So my b20 that I have brought back from the dead almost acts like it is starving for fluid in the loader and hst. I can see the hose lightly bounce on the loader control and when I am driving around it almost feels like it runs out of fluid and then gets some again and takes back off. I have plenty of strength in the HST. I dug into some serious material and pushed right in the other day. It just kind of surges at times. When I replaced the rear axle seals earlier(which was quite a job for axle seals) there was some odd sludge in the rear axle. It almost acted like crazy polymer or something you could pull it for miles. Well I cleaned it all out and I have probably only operated this tractor 20 hours and in that time I have drained the fluid(all the drain plugs opened) 3x and changed the filters 3x. When looking through the manual it shows how to test the pressures and relief valve and references a tool. I was wondering if anyone has the tool kit and could loan it or maybe just take pictures and provide specs and I could make my own. 07916-52040 is for the kit and the adapter set is 07916-53072. The manual shows it might be the relief valves.
B20 HST acting odd looking in manual anyone have a kubota hst tool kit?
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North Idaho Wolfman
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If you are having a loader and HST issue, it's not the HST relief valves causing the issue.
Does the streering also act up when it's doing this?
It's very likely a suction line issue:
The small pump also supplies the HST charge pressure, so if it gets air the HST is affected.
Does the streering also act up when it's doing this?
It's very likely a suction line issue:
The small pump also supplies the HST charge pressure, so if it gets air the HST is affected.
I second Wolfman's advice. It sounds like your implement pump(s) are not delivering full flow. Thats where you should focus your immediate attention. It could be a suction side problem and/or a pump problem
Dan
I have replaced all of the suction side seals except 90 and 60 in that diagram(they are on order with some other bits from messicks). The steering acts fine.
My loader seems to work fine. Like I said in the original post the line jumps a bit which means it might have air in it. I had already ordered the parts to finish replacing the suction side but they haven't shipped yet. I was hoping someone had the kit. I would like to check my hydro pressures at some point.
If the HST is working thats a waste of time. The HST is its own circuit and has ZERO to do with the loader hoses or operating pressures.
If you want to test implement pump pressure buy a $15 3000 PSI hydraulic gauge, disconnect the supply hose from the loader valve, connect the hose to the gauge, and start the tractor. That will put the pump at full pressure so dont run the engine like that for too long.
Your tractor has an open center hydraulic system which purges itself of any air. The only way you can have air in that loader hose is if the pump is sucking air on the suction side.
Your HST works, the loader works, and it is perfectly normal for hydraulic hoses to jump when a valve is operated. I am still failing to see your problem.
Dan
North Idaho Wolfman
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That kit you listed ( which is $3000, so someone loaning it to you would be... well it isn't going to happen ) is for the HST relief valves which is much different than the Hydraulic relief valve.
If the HST is moving at all then it's not an HST relief valve issue.
As for the system pressures it's a little complicated on that model because of the mutiple pumps and mutiple hydraulic circuits and relief valves.
You have two pumps in addition to the HST pump which is internal to the transmission. The PS is fed off one them but I dont have documentation to say which or how.
Maybe I am having a senior moment. Please tell me what is not working and how?
Dan
My HST system is not working properly. That is why I was hoping to see what is in that HST tool kit so I could borrow or make one IF the suction oring and coupling hose doesn't fix my problem. If I am just driving the tractor normally(not pushing anything with the loader or anything in the loader...just driving fast) it sounds/feels like it is running out of fluid. It will slow down and then surge forward again. That said, we can close this thread. I will continue to work on it until it is fixed though. Thank you for the input.
The HST pump is inside the transmission and draws its fluid directly from the sump. There may be an HST filter and if so that is something to look at.
As far as testing HST pressures go I think all you need is some standard adapters for the test ports and gauges with the correct range. You will need the WSM for specifications and procedures.
Dan
North Idaho Wolfman
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That's not really true, this is one of the odd models that the HST charge pressure is from the main Hydraulic pump, so if that pump is sucking air then it will affect the Operation of the HST.
Thanks for the diagram. The source of charge pressure and oil was not clear from the online parts diagrams. A lot of other models use the PS return for charge oil so the B20 is not all that unique.
The HST motor and pump are a closed loop system. The primary source of HST pump inlet oil is the HST motor return oil. The charge oil is makeup oil for internal leakages in that closed loop. It also maintains standby pressure for operating solenoids and valves.. So yes loss of charge pressure/flow can cause his problems.
But that does not change my central point. He does not need that $3K toolkit to test HST pressures. All he needs for that is some fittings and gauges.
Dan
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Russell King
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Where and what is he supposed to test? I think it is probably the charge pressure but where does he tap into that system? I assume that is covered in the WSM but I am curious and don’t have the WSM to review.
Most of these transmissions have factory machined pressure test ports. The WSM has the locations, specifications and procedures. I would also have a hard look at the HST filter. It could easily interfere with delivery of charge oil.
Dan
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So I replaced the last 2 pieces of the suction system an oring going to the front crank driven pump and a coupling hose thing on that same line. Was still getting the surging. I decided just to test. I put some RTV around the hard line that goes into the pump(where I just replaced the oring) and let it sit 2 days. No more surging. Now I have a new issue. Not sure if it is related or not. I have a box blade on the back of my tractor and I went and used the loader for a while moving a bunch of dirt and mulch. Decided to level it out with the box blade and it went down and never game back up. BAH
Russell King
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I didn’t look all the way back to read all the posts so sorry about that.
If everything hydraulic is working properly EXCEPT the three point hitch valve that sounds like a piping or valve problem.
Check where the hydraulic block is (where all the hydraulic lines attach to the tractor itself) and see if there is some valve to set for when there are hydraulic accessories are added or not. Usually this is a large slot or a small lever that turns one way when tractor has nothing hydraulic attached and another position when something hydraulic (FEL,…) is attached.
If you have quick disconnects between the tractor and any add on hydraulic valve take them off and clean them and reconnect them.
Make sure the flow from the tractor is actually getting back to the tractor.
If everything hydraulic is working properly EXCEPT the three point hitch valve that sounds like a piping or valve problem.
Check where the hydraulic block is (where all the hydraulic lines attach to the tractor itself) and see if there is some valve to set for when there are hydraulic accessories are added or not. Usually this is a large slot or a small lever that turns one way when tractor has nothing hydraulic attached and another position when something hydraulic (FEL,…) is attached.
If you have quick disconnects between the tractor and any add on hydraulic valve take them off and clean them and reconnect them.
Make sure the flow from the tractor is actually getting back to the tractor.