

I really don't think that you are supposed to dead head the power beyond circuit by testing at the backhoe. That hydraulic loop always needs to be closed.

Your pressures are definitely low. Fix that first by adding the arbor shims (here is a link on amazon).

https://www.amazon.com/Kubota-Increase-Hydraulic-Pressure-Adjustment/dp/B08HM8M9LG?th=1

You can also get the shims directly from Kubota. I believe each 0.1 mm will raise your pressure approx 40 PSI. I got my shims from BXpanded for free with their pressure test kit.

from my notes:
Kubota: SHIM 0.4, Part # 31351-37950 Messicks part number

[HST Model (With Front Loader Valve)]
• Thickness of shims (4)
0.10 mm (0.0039 in.)
0.20 mm (0.0079 in.)
0.40 mm (0.016 in.)
0.60 mm (0.024 in.)

1351-37970 110 SHIM 0.10mm
31351-37960 110 SHIM 0.20mm
31351-37950 110 SHIM 0.40mm

dia (#10 stainless). factory had three shims of different thickness's ,used metric measurements on my dial caliper because I read somewhere that 1mm = 40 psi.
The diameter of the shims is 12 mm, some have holes in them and some don't

You can download the WSM for free here: https://www.kubotabooks.com/AutoIndex/index.php?search=B2601&dir=&searchMode=f

 

[TheOldHokie]

Thanks for the great analysis!

Will pressure test at backhoe
Will try the tee on lift side port

Symptoms:

3 point hitch IS NOT functioning, will not lift. can manually lift by hand without resistance.

That changes the calculus and now we do need a pressure test at the backhoe hookup. You should see the exact same pressure there that your see at the loader work ports.

If you have pressure there then move your test point to the back hoe return hose coupler. You should have the same pressure there.

If you don't have pressure all the way through there is a blockage somewhere.

Dan

 

[TheOldHokie]

I really don't think that you are supposed to dead head the power beyond circuit by testing at the backhoe. That hydraulic loop always needs to be closed.

You would be mistaken. The main pressure relief is still in the circuit and its no different than dead heading at the loader valve work ports. The main system relief (which on this tractor is in the loader valve) will open at it's set pressure which seems to be 1300-1500 PSI and everybody is happy as a clam. Same goes for pressure testing at the return side of the backhoe. This is how you step along the system isolating the individual pieces so you can identify the one that is not operating correctly.

When you are pressure testing an open center system you just have to be sure there is a relief somewhere upstreaam of the gauge and it is opening. When you have the gauge teed into the circuit like I described for the lift circuit you are measuring operational pressure at the moving actuator not stalled releif pressure but its still the same concept. Thats why you read the schematic and identfy your test points based on the location and order of the individual devices. As you can see item number 17 is the main pressure relief and will protect the pump when you block open center flow at the backhoe.

Dan

 

[dirtydeed]

You would be mistaken.

Dan

I get what you're saying that it should go into relief. However, Kubota specifically states to never start the tractor with the hose loop disconnected.

 

[TheOldHokie]

I get what you're saying that it should go into relief. However, Kubota specifically states to never start the tractor with the hose loop disconnected.

I kniow what Kubota states. They are talking to operators that have little if any undersatnding of the hydraulic system and might run the system for days like that. They are not talking about controlled pressure tests conducted by someone that understands what they are doing.

Dan

 

[dirtydeed]

I kniow what Kubota states. They are talking to operators that have little if any undersatnding of the hydraulic system and might run the system for days like that. They are not talking about controlled pressure tests conducted by someone that understands what they are doing.

Dan

That makes sense.

 

[B2601WH]

Hydraulic "GURU'S"

Thank you for the crash course on Hydraulic troubleshooting!

Will forge forward with testing at the backend in the am

 

[lugbolt]

check the feedback link on the 3ph

 

[TheOldHokie]

Thanks for the great analysis!

Will pressure test at backhoe
Will try the tee on lift side port

Symptoms:

3 point hitch IS NOT functioning, will not lift. can manually lift by hand without resistance.

I should have asked this earlier. You have the backhoe off the tractor. Did you loop the side supply and return lines together after you removed it?

Dan

 

[B2601WH]

I'll try to recap chronologically

Shims ordered
Installed .7mm/273lbs

Tested FEL, will lift SMALL amount of weight. When pushing stick forward to go down, bucket will start to Raise for micro second and then stop. Still no down on FEL unless in FLOAT.

Pressure tested FEL top and bottom ports both at 1500lbs
Pressure tested backhoe supply 1500lbs
NO PRESSURE on the return, according to the gauge.
However backhoe works fine?

Have not adjusted feedback linkage on 3ph? ASSUMED this was either hydraulic hose, fitting, pump, valve blockage issue

When Troubleshooting FEL, didn't physically remove hoe, I keep it on for weight.

Next steps:

Loop backhoe as suggested and re-test FEL ports?

 

[TheOldHokie]

I'll try to recap chronologically

Shims ordered
Installed .7mm/273lbs

Tested FEL, will lift SMALL amount of weight. When pushing stick forward to go down, bucket will start to Raise for micro second and then stop. Still no down on FEL unless in FLOAT.

Pressure tested FEL top and bottom ports both at 1500lbs
Pressure tested backhoe supply 1500lbs
NO PRESSURE on the return, according to the gauge.
However backhoe works fine?

Have not adjusted feedback linkage on 3ph? ASSUMED this was either hydraulic hose, fitting, pump, valve blockage issue

When Troubleshooting FEL, didn't physically remove hoe, I keep it on for weight.

Next steps:

Loop backhoe as suggested and re-test FEL ports?

You have got me totally confused as to how the tractor is configured.
Please answer the following one by one.

1. Is this a BH70 backhoe? If not what is it?
2. Is the backhoe mounted or not?
3. If it is mounted how are the 3pt arms still on the tractor?
4. If it is mounted is it connected to all three hydraulic outlets?

Now back to the front loader. You have more than enough pressure to raise a load. Lets just talk about the loader valve. Connect a plain hose to the backhoe power beyond outlet and stick the other end in the transmission filler. That isolates the loader from all of the other hydraulics. Now start the tractor - there should be a steady stream of oil coming out of that hose and back into the transmssion. Now test all loader functions and report your results. Just that - nothing more please.

Dan

 

[Vigo]

Tested FEL, will lift SMALL amount of weight. When pushing stick forward to go down, bucket will start to Raise for micro second and then stop. Still no down on FEL unless in FLOAT.

When you operate the loader valve, it connects one side of the cylinders to the pump, and the other side to the tank. So when you try to lift the loader, if the piston seal in one cylinder (or both) is leaking from one side of the piston to the other, you will have reduced pressure trying to extend that cylinder, and you will have constant flow out the tank port even though there should only be flow there when the cylinder is actually moving. You could redirect your tank port flow from the loader valve into a bucket if you wanted to observe this.

Generally, if the cylinder were not hooked up to anything, trying to retract the cylinder with the leaky piston seal would cause pressure to leak over to the base end (the 'extension' side) and since that side has more piston surface area (because cylinder rod takes up no space on that side) the cylinder would actually EXTEND (eventually). As seen below:

However, your cylinders ARE hooked to something. So even though the pressure leaking to the base end of the cylinder DOES cause more force than the pressure acting on the rod end, the fact that the base end would have to lift the weight of the loader to cause movement, results in something close to 'breaking even' in your case, thus why you cannot lower the loader except in float.

So you have a leaking piston on one or both of the lift cylinders.

I suspect that the 3pt not working is a separate issue and you should be looking at item #20 in the diagram shown above for that one. It's also possible that the power beyond fitting for the backhoe valve is leaking everything to tank and not able to feed pressure to 3pt.

 

[TheOldHokie]

When you operate the loader valve, it connects one side of the cylinders to the pump, and the other side to the tank, or in this case the power beyond port. So when you try to lift the loader, if the piston seal in one cylinder (or both) is leaking from one side of the piston to the other, you will have reduced pressure trying to extend that cylinder, and you will have constant flow out the power beyond even though there should only be flow there when the cylinder is actually moving.

Generally, if the cylinder were not hooked up to anything, trying to retract the cylinder with the leaky piston seal would cause pressure to leak over to the base end (the 'extension' side) and since that side has more piston surface area (because cylinder rod takes up no space on that side) the cylinder would actually EXTEND (eventually). As seen below:

However, your cylinders ARE hooked to something. So even though the pressure leaking to the base end of the cylinder DOES cause more force than the pressure acting on the rod end, the fact that the base end would have to lift the weight of the loader to cause movement, results in something close to 'breaking even' in your case. Very little movement and almost no lift capacity.

So you have a leaking piston on one or both of the lift cylinders.

Or the power beyond circuit is blocked and stalling the actuator.
Or the exhaust line on the cylinder is blocked stalling the actuator
Or the lift cylinder has been connected to the regen bucket spool in reverse

There may be more but those are three other possibilties that came immediately to mind. If he follows the testing suggested we will start eliminating possibilties until there is only one. Or we could just keep on guessing.....

Dan