HST repair on B1750

[captfrank]

Well… I’ve messed up. I spent two years rehabbing (slowly along with my job and other activities) my Kubota 1750 HST. It is 30+ years old and has 2800 hours and I have mainly used it for loader work and mowing (For the past 15 years, a helper did all the mowing on it and really beat it up). In the past two years I’ve replaced the radiator, starter, engine rear main seal, all front drive seals and gaskets, universal joint, clutch, pilot bearing, throw out bearing, repaired some sheet metal and a lot of other items.

So, I finally fired it up and let it run in place for about 30 minutes. Oops… There was very little hydraulic oil in the HST. After correcting that, now it won’t drive. Starts easily, runs well, but pressing the foot pedal either kills the engine or creates lots of noise. At one point, pressing the pedal forward drove the tractor in reverse and pressing the pedal in reverse drove the tractor forward. No movement now, just killing the engine or lots of noise when I press the foot pedal. It is apparent the HST is really messed up.

Three-point lift and power steering operating fine. Going to go to other projects but will get back to this in the near future. Have the repair manuals but am leery of the repair process on the HST unit. But will have to dive in at some point.

Anybody done a repair on the HST on a B1750 and what advice can you give?

 

[North Idaho Wolfman]

Well… I’ve messed up. I spent two years rehabbing (slowly along with my job and other activities) my Kubota 1750 HST. It is 30+ years old and has 2800 hours and I have mainly used it for loader work and mowing (For the past 15 years, a helper did all the mowing on it and really beat it up). In the past two years I’ve replaced the radiator, starter, engine rear main seal, all front drive seals and gaskets, universal joint, clutch, pilot bearing, throw out bearing, repaired some sheet metal and a lot of other items.

So, I finally fired it up and let it run in place for about 30 minutes. Oops… There was very little hydraulic oil in the HST. After correcting that, now it won’t drive. Starts easily, runs well, but pressing the foot pedal either kills the engine or creates lots of noise. At one point, pressing the pedal forward drove the tractor in reverse and pressing the pedal in reverse drove the tractor forward. No movement now, just killing the engine or lots of noise when I press the foot pedal. It is apparent the HST is really messed up.

Three-point lift and power steering operating fine. Going to go to other projects but will get back to this in the near future. Have the repair manuals but am leery of the repair process on the HST unit. But will have to dive in at some point.

Anybody done a repair on the HST on a B1750 and what advice can you give?

If you ran the HST with little or no Hydraulic fluid in it, I would bother with a rebuild, I'd be finding a good used running HST.

Running it for 30 Min without fluid most assuredly will damage a whole host of parts, some of which you can not even buy any longer.

 

[rbargeron]

Sorry to hear about this - especially after all the work you've done on it.

I agree with Wolfman - running an HST even for just a few minutes without everything inside being immersed in oil will quickly damage the many polished surfaces it relies on to function. Once they're scratched/scored replacing all of them is too expensive. Best to replace it with a whole functioning unit. Put on all new filters, flush out the cooler lines etc. and and change the filters, running it in neutral only for a few minutes on the first new filters - then drain and install new filters again.

The HST in the B1750 looks like the Kubota Type I version - but its part number 66415-11600 doesn't seem to cross to Kubota's Code 6C150-11603, the unit they now refer to as the Type I. Hopefully you can find one from an actual B1750. Take care, Dick B.

 

[Shadetree605]

Well… I’ve messed up. I spent two years rehabbing (slowly along with my job and other activities) my Kubota 1750 HST. It is 30+ years old and has 2800 hours and I have mainly used it for loader work and mowing (For the past 15 years, a helper did all the mowing on it and really beat it up). In the past two years I’ve replaced the radiator, starter, engine rear main seal, all front drive seals and gaskets, universal joint, clutch, pilot bearing, throw out bearing, repaired some sheet metal and a lot of other items.

So, I finally fired it up and let it run in place for about 30 minutes. Oops… There was very little hydraulic oil in the HST. After correcting that, now it won’t drive. Starts easily, runs well, but pressing the foot pedal either kills the engine or creates lots of noise. At one point, pressing the pedal forward drove the tractor in reverse and pressing the pedal in reverse drove the tractor forward. No movement now, just killing the engine or lots of noise when I press the foot pedal. It is apparent the HST is really messed up.

Three-point lift and power steering operating fine. Going to go to other projects but will get back to this in the near future. Have the repair manuals but am leery of the repair process on the HST unit. But will have to dive in at some point.

Anybody done a repair on the HST on a B1750 and what advice can you give?

hello, i do not, and have not worked on, or repaired your model ?, but i can say for a fact, i repaired my hydro on my b2100, 4wd version. i do not know if your version is close to my b2100hst, 4 wd ?, but if it is ?, it's not that hard to fix. the biggest issue you will run into is getting parts, and paying for them !..lol. most of the parts in the hydro tranny are not cheap at all !. but...when i compared the prices to fixing mine, or buying a refurb hydro ?, yeah.i went with fixing mine..lol. yes..the tractor will have to be split, so get ready to do some balancing with the front and rear sections.
Be ready to drain the hydro oil, as all of it needs to come out. then split the tractor. there are some lines that will need to be unbolted from both the front and rear in order to split the frame. its best to look online at messic's for a layout of all the hydro lines, and see where there are any oil seals ?, get them ready to swap out. spec around the front cover behind the clutch. fair warning !!! : there was a oil line that ran along, inside the frame where it bolts from the clutch cover to the back left rear side ( on mine anyway ), this line has o-rings at both ends, and you have to stab them blindly at the clutch cover, and back near the hydro system, what a royal pain this tube/line that was !. who ever thought this design up needs to be slapped !..lol. anyway..its not hard to do, just have plenty of time , and deep pockets if you plan on doing the work yourself ?. if i can do it ?, i see no reason why you can't. if ya was near me here in arkansas ?, i'd offer to help you free of charge, well..ok..maybe a cold beer after its done ?..lol.

 

[Mountainman]

If your interested in fixing it I have a good working hst unit from a 1750 in northeast Alabama. Just let me know if I can help. Thank you

 

[captfrank]

Well...I must be living right after all these years.
Ignored the Kubota 1750 for a week while I commiserated on my fate and searched for a used HSD. (Mountainman: Just now have visited the site and seen your post.) Later went out and on a whim started the Kubota up.
Pushed forward on the foot pedal. Went forward. Pushed back, went back. Drove out into the back yard. Ran great. Have used it for about an hour over the weekend. Did fine.
Will now finish a few items (adjust valves, clean injectors) and then reinstall the mower and use it lightly.
Thanks for all the support.
Shadetree605: I had previously split the tractor to install the rear seal, pilot bearing, clutch and throw out bearing. Wasn't too hard, except I stretched it out over too long a period of time.
Mountainman: I'll be emailing you if it breaks down.
https://natlcollegeedu-my.sharepoin...nts/IMG_3466 (1) (1).mov?csf=1&web=1&e=Q0fdqH
Frank

 

[Mountainman]

Well...I must be living right after all these years.
Ignored the Kubota 1750 for a week while I commiserated on my fate and searched for a used HSD. (Mountainman: Just now have visited the site and seen your post.) Later went out and on a whim started the Kubota up.
Pushed forward on the foot pedal. Went forward. Pushed back, went back. Drove out into the back yard. Ran great. Have used it for about an hour over the weekend. Did fine.
Will now finish a few items (adjust valves, clean injectors) and then reinstall the mower and use it lightly.
Thanks for all the support.
Shadetree605: I had previously split the tractor to install the rear seal, pilot bearing, clutch and throw out bearing. Wasn't too hard, except I stretched it out over too long a period of time.
Mountainman: I'll be emailing you if it breaks down.
https://natlcollegeedu-my.sharepoint.com//r/personal/flongaker_an_edu/Documents/IMG_3466 (1) (1).mov?csf=1&web=1&e=Q0fdqH
Frank

That's awesome man. Glad to hear it's working. I have a few 1550/1750 parts tractors here if you need anything.

 

[GreensvilleJay]

nice...
I know with riding mower HSTs (tufftork) there is a specific procedure to 'run them in'. Follow that and it works..... I think it has to do with purging the AIR out of the 'system' ,which of course runs on OIL....