BH75 Kubota Hoe On GL3240 Leaking Down

[hunelmea]

Purchased new GL3240 w/FEL and BH75 back-hoe in June this year. Since day 1, the BH leaks down. Mostly the boom, probably due to the weight, but even the stabalizers will leak down completely overnight.

When operating the tractor, the boom constantly moves down and you must reach back and raise it. Of course this opens the seat switch shutting down the engine, usually when you are climbing out of a ditch or something more difficult.

The hoe also seems to be low in power and very slow to react expecially when using the crowd and bucket at the same time or boom, etc.

Most of the valves have been worked by the dealer (in the shop 4 times) and it is back in the shop now for the same problem. No other problems with the tractor. Even the FEL works perfectly.

Anyone have any ideas?

 

[art]

The bulk of the time the seals in the cylinders are the problem. We have rebuilt a few but you seem to be having problems with more then one cylinder and that is all we normally see at a time.

It does sound like you have a problem!

 

[hunelmea]

Thanks for everyone's input.

Just talked with the dealer and they are going to remove the lines from the cylinders and cap them. If any of the cylinders still leak down, then that should indicate internal leakage in the cyliinders.

If such is the case, maybe the repair will help with the lower power of the BH issue.

 

[Wayne County Hose]

Thanks for everyone's input.

Just talked with the dealer and they are going to remove the lines from the cylinders and cap them. If any of the cylinders still leak down, then that should indicate internal leakage in the cyliinders.

This is not a conclusive test at all. There are different volumes on either side of the piston seal. The rod takes up cylinder volume remember. So even if you assembled a cylinder with no piston seal and capped it, the cylinder would only drift until the pressures equalized. Your dealer doesn't know what they are doing. My bet is that the manufacturer is using an inexpensive valve and it's the valve not holding.

When I rebuild a cylinder, I put a valve and a gauge on both ports of the cylinder, the gauge is between the valve and cylinder obviously. I retract the rod all the way and run the gauge up to 2500 psi then I shut both valves. If the gauges equalize in pressure then I have a bad piston seal. If the gauge on the rod side stays constant and the gauge on the piston side stays at zero, then the piston seal is good.

 

[Tractor Dr.]

How hard is it to replace a seal in a cylinder? I have a L3130 with bucket leakdown and will likely need to rebuild one or both of the bucket cylinders. Are there other parts that should be replaced while it is apart?

TD

 

[hunelmea]

Thanks for the input. Will go by the dealer today and see how they are doing. Maybe suggest that they try using the two gauge set-up you described.

 

[brandoro]

When I first bought my Landpride BH all the cylinders leaked down fairly quickly. The real problem was the outriggers, I would have to keep bumping them down to hold the tractor steady while digging. For driving the tractor around doing other stuff I would put the transport lock on the boom so not a big deal there. Since everything leaked down the repair was to change out the entire valve set (body?). This was done under warranty. If I leave the transport lock off the boom it will be on the ground by morning but the leakage is low enough that it is not a problem.
Except that bumping the outriggers had become such a habit that I still do it sometimes and occasionally end up with the back of the tractor way up in the air.

 

[bandit67]

I don't quite understand the complaints of the leakdown on these small backhoes. They're not really designed to NOT leak down - we're not paying for that feature like you do on the big commercial equipment. My BH75 boom will leak down a bit while the tractor is in use if I don't put the boom pin in, and so does the bucket. The bucket will drop down quite a bit overnight, and the boom would drop all the way overnight if I didn't pin it.

I don't ever have more than a 1/2" leakdown on the stabilizers though, but when I store the hoe off the machine, the boom pin is in and I run a tie-down strap between the stabilizers to keep them from dropping.

Even the new M59 has a boom lock, and I would guess that the B26, L39, & M59 booms will leak down some during use, though probably not as fast as the smaller lighter duty hoe like the BH75. I figure that Kubota gave me a boom pin for a reason, so I use it whenever I'm not digging with the hoe. I also figure that all that all that backhoe weight bouncing around when I'm doing loader work on rough terrain is hard on the backhoe hydraulics, so why not use the boom pin to take some of the stresses off the cylinders.

I honestly have not heard of any manufacturer's smaller, non-commercial backhoes NOT leaking down. I'm sure it would cost us all a bit more to buy a non-leak-down backhoe.

To the OP, you must have been looking to save some $$ since you put the little BH75 on your Grand L, instead of the BH90. I love my BH75, but I personally would spend the extra $$ on the BH90 if I bought a GL series machine. But we all need to save money somewhere. Even Kubota, so we have to just deal with some backhoe leakdown because I think it stems from their parts. But, OP, you aren't the only one experiencing leakdown, and your dealer should know that, but if they want to waste their time trying to "figure it out", then that's their problem. Of course, by not explaining how common leakdown is on the BH75, they're wasting your time, too.

As for the multi-function, the BH75 is capable of it, but it takes some practice, and you need to have the hydraulic flow high enough to accomplish multiple simultaneous functions, but it can't compare to the bigger, higher flow commercial machines, so if you're used to them, you might be dissapointed in yours.

 

[hunelmea]

Bandit67:

Appreciate your comments, but if you are switching from the loader and BH numerous times during the day as I was while clearing a small creek bed for a culvert, then pinning the boom is just not practical.

In addition, the leakage here is much more than you are describing. If I don't continously reach back (and I mean every 5 min or so) and raise the boom, the bucket will drag the ground. The RH stabilizer will creep down and hang outside the tire and if I'm not careful, I'll knock it off. To me, this is totally unacceptable.

Regarding the BH75 vs. the BH90, if I had it to do alll over again, I likely would have gotten the 90. With the exception of it being physically larger with slightly more breakout force, not sure there is a lot of difference between them. I've read similar reports about the 90's hydraulics. In fact, some report that the 90 is even slower than the 75.

Hopefully, the problem can be repaired. Thanks again for your comments.

 

[bandit67]

OK, well then that is too much leakdown, and they need to get it fixed for you.

BUT, you will still experience some leakdown, even during tractor operation when all is back to design spec.

I've just gotten in the habit of pinning the boom if I won't be back in the BH seat for 20-30 minutes and will be bouncing around on rough terrain. When jumping back and forth every few minutes between FEL and backhoe work, I usually don't pin the boom, but it will end up dropped an inch or two in 5-10 minutes.

As for the simutaneous multi funtions, DON'T operate a real excavator if you can help it, because it'll be a big bummer when you get back to your little BH75 until you get used to the functions again.