L3901DT Hydraulics Not Working

[North Idaho Wolfman]

These tractors are not very old. I own a 3 year old one and broken shafts on a hydraulic pump would not give me warm fuzzies. Have you ever seen this on an L01?

Dan

Not an 01 specifically, but on the same type of pump.
I think it has to do with a small amount of water or other debris in the hydraulic fluid or even in the motor oil.
With water in hydraulic fluid it will lock up the pump for a split second and either crack the drive gear coupling in two or break the shaft (seen both).
The other possibility is water in the oil then gets trapped in the space between the shaft and the gear and cracks the collar in two,
Both are extremely rare.
You see quite a bit of up tick in cases of pump failure after (even months later) a super cold spell.
I think sometimes it might be caused by cold parts and shock loads or warm parts and cold fluids.

 

[TheOldHokie]

Not an 01 specifically, but on the same type of pump.
I think it has to do with a small amount of water or other debris in the hydraulic fluid or even in the motor oil.
With water in hydraulic fluid it will lock up the pump for a split second and either crack the drive gear coupling in two or break the shaft (seen both).
The other possibility is water in the oil then gets trapped in the space between the shaft and the gear and cracks the color in two,
Both are extremely rare.
You see quite a bit of up tick in cases of pump failure after (even months later) a super cold spell.
I think sometimes it might be caused by cold parts and shock loads or warm parts and cold fluids.

I will be very interested in how this plays out. That pump is a $1200 item...

 

[JohnMackenzie]

These tractors are not very old. I own a 3 year old one and broken shafts on a hydraulic pump would not give me warm fuzzies. Have you ever seen this on an L01?

Dan

I see that you and I have pretty much the same two tractors, makes it convenient I suppose. The only thing I was thinking about the shaft being broken would be what the hell would cause that to happen, because that's a serious issue. But I see Wolfman said what could cause it. I would imagine it is quite rare but with my luck I would have the 1 in a million that will break, I'll probably bite the bullet and take the pump off tomorrow to at least rule that out if that's not the case. I remember a story my neighbour told me about how when he was a kid his father and someone else were driving and long story short they did a valve job on the side of the road... it didn't need a valve job. On another note, Dan have you had any problems with the steering box or dynamo on your 7200, because having constant problems with them is what inspired me to buy this tractor, that and the backhoe.

 

[TheOldHokie]

On another note, Dan have you had any problems with the steering box or dynamo on your 7200, because having constant problems with them is what inspired me to buy this tractor, that and the backhoe.

Based on what I saw in the parts diagram those drive gears are fed pressuruzed engine oil via a pipe on the side of the case. I cant imagine any reason for them to fail. I am very interested in seeing what you find.

The steering box on the B7200 is too light for a loader tractor and I have had to repair mine a couple of times. Its on its way out again.

Dynamo went south several years ago and I put a cheap aftermarket replacement on and its been fine..

 

[JohnMackenzie]

So I'm sure that those who were following my tractor saga are curious whether I was able to fix the hydraulic issues I was having. I did find the problem and fix it, troubleshooting was a pain for me because I don't deal with hydraulic problems on tractors often. Regardless, Occam's razor proves true once again, what happened exactly isn't clear to me, ultimately it came down to a clogged suction screen and hydraulic filter. As mentioned previously I had changed the oil and filter at the first 35 hrs and at 395 hrs, currently it's at 448.9 hrs, keep in mind the manual says to change oil and filter after the first 50 hrs and every 400 hrs, which is why I hadn't put too much thought into the idea that they would be the problem. On top of that I wouldn't have thought that would completely cause all function of hydraulics to fail. Now on to the reason to why this was able to happen, whatever was in the oil is only partially magnetic which is also why after having pulled the filter off, I didn't think that was the issue either (lack of particles on the filter magnet). What bothers me is the most is how did that stuff get into the system, now there's three possible explanations and all are disconcerting to me, and two of them should be should worry owners of new kubota tractors.
#1 when the transmission castings were made, the company didn't do their due diligence and clean the castings of the sand before assembly of the tractor. Now this seems the most plausible and least concerning, the question is why didn't the first two oil changes keep this problem from happening in the first place, also what finally caused the particles to get suspended in the oil.
#2 The least plausible but most concerning from a quality standpoint, the tractor is eating itself from the inside out. However I don't think this is the case because like I said, the majority of the particles aren't magnetic, if my gears were severely prematurely wearing, the magnet would've been full of it. Also at 448 hrs I don't believe that to be the case.
And finally #3 Someone put that stuff in there, if that's the case then I've got some other stuff to worry about.
Anyways thanks for your time and suggestions everyone, and remember to clean your suction screens and change your filters!!

 

[Russell King]

Could it be something like the linings of the brakes? I recall seeing some posts on here about something disintegrating and clogging up the tractor.

 

[JohnMackenzie]

Could it be something like the linings of the brakes? I recall seeing some posts on here about something disintegrating and clogging up the tractor.

That's probably what happened, I didn't think of that at all, I wonder if the parking brake got left on for a while

 

[TheOldHokie]

So I'm sure that those who were following my tractor saga are curious whether I was able to fix the hydraulic issues I was having. I did find the problem and fix it, troubleshooting was a pain for me because I don't deal with hydraulic problems on tractors often. Regardless, Occam's razor proves true once again, what happened exactly isn't clear to me, ultimately it came down to a clogged suction screen and hydraulic filter. As mentioned previously I had changed the oil and filter at the first 35 hrs and at 395 hrs, currently it's at 448.9 hrs, keep in mind the manual says to change oil and filter after the first 50 hrs and every 400 hrs, which is why I hadn't put too much thought into the idea that they would be the problem. On top of that I wouldn't have thought that would completely cause all function of hydraulics to fail. Now on to the reason to why this was able to happen, whatever was in the oil is only partially magnetic which is also why after having pulled the filter off, I didn't think that was the issue either (lack of particles on the filter magnet). What bothers me is the most is how did that stuff get into the system, now there's three possible explanations and all are disconcerting to me, and two of them should be should worry owners of new kubota tractors.
#1 when the transmission castings were made, the company didn't do their due diligence and clean the castings of the sand before assembly of the tractor. Now this seems the most plausible and least concerning, the question is why didn't the first two oil changes keep this problem from happening in the first place, also what finally caused the particles to get suspended in the oil.
#2 The least plausible but most concerning from a quality standpoint, the tractor is eating itself from the inside out. However I don't think this is the case because like I said, the majority of the particles aren't magnetic, if my gears were severely prematurely wearing, the magnet would've been full of it. Also at 448 hrs I don't believe that to be the case.
And finally #3 Someone put that stuff in there, if that's the case then I've got some other stuff to worry about.
Anyways thanks for your time and suggestions everyone, and remember to clean your suction screens and change your filters!!

Goos news is thats a lot cheaper and easier than a blown pump and/or drive. New filter clogged in under 50 hours is concerning. Could you point me to the suction screen? I am only aware of the filter.

Dan

 

[Ricklesss]

I’ve got a very similar problem with my 3 year old L3901 only it’s a hydrostatic.
It drives fine and I have power steering but the three point and bucket functions don’t work.
i will change the filter tomorrow but wondering where to access this suction screen?

 

[TheOldHokie]

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I’ve got a very similar problem with my 3 year old L3901 only it’s a hydrostatic.
It drives fine and I have power steering but the three point and bucket functions don’t work.
i will change the filter tomorrow but wondering where to access this suction screen?

AFAIK there is no screen.

Dan

 

[Ricklesss]

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AFAIK there is no screen.

Darn it. Thanks anyway. Gonna talk to the dealer see what they say.

 

[Yotekiller]

Very informative thread that I enjoyed reading. We certainly have some knowledgeable fellers here!
I'm due for my first fluid change as well and now want to check this hydraulic screen out....

 

[TheOldHokie]

Dont go off the deep end. Disconnect the inlet supply hose at the loader valve and check for flow.

Dan

 

[TheOldHokie]

Very informative thread that I enjoyed reading. We certainly have some knowledgeable fellers here!
I'm due for my first fluid change as well and now want to check this hydraulic screen out....

There is no mysterious "screen" to check out. The spin on hydraulic filter does that job on an L01/L02.

Dan

 

[Ricklesss]

Thank you Dan. I will try that tomorrow.
Picked up all my filters today and chatted with a tech at Kubota.
He said he’s seen some with faulty thumb switches for the third function that will give the symptoms I’ve got. Maybe a fuse?
Also mentioned if the third point limiter switch is out of adjustment it can do something weird, but told him I lowered my box blade to the ground and now it won’t go back up. So it ain’t that!

 

[TheOldHokie]

Thank you Dan. I will try that tomorrow.
Picked up all my filters today and chatted with a tech at Kubota.
He said he’s seen some with faulty thumb switches for the third function that will give the symptoms I’ve got. Maybe a fuse?
Also mentioned if the third point limiter switch is out of adjustment it can do something weird, but told him I lowered my box blade to the ground and now it won’t go back up. So it ain’t that!

A stuck solenoid valve or even a manual valve will block the power beyond circuit and give those symptoms. Just unplug the solenoids on the third function to eliminate that possibilty. A better test is to disconnect the power beyond hose ,(upper left) at the hydraulic outlet block and see if that fixes the loader.

If you have a backhoe you akso need to verify the couplers at the rear are properly connected ( loooed together).

Dan

 

[Ricklesss]

Dan, thank you very much for taking the time to give me that advice.
It took me a little while to learn where the solenoids were and how to remove them.
I was able to remove them both and it did not change anything.
I also put it back together and tried manually moving the valves and nothing.
Then I removed that upper left hose down on that block and did not get flow, even when moving the lever, other then the little bit dribbling out of the hose.
Am I screwed? Dang it!

 

[TheOldHokie]

Dan, thank you very much for taking the time to give me that advice.
It took me a little while to learn where the solenoids were and how to remove them.
I was able to remove them both and it did not change anything.
I also put it back together and tried manually moving the valves and nothing.
Then I removed that upper left hose down on that block and did not gete. flow, even when moving the lever, other then the little bit dribbling out of the hose.
Am I screwed? Dang it!

You should be getting flow out of tje upper left hose. Remove upper right at the loader control valve and check there.

Dan

 

[Ricklesss]

I think I made an error in my diagnosis.
I just remembered, when I manually pushed in the button on the third point solenoid it did actually open the grapple, but I could not close it by pushing the other manual button.
Later this afternoon, I will retry the manual buttons again and also try the hose at the upper right control valve on the loader control valve.

 

[TheOldHokie]

I think I made an error in my diagnosis.
I just remembered, when I manually pushed in the button on the third point solenoid it did actually open the grapple, but I could not close it by pushing the other manual button.
Later this afternoon, I will retry the manual buttons again and also try the hose at the upper right control valve on the loader control valve.

The manual buttons should be spring loaded and self centering. Verify that visually.

If you got the grapple to open you had hydraulic flow so thats encouraging.

I would suggest disconnecting the inlet hose on the 3rd function valve and checking for flow there just like you did at the hydraulic block. If you have flow into the 3rd function valve you should also have flow out.

Dan