hst problem

[jajsj]

I have a L3430 hst with 420 hours on it. It appears the hydrostat shelled out. The tractor doesn't move, and the filter and lines are full of different metals and maybe brass pieces. I am wondering if any one has had a problem like that? And if so, what did you do to get it fixed. Thanks, Jerry

 

[lugbolt]

Yes.

Replaced HST assembly. I eyed the possibility of rebuilding it but the HST internals were so worn, damaged, broken that it was more feasible to replace it as an assembly. It was not cheap though. I want to say $5500 but it's been a few years.

 

[jajsj]

I was afraid of that. Did you do it yourself or take it somewhere. Do you know if a transmission can be purchased from an after market place. Thanks for any information you can pass on. Jerry

 

[North Idaho Wolfman]

You won't find an "aftermarket transmission" that will fit.
If you call around you might find a good used one.

Shelled at 420 hours? Something doesn't sound right about that!

 

[lugbolt]

Jerry, I was working for a dealer at the time. That tractor, too, had lower hours, under 1000 as I recall. The owner told me that some of his crew had been operating with a dead battery, stopped the engine and couldn't get a truck to it to restart, so they pulled it back to the road somehow while it was still in low range. As I was told, it was at a pretty good clip too, which is probably what damaged it in the first place. Said they got it running and going again but it wasn't right. We got it in the shop and found lots of metal in the filters. Teardown revealed that even the housings were damaged, where the charge pump rides among many other places. It was a worst case scenario. Our service rep at the time had a look at it and said he'd never seen one or heard of one (nationwide) in that condition and didn't think that it was even possible.

The story we got may not have been the truth. The owner was told by his workers what happened, so you know how it is, could've been changed a time or two between worker #1 and whoever. We did notice that he was using some tractor supply hydraulic oil, and we looked at the bucket and it did not say it was UDT compatible. Don't know if that had anything to do with it or not. Also, the oil cooler was completely stopped up with dirt, which probably didn't help either.

Unlike cars, there isn't enough of a market for aftermarket companies to offer slow-moving parts for tractors, such as complete HST assemblies. You'll find aftermarket starters, dyamo's, alternators, maybe a water pump or two but that's about it. Faster moving parts.

 

[rentthis]

If you haven't done anything obvious to cause this damage, a call to your dealer is very much in order. The hydrostat in my L-45 bit the dust. It had many more hours but Kubota replaced it under warranty. If mine went out at 400 hours, I would be a wealth of conversation and accusation.

 

[rbargeron]

The number of failed Kubota HSTs is actually very small. This is good for almost all owners but can be expensive for the handful whose HSTs go bad. Many dealers have little experience diagnosing them - and for most fault symptoms the factory simply recommends replacement of the assembly.

Involving the dealer and a Kubota factory rep is a good idea. Depending on your machine's S/N there are three different part numbers, with the part price around $4600. Here's hoping that you get some help in this situation. Dick B

 

[zin01]

I have a question and instead of making a new post I thought I would just ask it on this one. Anyway my question is will it damage the HST any way when you hit reverse while still moving forward. For example when using the bucket it's slow but you scoop and hit reverse back up a little and then hit forward without stopping in between changing directions. My tractor is a B2650 if that helps


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[85Hokie]

I have a question and instead of making a new post I thought I would just ask it on this one. Anyway my question is will it damage the HST any way when you hit reverse while still moving forward. For example when using the bucket it's slow but you scoop and hit reverse back up a little and then hit forward without stopping in between changing directions. My tractor is a B2650 if that helps


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TO come to a complete stop is not necessary, however, I would not move from one to the other reaaal quick! It will do more damage to you and your load than it will the transmission.

What is really going on inside the HST is simple fluid flowing from one direction to another, the pressure throughout the system may ebb and flow, but as you ease off "forward" and then push on "reverse" the flow is stopping in one direction and simply flowing in another.

These machines were made to have someone drive them "like they stole them" and few of us with HST come to a complete stop before changing directions.

Again, the damage if moving too fast will be you in the seat!

 

[rbargeron]

Agreed - during abrupt direction changes the HST protects itself with its high-pressure relief valves. Momentary pressure spikes simply bleed off internally. It can still be jarring to the operator, so to help prevent steering wheel face plants there's a hydraulic damper that smooths out pressure surges from careless pedal motion.

 

[rentthis]

If the direction change doesn't hurt you, it won't hurt the tractor.

 

[lugbolt]

Another few ways to damage HST's in general, and it doesn't matter if it's a tractor, big tractor, little one, or lawn mower.

Lack of maintenance. Change the filters. Often.

Heat. Let the oil cooler get plugged externally and it'll damage the HST components. On BX's and a lot of the HST mowers, there is a fan that cools the HST-and that is ALL that cools the HST. Seen more than a few with broken and missing fans-this can cause them to get hotter than designed, and eventually fail. Once might not hurt it, or it might and then run for years before it completely dies. The early ZD21, ZD25, and ZD28 were known for HST failures, in part due to lack of maintenance.

Use of the incorrect oil. Super UDT2 only in "most" HST's. Not TSC's version (used for an example). I've had an HST in for repair, owner was using 90w in it-and it actually worked believe it or not, but not very well. The mowers sometimes use 20w50 engine oil, so be sure to refer to the WSM for your particular equipment.

Towing the machine without the main transmission being in neutral. Makes the rotating group(s) spin a LOT faster than they're designed to, and without the engine running, the charge pump isn't supplying lubricating and cooling oil to them while they're spinning at mach 3.6. On a lot of mowers, there isn't a neutral position so on those, don't tow them. They have a release lever but it's still not a good idea to tow-manually push by hand yes that's fine. That's all those levers are for anyway.

 

[rbargeron]

To get this thread back on track, finding a used HST is a bit of a long shot. When I read the original post I checked on a salvage L3830 listed at Mid-South Salvage - but they emailed back the HST was already sold.

Any total-loss Lxx30 tractor that arrives at a salvage yard is likely to still be "young", but the damage is quite severe (like a fire). There may not be a way to test a used unit except inspecting drained fluid. With asking prices for used around 50% of new, a brand new HST may seem a less risky alternative.

Sorry for the shortage of good news. Good luck - Dick B

 

[zin01]

Sorry for the off topic question and thank you to the op and everyone who answered my question.


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