Kubota junk. Frustration rant

[Bing187]

Wow.
Posted this in frustration, looked at it that night, and figured based on the 190 something views and 1 comment, that nobody was offering up advice. Guess I was wrong.....

First off, Thank you for the suggestions and input, it is much appreciated. I was loaded for bear the day that it happened and not being terribly rational.. I will fill you all in on where it stands and the history of the machine to answer a few questions....

As someone researched on previous posts, the relief valve on the dipperstick was first to cause a problem. no pressure. Dealer took, brought back, guy wasn't out of the driveway yet when I tried it and it was same as when they picked it up. They took it back, second time it came back correct.

Dipperstick bending was NOT a case of abuse.. I was digging a trench in some bony ground, backhoe started making screeching noises when I extended dipperstick... Could see that piston was bent. I rebuilt the cylinder with new seals and a new piston. If digging a trench in rocky ground counts as abuse, then guilty as charged.

Control valve broke in (?) August. Tilt roll function started acting wonky, then ceased to work altogether. Took loader valve apart, tiny poppet valve had broken, stem got up into valve and scored the spool on that side... $1200 clams later, fixed.

November. Moving an old set of concrete stairs. Too heavy to lift with forks, I had them rolled forward and slid stairs about twenty feet to get to where I could slide them into dumpster... Leverage of forks bent BOTH tilt/ roll pistons. Replaced pistons in rebuilt cylinders. That one I'll take the blame for, though the cylinders could be a little beefier imo...

Now loader won't go up. Fork lift mechanic friend (smart guy, honest) looked at it Friday. Switched out quick connects, lift would work if lines for tilt/ roll were switched... After some fiddling, we determined that the lift function has pressure going to both sides of the piston.... At this point, I have narrowed it down to either loader valve issue, or 3 point hitch issue, as service at dealer has walked me through some diagnosis.... Will have a chance to work on it this week, so hopefully will figure it out....

Again, this machine has been taken care of, worked but certainly not abused.... As to "The stupidity factor" well, you don't know me, but I think that if you did you'd rule that one out.. Frustrating to read when I bought

 

[Bing187]

don't know why that cut off last sentence... Should've said Frustrating to read when I bought a new machine precisely to avoid a machine that was abused, and to avoid a bunch of piddly issues....

Thanks again to the folks that have offered up advice and good input...

Mike

 

[Rustyiron]

I think it's human nature to try to drive railroad spike with a tack hammer, that is just because you can drive up to that big rock, doesn't mean you should put it in your bucket and load it. If the manufacturer's were to build these mini machines for that service, they would weigh (and cost) 2-3 times as much, and prolly be painted yellow!:thumbsup:
We've all done it, well I certainly have. I got pretty good driving with one of the rear tires in the air, carrying too much! You can only ask so much out of these little tractors before they break.

 

[Coyote machine]

FWIW, sounds to me like you may need a bigger tractor. When you say the cylinders could be a little beefier, that sounds like you want to do things with your current tractor it isn't capable of doing. Bigger/beefier cylinders would only serve for some other part of the machine getting broken. If you can't lift what you need to and the relief valves aren't keeping you from things like valves and cylinders from breaking it sounds like OP error in purchasing not enough machine, and or pushing the machine too far beyond it's abilities. Neither is the machine's fault; and it definitely does not make the machine a piece of junk. Not here to 'fault' you, just giving my candid opinion based on what you've stated to date. Sometimes we need the perspective of those not as close to, or as invested in the problem to see clearly. An example below from my own learning curve.

I had a similar problem when I bought my first tractor. It was a 3 cylinder Kioti, DK-35. I was bending the 1/2 moon shaped loader pieces due to pushing too hard, back-dragging with too much force, etc. New tractor, inexperienced OP, me. I found out after several repairs that I needed a stronger and greater lift capacity loader.

I traded for a 4 cylinder DK-40 with a 1750# additional lift capacity, and after 750+ hours no problems with any loader pieces bending. Lesson learned, at great expense. Had I kept going with the lesser capacity tractor that would have become very expensive to keep repairing over time.

 

[Bing187]

Thanks for the replies. I honestly don't think that a bigger machine is necessarily the answer, though I can see why someone might think so. Have really only encountered problems with things being too heavy or too big to move a handful of times. I bought the machine for two reasons; to work on my 8 acres of woods, bringing in firewood, maintaining 800 ft of driveway. Also work as a general contractor on my days off from professional fire dept. some electrical trenches, deck footings, etc. it has worked out pretty well overall, as it's small enough that I can move it with a pickup, and it doesn't wreck lawns if I do work where there is a finished yard... A full size backhoe would be a big jump. Now... Maybe the times that I have broken it were from me being, ahem, overzealous.. But not the majority of the time. As of now, I'm taking it to Norfolk power on Wednesday for them to at least diagnose. I'm at a loss as to what's up...
Thanks for your replies
Mike

 

[skyhook]

Have the relief valves been tampered with, they could be set too high for that machine, just a thought.

 

[MinnesotaEric]

I am no hydraulics expert but my first impression is that your hydraulic system is contaminated. You have changed several major components and the initial problem could have been as minor as o - ring problem.These rubber component's when they get cut up into little tiny pieces like to float around in the system and when they float around here and there the problem floats around also. The metallic components tend to bottom out and collect near the strainer and or into the filter. The rubber component's o - rings, glid rings, seals etc. are easily disturbed and move around in the system. The Teflon / pipe joint needs to be just behind that first thread, nothing over.Just some thoughts. Later

You don't need teflon pipe tape whatsoever. Simply use LocTite 5452. Although pricey, 5452 seals and never hardens. Better yet, if it gets into the hydraulics oil, it doesn't muck them up.

http://www.grainger.com/ec/pdf/Loctite-5452-Sealant-Pnematic-Hydraulic-Data-Sheet.pdf

 

[aczlan]

You don't need teflon pipe tape whatsoever. Simply use LocTite 5452. Although pricey, 5452 seals and never hardens. Better yet, if it gets into the hydraulics oil, it doesn't much them up.
http://www.grainger.com/ec/pdf/Loctite-5452-Sealant-Pnematic-Hydraulic-Data-Sheet.pdf

I really like Amazon.com: Oatey 31230 Pipe Joint Compound with PTFE with Brush, 4 fl.Ounce: Home Improvement for that purpose. Its rated to 3000PSI for gases and 10,000PSI for liquids.

Aaron Z

 

[MinnesotaEric]

I really like Amazon.com: Oatey 31230 Pipe Joint Compound with PTFE with Brush, 4 fl.Ounce: Home Improvement for that purpose. Its rated to 3000PSI for gases and 10,000PSI for liquids.

Aaron Z

I've used that very stuff on NPT iron pipe, but it is not formulated specifically for hydraulics, whereas 5452 (which is replacing an older product) is formulated for hydraulics, including for use on sealing flanges that will be exposed to hydraulic oil.

Ad copy: 5452 Thread Sealant is ideal for sealing the fine threads of hydraulic and pneumatic connectors. Like other Loctite® brand anaerobic sealants, this product seals and secures metal pipes and fittings, filling the space between the threads and curing to eliminate leak paths. The thixotropic nature of 5452 is suitable for large diameter pipes and will seal on mating surfaces of flare style fittings – filling scratches and surface imperfections. This product is also useful with dry seal fittings, such as O-ring boss style connectors, by preventing the rotation that ultimately leads to leakage. After assembly, this product cures considerably faster than traditional anaerobic thread sealants. It does not contain any filler or particles that could contaminate system fluids, foul valves, or clog fine filters and screens.

 

[heviduty]

My loader suddenly slowed to a crawl one day. So slow you almost had to sight between the bucket and a tree to see it move. I couldn't figure out what was wrong, then noticed a rear remote was in detent position. I had added the remote along with two others for TnT with float detents, but this one has "on" detent to supply a wood splitter, phd, etc. I suppose a tree limb had pushed it to the detent position; anyhoo, it was choking the hydraulics. Once the handle was flipped back to the neutral position the hydraulics returned to normal.

 

[TSO]

I would agree that it is not necessarily due to abuse. My buddies L3540 only had about 200 hrs (of just PTO work) on it when his hydraulics started acting up. Dealer had to split the tractor in half to fix it. Ended up being some very small part inside of the internal valve. Definitely not his fault. Probably not even Kubota's fault --- was probably a purchased component. The part was updated to prevent the issue. I think he had a hydraulic issue on his new B2920 as well, but I think that ended up being a cylinder seal or something else minor.

 

[The Fred]

Bing187 I feel your pain brother......

You won't get any shoulders to cry on with the orange crowd here, ask me how I know?

Good luck, Fred

 

[DavesTractor]

What many folks do not consider, is that on most if not all compact tractors, when the loader spool valve is centered, there is no pressure relief for the loader lift or tilt rams. When you apply hydraulic flow to those rams, like you do when you use the joystick, you can only apply an amount limited by the pressure relief. But as soon as you let go of that valve and let it center, the oil in those cylinders is trapped with no relief. Not a problem you say, if it lifted it with the available pressure it should carry it. The problem comes when you then apply more force to the bucket. The oil has no relief to get to as it is on the other side of the valve, so a rod bends or a hose blows if it becomes severely overloaded. For example, say you have a set of forks on the tractor and you get stupid and decide to try to pull a tree stump out of the ground. You get the forks under the stump and lift and it won't lift it. So you say to yourself "I think I'll lock the diff and put it in 4wd, raise the rpm and just ram/push this thing out of the ground". Your forks are down at an angle and you give a big shove and the leverage on the forks acting against the immovable object causes the pressure in the tilt cylinders to spike to 6000 psi, or even more. At that point you either spin and lose traction, the stump gives, a hose blows or a cylinder rod bends/breaks. And if you had the tilt cylinders extended much, you for sure bend the rod.

I don't think my example is as clear as I'd like it to be, but I hope I made the point. Some loaders/backhoes will have a relief built in to avoid this, but I think it is rare in the CUT size tractor. In fact I do not know of any CUT that has this sort of a relief on the loader. The Mahindra 3720 backhoes built in the last couple of years have a bucket cylinder relief that will allow the bucket cylinder to retract before bending. Otherwise if all the stars lined up and you were digging deep and curled the bucket around a root and extended that cylinder all of the way, then horsed on the boom or tried to drive forward, that bucket cylinder rod was vulnerable to bending. It's an operator problem....but it happens and I commend Mahindra for spending some more $$ and putting a relief on that side of the valve.

As to the OP, I think he has had some bad luck combined with being a bit aggressive with a machine that is too small.

 

[skyhook]

I hear what your saying, DT....but all hydraulic cylinders are protected by relief vales.

The problem comes when you then apply more force to the bucket. The oil has no relief to get to as it is on the other side of the valve, so a rod bends or a hose blows if it becomes severely overloaded.

I believe the only way this would happen is if the relief valve has been "increased".
I could be wrong, I'm certainly no expert on hydraulics, but I'm learning.

 

[skyhook]

Bing187 I feel your pain brother......

You won't get any shoulders to cry on with the orange crowd here, ask me how I know?

Good luck, Fred

I'm not a member of the orange crowd any longer....
I really don't think this has anything to do with color, it's a hydraulic issue....
trying to exceed the machines capability's will give you exactly what you asked for.
There are threads here where some have decided to "replace cylinders with larger ones" in hopes of lifting more....:confused2:
There are also some that would use the original cylinders and just increase "relief vale pressure" :confused2:
You get what you pay for, and I've just realized, sometimes, you don't even get that.

 

[Scooby074]

I hear what your saying, DT....but all hydraulic cylinders are protected by relief vales.

I believe the only way this would happen is if the relief valve has been "increased".
I could be wrong, I'm certainly no expert on hydraulics, but I'm learning.

Not when the valve is in neutral on a typical open centre tractor.

The lines out to the lift cyls etc. are blocked by the valve spool when the lever is in neutral (its why the loader doesnt fall when you lift it and let go the lever) . When you ram the tractor loader into something (using the wheels/engine) its very possible for you to apply enough force (via the tractors motion) to the piston to cause a spike in pressure in that closed circuit. The pressure relief will not even see that pressure spike because the spike cant "get past" the spool. Thats when things bend or blow depending on whats the weakest link in that circuit.

 

[DK35vince]

There are threads here where some have decided to "replace cylinders with larger ones" in hopes of lifting more....:confused2:
There are also some that would use the original cylinders and just increase "relief vale pressure" :confused2:

Guilty.
I've done a bit of both with my loader

 

[DavesTractor]

I hear what your saying, DT....but all hydraulic cylinders are protected by relief vales.

I believe the only way this would happen is if the relief valve has been "increased".
I could be wrong, I'm certainly no expert on hydraulics, but I'm learning.

I don't think you are following me, perhaps because I have not been very clear. It is not very obvious unless you understand where the relief valve is positioned in the system, and the hydraulic path to get to it. I think some industrial and construction equipment have reliefs beyond the spools, but not the typical compact tractor.

We are talking open center systems, let's start with that. The cylinders are protected from being over pressurized by the pump via the system relief or the relief on the spool valve if it has one and if it is set lower than the main system. So if you had 15,000 lbs in a bucket that was resting flat on the ground (your gold collection) that was only designed to lift 2000 lbs, sure enough when you tried to lift it the oil would pressurize the cylinders to the relief pressure (maybe 2500 psi) and then spill over the relief. No harm done. But once the spool is centered, the oil in the cylinders has no way of getting back through the closed spool to get to the pressure relief. So take that same load of 15,000 lbs of gold (about half a yard) and set it gently in the already raised bucket and do not touch the joystick. Let's pretend we actually have that much weight that would fit in the bucket and let's forget that we would blow tires and break axles and tip and such. So we have our hands off the joystick and have the loader a couple feet in the air so it is not resting on the ground. We gently put our 1/2 yard of gold into the bucket and what happens? The oil is in a conundrum, if that can happen to oil. It can't work it's way back past the spool except by internal leakage....and that is slow. The pressure relief in small tractors is blocked from cylinder pressure when the spool is centered, so it can't find a pressure relief. It may try to leak past the cylinder pistons/seals, but that is slow just like trying to leak past the spool valve. All of the sudden we have a huge, huge amount of pressure in the cylinders and we either blow hoses, blow fittings, explode a cylinder (surely a hose first) or other carnage like bent cylinder rods that allow the load to fall to the ground. If a cylinder is very far extended when it gets a huge pressure spike, then the rod will often bend before a hose blows. If the cylinder is retracted and it it's strongest position, probably a hose will blow.

I hope I made this clearer and not more confusing.....

 

[ovrszd]

My loader suddenly slowed to a crawl one day. So slow you almost had to sight between the bucket and a tree to see it move. I couldn't figure out what was wrong, then noticed a rear remote was in detent position. I had added the remote along with two others for TnT with float detents, but this one has "on" detent to supply a wood splitter, phd, etc. I suppose a tree limb had pushed it to the detent position; anyhoo, it was choking the hydraulics. Once the handle was flipped back to the neutral position the hydraulics returned to normal.

I call those "stupid human tricks". Not calling you names. Just what I call them. I do them almost on a daily basis......

 

[ovrszd]

I don't think you are following me, perhaps because I have not been very clear. It is not very obvious unless you understand where the relief valve is positioned in the system, and the hydraulic path to get to it. I think some industrial and construction equipment have reliefs beyond the spools, but not the typical compact tractor.

We are talking open center systems, let's start with that. The cylinders are protected from being over pressurized by the pump via the system relief or the relief on the spool valve if it has one and if it is set lower than the main system. So if you had 15,000 lbs in a bucket that was resting flat on the ground (your gold collection) that was only designed to lift 2000 lbs, sure enough when you tried to lift it the oil would pressurize the cylinders to the relief pressure (maybe 2500 psi) and then spill over the relief. No harm done. But once the spool is centered, the oil in the cylinders has no way of getting back through the closed spool to get to the pressure relief. So take that same load of 15,000 lbs of gold (about half a yard) and set it gently in the already raised bucket and do not touch the joystick. Let's pretend we actually have that much weight that would fit in the bucket and let's forget that we would blow tires and break axles and tip and such. So we have our hands off the joystick and have the loader a couple feet in the air so it is not resting on the ground. We gently put our 1/2 yard of gold into the bucket and what happens? The oil is in a conundrum, if that can happen to oil. It can't work it's way back past the spool except by internal leakage....and that is slow. The pressure relief in small tractors is blocked from cylinder pressure when the spool is centered, so it can't find a pressure relief. It may try to leak past the cylinder pistons/seals, but that is slow just like trying to leak past the spool valve. All of the sudden we have a huge, huge amount of pressure in the cylinders and we either blow hoses, blow fittings, explode a cylinder (surely a hose first) or other carnage like bent cylinder rods that allow the load to fall to the ground. If a cylinder is very far extended when it gets a huge pressure spike, then the rod will often bend before a hose blows. If the cylinder is retracted and it it's strongest position, probably a hose will blow.

I hope I made this clearer and not more confusing.....

That's crystal clear to me. And it accurately explains what happened to my Kubota L4400's bucket tip cylinders when I extended them with a tree puller on, pointed down, latched onto a tree. I returned the joystick to neutral and put the tractor in reverse to try to pry the tree out of the ground. When I backed up it simply bent the cylinder rods. As you described, the relief valve was worthless to prevent it.