Kubota B20 loader/hydrostat not working!

johneking · May 27, 2015

While doing some bush hogging last fall I experienced a weakness in my front end loader, bush hog up/down and forward/reverse from the hydrostatic transmission.
I have removed/cleaned/inspected the "front" pump {drives off the crankshaft} gone through the "block" {found a stuck "diverter valve" and cleaned it} have tried just about everything including bleeding of almost all fittings {thinking I got air in the system} replaced all hyd oil and filters, checked all connections. No bubbles in oil and all fittings when loosened while tractor at 2,000 RPM's produced quite a bit of hyd. oil and few if any bubbles.
Now the loader only works when the "quick connector" on the rear {the one used for the back hoe/post hole digger etc.} is disconnected - up/curl/dump only but will only go down when "quick connector" is plugged back in - which I assume is relieving oil and allowing it to lower.
I have owned this tractor since 1995 {had 1600 hrs} and have had absolutely no trouble out of it until now with 2,650 hrs.
I now have the "Control Valve" {operates the bush hog/3 point hitch lift arms} off and plan on taking it apart to see if a check valve is stuck.
After removing the "front" pump and replacing, I now have no transmission and have experienced the loader issues.
Any help/ideas would be greatly appreciated as I don't want to pay a Kubota dealer to "parts replace" until they find the problem while they smoke cigarettes, drink cokes and tell jokes to the tune of $100/hour!

johneking · Jun 25, 2015

Since I got zero help from anyone, I thought I would follow-up and finish this article.
I finally bought a new hydraulic pump {$550!!!} replaced the "quick connector" on the left rear side under the seat [$45.00} removed/cleaned/replaced the "Control Valve" {controls the lift for rear attachments [bush hog, post hole digger, box blade etc]} replaced all rubber hose connections in "suction/supply" hydraulic lines -- NOTHING WOKED STILL!!!
Removed both "pressure relief valves" from the right and left sides of the transmission, dis-assembled them, cleaned and replaced -- no change!
I made 4 trips to the local Kubota dealership and talked with two "knowledgeable" mechanics, contacted Kubota Int'l in Fort Worth, TX -- no help from anyone! They all said check this/check that/do this/do that -- all bullcrap!
Now, got the hydrostat foot pedal hooked back up {the bolt/lock washer had fallen off the back side allowing the linkage to drop down} which would now let the trans. move the tractor -- nothing!
Finally flipped the "Diverter/Hydraulic Block" shut-off {it was marked to show open as horizontal} to the vertical position and all started working!!!!!!!!! Loader, hydro stat, bush hog raise/lower -- EVERYTHING!
I was elated to say the least!
Moved the tractor onto the concrete drive to be able to adjust the bush hog as all adjustments had been moved, shut tractor off and got the necessary tools to do so. Started the tractor back up {motor works GREAT} and the bush hog would not raise, loader shook like **** while trying to raise and hydrostat trans, was extremely weak. WTF NOW????!!!
The bush hog control {Control Valve -- that's right, that's what it's called} has an adjustable rod on it called the "Rod, Feed Back" and it's job is to relieve the hydraulic pressure once the lift has reached maximum setting {which is adjustable} and IF it is out of adjustment, nothing will work!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
I disconnected "Rod, Feed Back} and worked the lever by hand while leaving the control lever in the "up" position and guess what -- loader, bush hog, hydrostat -- EVERYTHING WORKED CORRECTLY!!!!!!!!!!
It is a fairly sensitive adjustment and if not set correctly, all hydraulic fluid will "by-pass" and not create enough pressure to accomplish jack squat.
I was then able to adjust the bush hog to my preferred settings, grease all fittings, replace the grill and hood, check tire pressures and put the tractor to work.
I ran it almost continually yesterday for 7 hours with absolutely no problems in 94 degree temps hogging 12' to 15' grass/weeds/trees etc.
Today the motor oil is down about 1/8th inch as well as the hydraulic oil -- which has always been the case under those conditions.
So, after almost $800 worth of "stuff" {that probably was not necessary!!!} I found an adjustment that the main mechanic at the local dealer replied "yeah, that will for sure do that if it's out of adjustment" -- AFTER I called to let him know what I had found! "YEAH, THAT WILL FOR SURE DO THAT IF IT'S OUT OF ADJUSTMENT"!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Kubota mechanics/tech support/etc -- probably like JD, IH etc.
Good luck to us all!!!

murphy1244 · Jun 25, 2015

johneking said:
Since I got zero help from anyone, I thought I would follow-up and finish this article.
I finally bought a new hydraulic pump {$550!!!} replaced the "quick connector" on the left rear side under the seat [$45.00} removed/cleaned/replaced the "Control Valve" {controls the lift for rear attachments [bush hog, post hole digger, box blade etc]} replaced all rubber hose connections in "suction/supply" hydraulic lines -- NOTHING WOKED STILL!!!
Removed both "pressure relief valves" from the right and left sides of the transmission, dis-assembled them, cleaned and replaced -- no change!
I made 4 trips to the local Kubota dealership and talked with two "knowledgeable" mechanics, contacted Kubota Int'l in Fort Worth, TX -- no help from anyone! They all said check this/check that/do this/do that -- all bullcrap!
Now, got the hydrostat foot pedal hooked back up {the bolt/lock washer had fallen off the back side allowing the linkage to drop down} which would now let the trans. move the tractor -- nothing!
Finally flipped the "Diverter/Hydraulic Block" shut-off {it was marked to show open as horizontal} to the vertical position and all started working!!!!!!!!! Loader, hydro stat, bush hog raise/lower -- EVERYTHING!
I was elated to say the least!
Moved the tractor onto the concrete drive to be able to adjust the bush hog as all adjustments had been moved, shut tractor off and got the necessary tools to do so. Started the tractor back up {motor works GREAT} and the bush hog would not raise, loader shook like **** while trying to raise and hydrostat trans, was extremely weak. WTF NOW????!!!
The bush hog control {Control Valve -- that's right, that's what it's called} has an adjustable rod on it called the "Rod, Feed Back" and it's job is to relieve the hydraulic pressure once the lift has reached maximum setting {which is adjustable} and IF it is out of adjustment, nothing will work!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
I disconnected "Rod, Feed Back} and worked the lever by hand while leaving the control lever in the "up" position and guess what -- loader, bush hog, hydrostat -- EVERYTHING WORKED CORRECTLY!!!!!!!!!!
It is a fairly sensitive adjustment and if not set correctly, all hydraulic fluid will "by-pass" and not create enough pressure to accomplish jack squat.
I was then able to adjust the bush hog to my preferred settings, grease all fittings, replace the grill and hood, check tire pressures and put the tractor to work.
I ran it almost continually yesterday for 7 hours with absolutely no problems in 94 degree temps hogging 12' to 15' grass/weeds/trees etc.
Today the motor oil is down about 1/8th inch as well as the hydraulic oil -- which has always been the case under those conditions.
So, after almost $800 worth of "stuff" {that probably was not necessary!!!} I found an adjustment that the main mechanic at the local dealer replied "yeah, that will for sure do that if it's out of adjustment" -- AFTER I called to let him know what I had found! "YEAH, THAT WILL FOR SURE DO THAT IF IT'S OUT OF ADJUSTMENT"!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Kubota mechanics/tech support/etc -- probably like JD, IH etc.
Good luck to us all!!!

Well at least you fixed it. Good job!

downsizingnow48 · Jun 25, 2015

I didn't have any ideas to offer, thx for posting the fix.

johneking · Jun 25, 2015

Maybe it will help someone else as I spent HOURS on it!!!
In hindsight, maybe it would have been better to take it to the dealer and their mechanics but as you can see, I didn't have a lot of luck with them from the beginning and feel like $800+ might just be cheap compared to what they would have "changed" and said I needed before they finally found the problem.

David_Kb7uns · Jun 25, 2015

My old Massey MF35 has draft control, many of the newer utility tractors do not have the draft control and a few out there you can get it as an option, so diagnosing draft control/ 3pt problems is not always a strong thing here.

David