b2150 hydrostatic replacement

rbargeron

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.....The one valve plate is still questionable, I might see about taking it to a machine shop to resurface it.........
I had PM'd Dave (dfkrug at TBN) and he replied that on his own he'd perhaps try resurfacing the valve plate before shelling out for a new one.

A finish resurfacing cut sounds good to me - I think the plate wants to be as flat and square-edged as possible. What holds the pump against the plate? Is plate thickness critical to operation? Would both need to be machined to preserve the stack-up?
 
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PW1967

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1993 kubota b2150hsd, fel, back hoe, log spliter
Aug 11, 2016
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colorado
I had PM'd Dave (dfkrug at TBN) and he replied that on his own he'd perhaps try resurfacing the valve plate before shelling out for a new one.

A finish resurfacing cut sounds good to me - I think the plate wants to be as flat and square-edged as possible. What holds the pump against the plate? Is plate thickness critical to operation? Would both need to be machined to preserve the stack-up?
took both plates to the local machine shop and he highly suggested not to resurface, being the fact that plate thickness is critical since the pump is in a fixed position against the plates, pump is held in the swash plate by retainer plate and snap ring. therefor machining just the bare minimum to clean up grooves could loose all sealing of the valve plates
 

rbargeron

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Good that you found that out before getting into a situation having to custom shim the assembly. Pretty soon there's no savings in rehabbing the old ones.
 

PW1967

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1993 kubota b2150hsd, fel, back hoe, log spliter
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working on reassembly, I got new gaskets, pin and some other stuff ordered from kubota, I decided to polish up the valve plates and hope for the best.

but first things first, I made a rookie mistake when splitting the tractor, I split it between the rear differential and transmission and separated the transmission case thinking it was all part of the hydro unit, and created myself a lot more work. After struggling getting the transmission case bolted and lined back up, being careful nothing was in a bind, the slider gear for the 4 wheel drive engagement is not working right. So I took the top cover off and used a long screwdriver against the slider rod and fork and the gear slides freely.

The hand lever will let me disengage it once its engaged, but it will not re-engage the gear back to the locked position. The hand lever seems to bind up before even attempting to move the slider in the transmission, Is this something the tractor has to be running to work, or am I overlooking something? I looked at the parts breakdown and everything looks in order, but I can not see whats going on inside the differential housing. I'm hoping I don't have to take the transmission case back off, anybody ever deal with this particular set up?
 

rbargeron

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Not experienced with this same model, but I'm wondering if (1) the fork 030 is correctly engaging the gear slot. Or if (2) the lever shaft 100 isn't engaging part 080.
 
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PW1967

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1993 kubota b2150hsd, fel, back hoe, log spliter
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Not experienced with this same model, but I'm wondering if (1) the fork 030 is correctly engaging the gear slot. Or if (2) the lever shaft 100 isn't engaging part 080.
I would assume the tab on shaft 100 should fit in 080, no way to see other than remove trans case,
 

PW1967

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1993 kubota b2150hsd, fel, back hoe, log spliter
Aug 11, 2016
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I got the tractor back together today, and no improvement on its performance, I am bummed, But at least I don't have a lot of money invested in the repair, yet, just a lot of time. So I guess I'll have to tear it back down again, but this time at least I know where to split it, at the bell housing, not the rear diff, that will save me hours of work.

I really don't want to throw a bunch of money to this thing and no garuntee that it's going to work right, now I know why a lot of shops don't want to rebuild them. Since I am pressed for time I think I will get on the phone tomorrow and see what I can find for a replacement and sent out here asap. So if anybody got any leads on one let me know.
 

rbargeron

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.........my hydro trans is in need of repair, slow and weak ground speed, and whining under load..........
Before you take it apart again, it might be useful to do operating pressure tests as described in the WSM. If forward and reverse are similarly lackluster in performance the problem could be in the charge pump or in the high-pressure check/relief valves. Not familiar with the B2150's HST but the larger ones have 5 relief valves in all - the two for high pressure, 2 more medium-pressure in the charge pump & filter circuit, and a 5th for gross HST case pressure - I believe all are accessible from the outside. You've already done more than many owners would tackle - it would be nice to prevail. We're pulling for you :)
 
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PW1967

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you are absolutely correct rbargeron, I already called the local kubota dealer, about a 100 miles away, and they said about two weeks out, they are swamped, but I will try a couple of closer shops, JD, and new holland are close by and I don't see why they could not do it, and if nothing else I can invest in some gauges and fittings and perform it myself.

and if I do this myself, any recommendations on a test gauge, looking in the WSM, they show a kit but looks kind of pricey,
 

rbargeron

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My experience is with the larger HST in an L48. The factory test setup covers a lot of models so its spendy. I got gauges from eBay and fittings from these guys. I got two pressure gauges 0-500 psi to test the charge circuit and two 0-7000 psi for the high-pressure circuits. Check you WSM to see what the pressures and procedures are for your model. The tapped holes in Kubota's HST are British Standard Pipe threads. I got adapter fittings for the gauges. JD dealers may or may not be set up for BSP threads.

If the performance (speed and torque) are similar in forward and reverse, it would point more to the charge pressure circuit. The high pressure valves are separate for F and R. If performance is different in F and R they can be swapped to see if the symptoms swap too. The charge circuit is common for both directions. Good luck - Dick B
 
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PW1967

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1993 kubota b2150hsd, fel, back hoe, log spliter
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Update: I was unable to get the correct fittings to tap into the hst for pressure test, so I dropped it off at a Kubota dealer 3 weeks ago and they just now got to it, and it aint good. The hst failed, along with the control valve for 3 point, and the charge pump is putting out a little over 5gpm, factory spec is around 7 gpm.

So I guess I need to figure out, Do I keep dumping money and parts into this or part the machine out. Their is about 4k in parts in the hst, and it probably going to need valve plates for about $750. but that may or may not be enough to fix it, even though the rest of the parts looked ok when I had it apart I did locate a used hst for $1700. and that might be a good way to go on that part.

What sucks is that the dealer want $800. for his services, he says he has 8 hrs into it, but I may have a fight on my hands over that one, That's totally ridiculous, should be able to do those test in a couple of hrs at most.

but anyway, it looks like I will be into this around 3k to get everything fixed, but I don't think I can replace the tractor for much more than that.
 

PW1967

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1993 kubota b2150hsd, fel, back hoe, log spliter
Aug 11, 2016
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Ok, I went and picked up tractor at dealer today, Service writer gave me a break and charged me 6 hrs. labor for pressure test, still alot but oh well it is what it is and I appreciate them doing it, I know how it goes in the shop, I am no stranger to this, as I deal with heavy equipment repair shops in my line of work, I'm just not the one who pays the bills. time is time, and time is money, but I thought I would post their test results here if anyone wants to chime in for any advise,
this is how stated on invoice:
charge pressure is 105 psi. and spec is 57 to 99 psi.
High pressure forward and reverse maxing out at about 380-390 psi. spec is 3983 to 4125 psi.

high pressure is 2000 psi. spec is 1920 to 1991 psi,

so this is when they called me the other day and told me the findings and thought the high pressure relief valves likely the cause.
they then further diagnosed and this is what they found (also stated on the invoice)
did more troubleshooting on unit since both high pressure valves failed. did a direct pump test, failed. with low initial gpm, spec is 7.4, its at 5, moved down the line to the flow divider, same result as direct test, moved down the line again, the 3 point control valve dropped to 4 gpm. when restriction was added it would drop to zero gpm, bypassed the flow divider and control valve directly from pump to hst, tested and pressure still not their

So with that, I'm sure the hst is dead, but do all the other components like charge pump, priority and control valve need replaced too? I understand hydraulics to a certain degree, but this little thing seems to get overly complicated for me. so any advise helpful thanks.

ok more I think about it, pumps create flow not pressure, restriction creates the pressure, so that would explain why I'm getting high pressure readings from charge pump, even though its low on the flow output. just cant figure out where I'm loosing it in the priority and control valves ?
 
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rbargeron

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From the test pressures posted I think the charge circuit (priority valve etc) may be ok. If the pressure tests were done right the issue is in the HST's internal pump/motor set.

Did you ever figure out why the dowel pin broke (Post #11) that registers the pump's seal plate to the housing? When I first read that I remember wondering what condition could put enough force on it to shear it.

Did you take any pics of the back ends of the pump & motor showing the surfaces that run on the valve plates? How did you clean up the gouged area around the failed pin?

Are the valve plates the same? Can they be mounted either way up? (sorry if dumb questions)

I'm betting you're going to solve this without spending big money. If the valve plates (and maybe the pump and motor housings) need to loose a few thousandths to be flat again, I'd do that and either shim the stack or machine the same amount off the housing so it goes back together right. With the contact surfaces trued up the oil film between them will then hold the pressure. Take care, Dick B
 
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PW1967

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1993 kubota b2150hsd, fel, back hoe, log spliter
Aug 11, 2016
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rbareron I tried to come up with the test fittings from the link you posted, but figured out Kubota uses a deep probe type fitting to test the hst as shown in the wsm. I was told that using standard size fittings would not provide a accurate reading so then I just decided to take it to the dealer for testing.
As far as the broken dowel pin, I think it was do to stress, and that was the weakest link. from starting in extreme cold and I think it had water in the system, not for sure but just speculating.
the valve plates are different between pump and motor, taking any material off the plates would loose all sealing capabilities, I don't see how you could shim the stack to make up the difference, I don't know, Ill enclose some pics maybe it will make more since to you.
I would just replace the valve plates, for about 700.00 but may not solve the issue, could be loosing pressure through the piston assymblys too.

Im just thinking a used hst that works may be the best option on that part.
 

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rbargeron

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Nothing jumps out at me in the pics. With the pump's locating pin reinstated I'd have expected it to work. Wonder if it's broken again? Something is preventing the pump from making pressure.

I'm not much help - the only HST I've worked on is pretty different. My issue was weak reverse but yours is both directions.

The test results the dealer wrote are hard for me to follow - they wouldn't make any sense for my HST because it has its own charge pump inside. Actually the fact that the testing dealer had to make a second attempt indicates they may not have much HST experience. I have found that HST knowledge in service departments can be low. HST's rarely fail so few ever work on them. The factory tends to recommend replacing the HST whole if basic function isn't right - they don't even want failed ones shipped back.

Does you WSM have troubleshooting on the priority valve, etc?
 
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PW1967

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1993 kubota b2150hsd, fel, back hoe, log spliter
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well shortly after my last post I got on the internet and called every tractor salvage yard in the country looking for a used hst, and not having much luck, then called an outfit in Riverdale, Ca. and he said no, but would put it on the hot line, then called me back 30 minutes later and said he found one in the LA area, so I purchased it vie credit card and had it shipped out here to Colorado and arrived on my door step this morning.

I am happy to report that I finally put the "mighty" back in "mighty mouse".
It took about 45 minutes to split it this time, since it was already partially dissembled, put the new to me pump on and pre filled it, and fired it up and babied it around a bit before going full bore, and it literately feels like it wants to climb a tree. I know you guys probably heard that expression before but that's what it feels like after running a tractor that's lost its mobility.

.

I also spit the old hst pump open, and everything still in tact but as little running time it had on it, the valve plates already had discoloring and burn marks, so I may take a crack at rebuilding it again when I can get over the pain and build up the funds again after spending 1700 bucks on this used one.

other than that, its off to other maintenance issues on this tractor and hopefully be done before the snow really sets in.
 

rbargeron

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Good outcome. Glad mighty mouse is running strong again.

The old hst is a head scratcher. They depend on a high level of accuracy and precision that's expensive to restore once disrupted. For the handful that fail, Kubota advocates junking them. Hard on the customer's checkbook, but maybe less pain overall. Good luck with the replacement - Dick B
 

glfinman

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I had the same problem of the hydraulic leaking bucket woulldn't stay up etc. I searched and searched and the control valve was out of stock. Dealer disassembled but it made only minor improvements. a Service mgr suggested that since it was a seldom used loader maybe a two handle system would work.
It does very well and the handles are close enough that I can operate with one hand simultaneously. But now the 3 point doesnt work. ?????
 

North Idaho Wolfman

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I had the same problem of the hydraulic leaking bucket woulldn't stay up etc. I searched and searched and the control valve was out of stock. Dealer disassembled but it made only minor improvements. a Service mgr suggested that since it was a seldom used loader maybe a two handle system would work.
It does very well and the handles are close enough that I can operate with one hand simultaneously. But now the 3 point doesnt work. ?????
Was there 2 lines or 3 lines off of the original valve (not including the 4 lines for the loader cylinders)?