B1700 hst Transmission power loss

Razpool

New member

Equipment
B1700Ht
Sep 29, 2010
2
0
0
Orgiva, Granada, Spain
Hi there all! I have a serious problem with my B1700 HST

It is not a new machine but has given many years service.

I suspect my problem is self inflicted through stupidity.

At a job I caught a hydraulic line and lost a lot of fluid. I HAD to get the machine home because I HAD to do anther job the next morning so I topped up with some used engine oil from my Jeep. I keep the Jeep oil very clean so it was only six months old and a bit sooty. Yep Dumb but it got me home where I drained all the oil, fixed the leak, topped up with new oil and forgot the whole thing. Some weeks later the machine was very reluctant to move one morning. It had been fine the day before, but now it acted like it had no trans fluid in it.
When I checked there was oil . BUT I remembered the dirty stuff I had put in , so I checked the cartridge filter and sure enough it was black inside so I washed it with petrol and put it back and things were better but not best.
I spoke to KUBOTA who said that a bit of dirt in the filter would not affect anything as it was on a return line, and that as I had an old machine the charge pump was probably worn. (By carbon in the oil?) This sounded OK apart from the fact that the machine went wrong over night. Literally. Now some months later it is still the same. It goes, it moves, but high ratio is a no no except on level ground, and in low the machine won't climb well. It goes up some quite steep slopes, but it used to climb things that were more or less vertical if it could get grip. Now if baulked by a steep slope it "groans" and shudders and stops. It does not roll back. If I do a lot of work and get it good and hot the problem worsens.

I need to find out how to diagnose this. It should be noted that I live in the south of Spain where there are NO service facilities. so I do all my own work and I'll be fixing this too. Thing is I don't want to split the machine to reach the pump ifI don't need to.

I have a new cartridge filter on order (been to poor to buy one up to now) and I have been wondering if a blocked filter could be causing the pressure in the HST to get so high that it is opening the release valves and reducing the power. We will see. My German mechanic friend favours release valve trouble.

So any ideas ? Any one familiar with the procedure for getting at the relevant areas ? Can the charge pump be reached without splitting the machine ? How about the release valves. I have had to replace the loader/lift pump's release valve so they DO wear ?Any help and advice would be great, but as I said It is almost certainly my fault that I have a problem at all. It should be noted that the problem is not getting worse. The machine went from good to bad over night and has not worsened since. The PTO still gives full power , but then then I think that it has a shaft that passes the HST/Pump combo. I have the parts PDF but I would LOVE the workshop manuel.

Go well all. Raz
 

eserv

Well-known member

Equipment
BX24, A1000 Kubota Generator
May 27, 2009
2,101
93
48
Hardisty, Alberta
Hi! Bad luck with your Bota!
I suspect the damage was done when you initially ran it low or out of oil. The HST has two brass valve plates in it which are very fussy about having an oil film on them. one or two gulps of air and they are toast! There are no clutch packs in any Kubota HST. There is a variable displacement axial type piston pump which you control with the HST pedal, and a fixed displacement axial type piston motor that drives the machine. each of these two components have a valve plate that is likely damaged ( along with the companion face of that rotary group, pump or motor) The hst also has a charge pump whose job it is to keep the hst full of oil and circulate the oil through the cooler. The Kubota HST is very easy to work on! very few dealers will repair one though, to them it is simple a miraculous that they work at all and because they won't take the time to figure out how it works they are afraid to work on them. You probably could easily repair it yourself if you have the facilities to tear it down and reassemble it. The key to successfully repairing ANY hydraulic components is absolute cleanliness! and especially HST units.
If you take it to MOST dealerships you will come away with at least a $3000 dollar bill:eek: Good Luck!
Ed
 
Last edited:

kuboman

Member
Dec 6, 2009
725
1
16
Canada
Hi! Bad luck with your Bota!
I suspect the damage was done when you initially ran it low or out of oil. The HST has two brass valve plates in it which are very fussy about having an oil film on them. one or two gulps of air and they are toast! There are no clutch packs in any Kubota HST. There is a variable displacement axial type piston pump which you control with the HST pedal, and a fixed displacement axial type piston motor that drives the machine. each of these two components have a valve plate that is likely damaged ( along with the companion face of that rotary group, pump or motor) The hst also has a charge pump whose job it is to keep the hst full of oil and circulate the oil through the cooler. The Kubota HST is very easy to work on! very few dealers will repair one though, to them it is simple a miraculous that they work at all and because they won't take the time to figure out how it works they are afraid to work on them. You probably could easily repair it yourself if you have the facilities to tear it down and reassemble it. The key to successfully repairing ANY hydraulic components is absolute cleanliness! and especially HST units.
If you take it to MOST dealerships you will come away with at least a $3000 dollar bill:eek: Good Luck!
Ed
If you take the hst unit out yourself there are lots of hydraulic shops that will overhaul it. I had a quote of around $1500 for a JD unit.
 

dusty-t

New member
Feb 17, 2009
974
2
0
Mountforest Ontario
We have all done it Vic. I am personally terrified of the hydrostat. Thats why I really would like to get my hands on something like that to rebuild. As long as it doesn't cost me $5000 to face my fear.From what I have seen in diagrams and such they don't seem that complicated. Razpool keep us posted and don't give up on it.:D Dusty
 
Last edited:

kuboman

Member
Dec 6, 2009
725
1
16
Canada
Hydro trannys are really butt simple. The biggest things is cleanliness as they run on machined tolerances so any dirt will cause damage. The hardest part is getting them onto the work bench.:D
 

morris9460

New member

Equipment
B2400 La351, Yanmar 1110d, 4'rear mower, 50 gal. sprayer, tiller,rake,front plow
Aug 26, 2010
3
0
0
58
Elk River Mn
Hi am right in the middle of a hydrostat rebuild on my B2400 which is the bigger brother to your B1700. Right now I have the tractor split and am waiting for the parts that I ordered to arrive. Like what was said, it doesnt take much in a low or no fluid situation to burn up a hydrostat pump. I think a plugged filter could do it to, as well as high temperatures. Any abrasives or dirt in the fluid could prematurely wear one out too. Dealer wanted 2k to replace the hydrostat unit. Fortunately for me, I have split and repaired the tranny on my bx, so I wasnt afraid to tear into the B2400. With some online research, I was able to find a much cheaper parts source for hydrostat parts than from Kubota. So for Im into it for about $300, but that could change.
 

Razpool

New member

Equipment
B1700Ht
Sep 29, 2010
2
0
0
Orgiva, Granada, Spain
FIRST THANKS GUYS ! Never got e mail notification for your replys so just looked toay.

OK so this looks doable (sp?) Got the new filter today. Machine better still, but not best.

Points to note. The Machine never ran dry.
It WAS used a lot after the oil change before it went sick.


Soooo I need to get at the HST /charge Pump assembly.

I have tools. Hydro Jacks. AND I can rig a hoist.

So firstly. It seems that as the machine will climb a 30º slope things are not too bad, ie nothing has snapped. BUT am I right in assuming that as the machines tries to climb / Push / pull HARD the pressure in the HST system RISES ? I have an un wanted CLEARANCE some place and oil that should be pressing in the drive faces in the HST is escaping / by passing and causing this loss under load ? This clearance caused by a blockage / film of dirt OR component wear ? IE a release valve does not quite close ? OR opens too soon? The UK mechs that I have spoken to say that the HST unit is pretty much indestructible but that the charge pump will be to blame. We'll see huh ?

Secondly. The route in. How to get at the components.

I have a nice clean place to work so the HST holds no fear but I DO want to do the job right first time. Which leads to the question. "Can a workshop manual be downloaded from anywhere ?

Let me know. This is going to be fun.

Go well. Raz
 

bickle

New member

Equipment
99 b1700 hst 4wd
Oct 9, 2014
1
0
0
ontario
I have a 99 b1700 whos hyd pump has went as well, leaks when in high gear. they say I have to split the motor now is there a work shop manual you guys know of. And what is the cost for this repair? thanks only have 1300hrs on this tractor.
 

North Idaho Wolfman

Moderator
Staff member
Lifetime Member

Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
23,133
1,227
113
Sandpoint, ID
I have a 99 b1700 whos hyd pump has went as well, leaks when in high gear. they say I have to split the motor now is there a work shop manual you guys know of. And what is the cost for this repair? thanks only have 1300hrs on this tractor.
Don't confuse the Hydraulic pump and the HST unit as the same thing, they are two different parts that do two different jobs.

Sadly, does not look like there is a wsm manual free download to be had for the b1700.
Next best bet is to buy one.
P/N 97897-11776 $78.12
http://www.colemanequip.com/Parts_Detail.asp?partID=19467
 

cb750k8

Member

Equipment
B7200HST D 4X4
Aug 23, 2013
99
1
8
Dublin, Ireland
Hi
You have a problem but may be it is not as big as it now seems.
First thing is to go to "kubotabooks.com" and the B1700 is there. Find the manual that is for your tractor.

Please be aware that Kubota may not have manufactured the HST and it may
be covered elsewhere.

The HST for my tractor is quite well covered. B7200 HST in that manual and yours looks very similar.

Next thing is to equip yourself with a proper gauge and hose and do the testing on all test points before you take down the tractor. The problem could be relief valves and settings and if/when you take the tractor down and look at all the components you may not be able to "see" a damaged component because tolerances are so fine. Pressures at various settings of RPM should be what the manual says. This testing will point at what may be going wrong.

If you decide the tractor should be split then the usual applies. Clean workshop, photograph everything as you dismantle, boxes for components etc.

I have downloaded these manuals in Dublin and dont see why you could not download them in Spain. A printout would be recommended otherwise your computer will become "lubricated".

Like you, I was suspicious and afraid of the HST when I did a restore. Did this testing. Found all pressures to be OK, and now I am happy with it.

Hasta la Vista.
 

North Idaho Wolfman

Moderator
Staff member
Lifetime Member

Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
23,133
1,227
113
Sandpoint, ID
First thing is to go to "kubotabooks.com" and the B1700 is there. Find the manual that is for your tractor.

I have downloaded these manuals in Dublin and dont see why you could not download them in Spain.
Double check, there is no WSM manual for the b1700 on Kubotabooks.com, and a B1700 is not close to a b7200. ;)
 

cb750k8

Member

Equipment
B7200HST D 4X4
Aug 23, 2013
99
1
8
Dublin, Ireland
Hi
Wolfman is quite correct. You would be advised to have the appropriate WSM available before a teardown.

The proper workshop manual will advise test and service procedures.

The parts manual Page 58 on "kubotabooks.com" shows a breakdown of the HST system for your tractor.

My Point being made is that with a pressure gauge and before the teardown you could gather valuable information. You will need to understand the HST system and a pressure gauge, is needed in any case after reassembly, to confirm your system is up to spec.

Keep in touch and you will get valuable help from this site
Cheers