Kubota M59 Boom Cylinder

[crudolph]

Hi folks,

A couple of weeks ago I found out that the boom cylinder on my backhoe was defective. Previously I noticed that my backhoe couldn't fold all the way back to lock, leaving about 2 inches before it could bottom out.

I took the cylinder off and brought it to my local dealer. Apparently the design of this cylinder for the M59's is a known problem and they have re-engineered it. It took a bit of back and forth between my dealer and Kubota to get them to cover the cost (~2,000 for a new one), and given the low hours on the machine, they agreed.

A two man job and in about 10-15 minutes I had it back on and running again. Getting the support pins out initially was a bit of a chore though .

Cheers,
Chris.

 

[TBarD]

Several of the other M59 guys on here have reported the same thing, although I haven't seen the problem with mine yet (sounds like it may be only a matter of time however). I'm impressed that you were able to remove the boom cylinder given the weight involved. Can you comment on how this was done - would be handy to be able to do this without having to transport the tractor if it should ever be necessary to replace the cylinder on my machine.

I agree that removing the large pins can be tough. When I installed the thumb on mine (another $2k) I had to remove the main bucket pin. Took at least 30min with a steel drift and a sledge to get that sucker out of there!

 

[crudolph]

It's definitely a 2-man job but here is what we did:

Taking it off:
- Disconnected the backhoe from the machine.
- Removed the 3/8" bolt from the the top and bottom pins
- Decided to remove the upper pin first. I put a piece of board under upper boom cylinder and the boom, so that when the pin comes out it doesn't drop down.
- The pin sticks out maybe 1/8" so I hit it with the sledge and it almost shot all the way out - very happy about that.
- My father-in-law held the boom cylinder while I knocked the pin out.
-- I used the back-hoe locking pin as a drift but used a bigger one to get it started.
- Once the top pin was off, we could angle it out a bit to disconnect the two hydraulic lines. They are a compression type so came off pretty easily.
- Rested the cylinder against the boom and did the same trick with the bottom pin. This pin was definitely tougher to get started and took maybe 5 minutes of fiddling. We held the drift in a bar clamp to keep fingers away and one person kept it straight while another took swings with the sledge.
- Once it was started I used the back-hoe lock pin to drive the pin all the way through. Nice thing about that is it prevented the cylinder from dropping as it acts as a temporary pin that can be easily manipulated.
- With both pins out and the lines disconnected it can now be moved. It's not really that heavy - maybe 80 pounds (hard to say as I didn't weigh it).

Putting the new one on:
- The boom cylinder needs to roughly be in place to get the hydraulic lines on. I used the back-hoe lock pin again on the upper portion to support the cylinder.
- Reconnecting the lines was easy with the cylinder in alignment.
- Connect up your hydraulic lines to the backhoe, start it up and check for leaks.
- Grease up your pins
- Again I started with the top pin and beginning with the beveled end of the pin (one part is more bevelled that the other) got it started at one end. You need to look through the other end to make sure everything is aligned. If the hole from the upper cylinder isn't aligning, just manipulate your hydraulics (very gently) to get it aligned.
- The upper pin went in smoothly and as it went though, it pushed the back-hoe lock pin out (though it's not much work to hold it in place for a few minutes while the pin is started.
- Tapped the pin a bit further out to align the holes for the 3/8" bolt, tapped it back in place, and installed the bolt.
- For the bottom pin you need to gently manipulate your hydraulics to get it aligned with the holes. I didn't need the back-hoe lock pin to hold anything in place since most of the weight is held by the upper.
- Since the bolt hole is in a different position than the upper cylinder you need to make sure to align the holes as best you can before starting the pin.
- Installed the 3/8" bolt and voila it was all installed.

That's how I did it and so far so good. I'm sure there are better or more efficient ways of doing it, but I'm a virgin when it comes to working with hydraulics.

Cheers,
Chris.

 

[rScotty]

I don't know that all of them had the boom cylinder problem, but some did and word is that they are good about taking care of it. When mine did the same thing, Kubota warrantied the cylinder and sent a guy out to replace it. About an hour job. Since it was about a month out of warranty, I had to pay for the hydraulic fluid that was lost.
The old style cylinder was part YW400-00104, the new improved cylinder is YW400-00105.

I wonder if it would help future owners if we list serial numbers?
My tractor is serial # 50419 with backhoe # A0707. Bought summer of '08.

There is also a mandatory campaign to replace an intake hose connecting the manifold to the turbo. Affects some L40, L50, M50xx tractors, and all M59s from # 50001 to # 51294. I couldn't see anything wrong with the old hose; the new one didn't look much different.
good luck, rScotty

 

[crudolph]

My tractor serial # 50475
My backhoe serial # A0629

I also pinged my dealer to find out about the intake hose. Thanks for that information.

Cheers,
Chris.

 

[TBarD]

Mine is M59 Serial# 51282, BT1200V backhoe #A1052 - original owner bought in early 2009 I think. It has about 330 hours at this point. So it is a few hundred machines later on, maybe it will have the newer cylinder maybe not. Since I bought mine used from a private party rather than a dealer and it is well out of warranty I am dubious that Kubota would replace the part should it fail. Chris, thanks much for the info on how you replaced it. Doesn't sound that hard, and in my remote location it would probably be easier to replace it myself than haul the machine to a dealer, should the cylinder eventually fail.

 

[CGDuner]

It sounds to be a common problem among earlier M59's but I also had the same boom problem. Worked fine up to around 130 hrs then the VERY SLOW retract started happening. My machine was out of warrenty but I checked with my local Kub dealer. I told them of the problem I was having & that I'd like them to fix that & do away with any "cushion" that was built into the cylinder. They said they could only repair it only to Kubota's specs??? I said OK, thanks & left.

When I had time, pulled the cylinder off & took it to a local hydraulic shop. In about 3 days they had it torn down, diagnosed, damaged rod nut removed & rod rethreaded, "needle cushion" cut off & new seals(metric, shipped in) installed for a tad over $600. Money VERY well spent as it works better than when new.

As for the removal & assembly I'm sure 4 hands are better than 2 but it was an easy 1 person job. Mine was just the opposite of the guy said before as the top(boom base end, stick base end) pin was tight but not real crazy. When I reassembled I sanded(more or less smoothed) the the bore of the hole(s) in the actual boom & it went together no problem.

Sorry don't have any serial #'s handy but it is a 2009 model year. If for any reason someone wants them can put up later.

 

[rScotty]

It sounds to be a common problem among earlier M59's but I also had the same boom problem. Worked fine up to around 130 hrs then the VERY SLOW retract started happening. My machine was out of warranty but I checked with my local Kub dealer. I told them of the problem I was having & that I'd like them to fix that & do away with any "cushion" that was built into the cylinder. They said they could only repair it only to Kubota's specs??? I said OK, thanks & left.

When I had time, pulled the cylinder off & took it to a local hydraulic shop. In about 3 days they had it torn down, diagnosed, damaged rod nut removed & rod rethreaded, "needle cushion" cut off & new seals(metric, shipped in) installed for a tad over $600. Money VERY well spent as it works better than when new.
SNIP
Sorry don't have any serial #'s handy but it is a 2009 model year. If for any reason someone wants them can put up later.

CG, that's real interesting - thanks for doing that post. It matches what I heard from the Kubota rep which was that the nut that holds the piston to the rod hadn't been locked down properly when the cylinder was originally assembled. So eventually it would back off the threads and jam against the bottom of the cylinder - shortening the stroke so that the main boom wouldn't raise up enough to engage the travel lock claw. That sounds like exactly what your rebuilder found.

If so, that's a bit scary because it means as the nut backs off the BH is going to continue to work normally except the boom can't be locked to travel - which is OK until that nut finally works it's way completely off the cylinder rod and the whole boom falls without warning. I remember that we continued to use mine for a week or so before calling the dealer to describe the problem, and then continued to use it until the new cylinder came and was installed. Being pretty sure what was going on, we were careful not to let anyone get under it in case it suddenly failed.

I hope that anyone with any backhoe that has either boom cylinder not fully closing will take a moment to think about the consequences of a failure there. In fact, that's a lot of why I'm writing this post today.

It surprised me when Kubota replaced the whole cylinder on mine instead of rebuilding it. Given the failure mode, a repair at a competent hydraulic shop along with some re-machining ought to be a decent repair. Seems odd to scrap the whole part. Although thinking about liability..... maybe not. When I asked, the Kubota mechanic said what he heard was that the BH cylinders had been outsourced, were not of Kubota manufacture, and the cylinder manufacturer was eating the cost. Maybe-so; it does make a kind of sense.
rScotty

 

[dstallman]

CG, that's real interesting - thanks for doing that post. It matches what I heard from the Kubota rep which was that the nut that holds the piston to the rod hadn't been locked down properly when the cylinder was originally assembled. So eventually it would back off the threads and jam against the bottom of the cylinder - shortening the stroke so that the main boom wouldn't raise up enough to engage the travel lock claw. That sounds like exactly what your rebuilder found.

If so, that's a bit scary because it means as the nut backs off the BH is going to continue to work normally except the boom can't be locked to travel - which is OK until that nut finally works it's way completely off the cylinder rod and the whole boom falls without warning. I remember that we continued to use mine for a week or so before calling the dealer to describe the problem, and then continued to use it until the new cylinder came and was installed. Being pretty sure what was going on, we were careful not to let anyone get under it in case it suddenly failed.

I hope that anyone with any backhoe that has either boom cylinder not fully closing will take a moment to think about the consequences of a failure there. In fact, that's a lot of why I'm writing this post today.

It surprised me when Kubota replaced the whole cylinder on mine instead of rebuilding it. Given the failure mode, a repair at a competent hydraulic shop along with some re-machining ought to be a decent repair. Seems odd to scrap the whole part. Although thinking about liability..... maybe not. When I asked, the Kubota mechanic said what he heard was that the BH cylinders had been outsourced, were not of Kubota manufacture, and the cylinder manufacturer was eating the cost. Maybe-so; it does make a kind of sense.
rScotty

I just bought a 2008 M59 from Ginops in Michigan, 1400 hours. Seemed to be in good shape. Sales staff were very nice. I noticed the boom would not retract all the way to the transport position so the transport hook would engage it. I asked sales staff and their Kubota mechanic about it and no one seemed to know what caused this. I bought the tractor thinking there must be some adjustment as JD has on their backhoes. Disappointed in their apparent lack of knowledge but happy I found the apparent cause here. The hoe seems to work fine otherwise and it seems to be short of latching on the hook by only a few mm.

 

[rScotty]

Congratulations on the new tractor! I'm sure you will like it; you hear very little negative on this model...and a whole lot of good. We simply think ours is just about the best purchase we ever made. It's a keeper. Runs like a top.

At 1000 hours, just routine maintenance plus one cable and two hoses - and that cylinder.

Regarding the boom cylinder, yours sounds just like mine. When it wouldn't retract all the way it sure looked like an adjustment or minor repair was all that was needed. As you say it only missed closing by just a few mm. But apparently that was the rod nut backing off - and the next thing would have been the boom falling. Obviously defective manufacture (and design), so it was the subject of a recall by Kubota at one time. My own M59 was out of warranty, but the dealer was very prompt about replacing the entire cylinder with an upgraded part. When I asked him about it, he showed me the "top issues" bulletin with I'm copying for you below.

I'd guess that for safety issues this obvious they didn't want the liability. But I wonder why they didn't replace all the cylinders in all the 2008 models? Kubota certainly know who the owners were - it was a brand new model and there weren't that many of us. Wouldn't you like to have listened in to their boardroom discussion!

Anyway, it's a known safety issue and a serious one. So you either ought to get the new part via the bulletin below.... or have your local hydraulics shop fix yours. And be very careful until then - there won't be any warning if it lets go.

That's been the sole downside to the M59, and as I said - Kubota was apparently very quick to fix the cylinders that they knew about. It's been long enough ago (about 2011) that it's not surprising a dealer wouldn't remember.
rScotty