Kubota Help?

[Jon Hallmark]

Am I abusing my equipment or is it just too weak for the job I am trying to do?

I own a Kubota L-3940HST. A few weeks back I was clearing an area to build a shop that consisted of some brush and about 6" (caliper) pine trees. I had previously cleared the majority of the brush with a forestry mulcher, so there was mostly just brush around the trees. I was using the FEL to push and pull on the trees to loosen them up, then dig down in front of them and pop the stump and tree out of the ground. After about 2 hours of popping out trees I realized that the FEL was no longer straight. I had cobbelled up the ground so I drove out to an area that was more flat, set the FEL down, and sure enough the left side touched the ground 1 1/2" before the right. I fixed it by chaining the left side of the tractor down to trees, hooking a chain over the bucket of the FEL and pulling against a tree until it was straight again. I was not too thrilled that this had happened, but, I still had work to do, so I went back to it, being more gentle.

In the process of clearing the area I exposed some partially burried bricks apparently from an old homesite. I stuck on some trash forks and started running the tines through the dirt to loosen the bricks up at about a 60 degree angle, caught something in the dirt, the tractor rode up on the bucket and I heard a loud bang! I raised the FEL and the bucket would not curl up. I look under the tractor and there is a gallon or so of hydraulic fluid on the ground. I found a ruptured line, and thought that was all it was, so I replaced it and refilled the hydraulic fluid. Cranked the tractor and another line ruptured.

It was late, I had to go to work the next day so I had Kubota come pick it up. they have had the tractor 2 weeks now "working on a quote" to repair it. According to what they tell me, my cylinders on the bucket went bad, polluting the hydraulic system with debris and that is clogging a bypass creating too much pressure.

I guess I really have 2 questions. I am expecting too much from this tractor, should I have purchased something bigger, or a different brand?

I'm really scared of what Kubota is going to quote to make the repairs and assume I'm about to get a crash course in hydraulics. I see Baily makes cylinders that I can use to replace the bad ones, and clean up of the system sounds like a labor intense remove, clean, reinstall process that I am really not looking forward to.

I look forward to thoughts and advice.

Jon

 

[Leejohn]

I don't think you need a bigger tractor. Just go about it in a different way, so the cyls. can't bend.

 

[TripleR]

What Leejohn said, unless you get a construction grade tractor, about anything is going to have its limits. You probably need to just take it a little easier. If you will check your manual, you will probably find where what you are doing is not recommended. I do the same things with mine mind you, so I may well be in your same situation whether it is one of the "little" or "big" tractors.

 

[s219]

If you're saying you were digging out 6" pine trees with a FEL, then I'd say you're definitely doing it wrong. That is work for a backhoe, not the front loader. It's not really setup for doing stuff like that. There's a reason it's called a front "loader". It's mainly intended for moving materials, and only setup to handle very light digging/plowing (and better done with a tooth bar if you're going to).

It makes me wince to read your description about using the forks. That is definitely out of the realm of what you should be doing with a front loader in my opinion. Use smaller teeth or rakes that won't have so much leverage if they hang up. Or get a box blade and put the rippers down.

 

[J_J]

You can do what they are probably going to do.

If a hose blows, the fluid usually blows out, There may not be any trash in the hyd system. If they assume that there is debris, then they will drain , flush, replace the filters, and add new fluid, and install new hoses.

You may simply have over worked the machine, and the weakest part failed.

You should install a gage in the hyd system and monitor and trouble shoot the hyd system.

Check your relief pressure for sure.

Hyd hoses are tested at 4 times the operating pressure when new. Old hyd hoses could burst at any pressure depending on the condition of the hose.

It would not be to hard to twist the loader arms trying to lift something from one corner or edge.

Someting like this.

 

[TripleR]

We have had hydraulic hoses blow on tractors and back hoes, all we did was replace them and add fluid.

 

[J_J]

You did not say anything about warranty, just that Kubota came and you told them to fix it.

Should have gotten a written estimate, and questioned whether their logic was sound. Maybe they can find some debris in a valve and justify the repair, and say we told you.

You should always be skeptical, because they want to make money and pay the rent, and so forth.

It is hard to think the cyl exploded and then blew a hose, and then contaminated the complete hyd system.

More than likely you caused a spike in the hyd hoses and blew the hose at the weak spot. Then you did it again.

If you jam into something, you can easily cause a hyd surge/spike.

 

[DieselnHooters]

and before you ask...no you cant borrow my tractor

 

[Leejohn]

JJ he did have a cyl explode it was just 2 hoses. Eather way I would of just put the new hoses on and maybe check the relief valve. It sounds more like he was using it as a grader blade.

 

[J_J]

I am just not picking up on the the description of a cyl went bad, because after he heard a loud bang he replaced a hose and try to operate and blew another hose.

He said they told him the cyl went bad. HOW

If the spike caused the cyl to blow the seals or the piston off the end of the rod, there would be very little pressure.

I am thinking he tried to jam the bucket again and spiked the fluid again.

I believe I would have put a pressure gage in the hyd circuit and did some logical trouble shooting before calling Kubota.

You may have blown seals, you may have a bulge in the cyl wall.

 

[Jon Hallmark]

First, thanks for taking the time to respond. Let me clarify a couple of points.

Kubota is just giving me a quote to make the repairs.

Yes, the first line ruptured while I was working the tractor, the second one ruptured while the tractor was idleing, so something is going on to spike the pressure and I don't know enought about hydraulics to have a different theory than a clogged bypass. It sure seems like the pressure side of the line should be filtered, and the filter should catch the pieces of trash.

It sounds like a combination of technique that places less stress on the hydraulics and FEL are in order.

 

[Jon Hallmark]

How does this sound?
Pull the cylinders off and inspect to see if they are actually bad. JJ has a point, nothing external shows one went bad. There is no bend or leaks at the cylinder. With that in mind, I suppose I should not assume Kubota's tech is correct. Based on what I find there, I guess I should just start disassembling, cleaning and inspecting. Thoughts?

 

[J_J]

If all hyd valve levers were in neutral, the hyd fluid would just flow through all the valves.

If a relief is clogged and you cause the pressure to rise above the set relief pressure, then the pressure will rise enough to cause the weakest component to fail.

Remove the relief valve for the FEL and check/clean.

You can check your cyl by forcing the piston to the end of the extend stroke, remove the rod end hose and push the lever to more extend, and see of any fluid is coming out the rod end port. If it is, then the cyl seals are bypassing of leaking.

If you cap the other cyl hoses, you can check each cyl in the circuit.

Repeat test for other cyl.

A hyd gage is your friend.

 

[cmore]

John, just wondering what they found wrong?

 

[Jon Hallmark]

John, just wondering what they found wrong?

One of the bucket cylinders had pulled the nut off that held the piston on the end. Then a piece of the trash clogged up the bypass causing the pressure to spike and as JJ said, was causing the weakest link to fail until it was cleaned out.

FYI, when I had Kubota give me a quote it was to repair this malfunction, change the hydraulic oil, and change the motor oil. Their quote was $3,800 and some change.

I purchased 2 new cylinders from Baileys along with bushings to create the proper pin size, 2 new hoses from my local auto parts and changed the hydraulic oil, motor oil, and all of the filters for just over $675.00, with 1 afternoon of gathering stuff, and 1 afternoon of installing the parts.

Baileys bucket cylinders $96.00 each side, Kubota wanted $700 plus, and their quote only included 1 replacement.
hydraulic hoses and fittings $104 each side, the bailies cylinders had a different hydraulic port location causing my hoses to be too short.
Filter kit from ebay $140
Carquest Kubota UBT equal $45 per 5 gallon pail.

It works as good as new.

I cannot believe the markup they wanted to charge. When I buy my next tractor, I'm going to research the dealers service costs better!

 

[J_J]

Jon Hallmark,

Glad you took care of the problem your self.

Did you remember to Loctite the nut on the piston.