Kubota b2150 HST not working

[Matoyan]

Looks like you've ruled out the clutch.

Does that mean it’s the HST?

 

[PoTreeBoy]

Does that mean it’s the HST?

First, I'm no expert on these things

Probably, but don't panic yet. There are some troubleshooting and repair steps that can be performed without removing and tearing into the trans.

There is a WorkShop Manual available online at KubotaBooks. Download it and study the Transmission section. It contains a troubleshooting diagram and some tests. Unfortunately, the tests require some special fittings.

I recommend performing those tests first. If you have a good dealer close, and they have the test kit on-hand, you may want them to perform those tests and report the results to you. Then you can, or have them, perform corrective action.

Like I said, I'm not expert on these things. Hopefully, one of the experts, or at least more experienced readers, will tune in here. Good luck.

 

[North Idaho Wolfman]

I noticed it has loader brackets and no loader.
If the hydraulic loop is not working properly that can affect the HST.

On to another test:
With the tractor running, move the three point lift lever, do the arms move up and down?
Same test while trying to move tractor. do the arms move up and down?
Do you get any difference in tractor movement when the three point is in operation?

 

[Matoyan]

I noticed it has loader brackets and no loader.
If the hydraulic loop is not working properly that can affect the HST.

On to another test:
With the tractor running, move the three point lift lever, do the arms move up and down?
Same test while trying to move tractor. do the arms move up and down?
Do you get any difference in tractor movement when the three point is in operation?

I’ll send a picture of the loop when I get home and run those tests.

 

[PoTreeBoy]

I’ll send a picture of the loop when I get home and run those tests.

I told you the expert would show up!

You said you cleaned the strainer. Looking at the diagram, I see two strainers, one for each pump. Did you clean them both?

 

[Matoyan]

I told you the expert would show up!

You said you cleaned the strainer. Looking at the diagram, I see two strainers, one for each pump. Did you clean them both?

2 strainers? Where? I only saw one in the WSM

 

[North Idaho Wolfman]

2 strainers? Where? I only saw one in the WSM

Maybe @PoTreeBoy was mistaken, as I only see one screen on that model.

 

[PoTreeBoy]

Maybe @PoTreeBoy was mistaken, as I only see one screen on that model.

Wolfman's right, of course. I was going to warn OP that the WSM covers several models, and there are some subtle differences. Then I fell into the trap, the figure below shows two strainers and a separate charge pump, but it's not for the 2150. The correct diagram also shows why the other hydraulics interact with the hydrostat.

 

[Matoyan]

I noticed it has loader brackets and no loader.
If the hydraulic loop is not working properly that can affect the HST.

On to another test:
With the tractor running, move the three point lift lever, do the arms move up and down?
Same test while trying to move tractor. do the arms move up and down?
Do you get any difference in tractor movement when the three point is in operation?

 

[Matoyan]

I took the loader off and the only logical place the hose connected to is the top female coupler.

 

[North Idaho Wolfman]

Yes that looped, Do the test with the three point because if that line is restricted or not moving fluid properly, that could be your issue.
The B2150 uses the main hydraulic pump to charge the HST and if it's not moving fluid properly the HST will act erratic.

 

[Matoyan]

I noticed that the 3-pt doesn’t go up or down. It “stuck” in the up position. The video shows in high speed but it does it in any of the speeds. You can hear the engine change pitch when you set it to up. I also turned the implement lower speed knob in both directions but no change.

High speed with 3-pt link

youtube.com

 

[Matoyan]

Yes that looped, Do the test with the three point because if that line is restricted or not moving fluid properly, that could be your issue.
The B2150 uses the main hydraulic pump to charge the HST and if it's not moving fluid properly the HST will act erratic.

I uploaded the video.

 

[Russell King]

You need some weight (sometimes) on the thee point arms to make it go down and the knob turned all the way towards the fast setting (assuming it is marked)

 

[Matoyan]

You need some weight (sometimes) on the thee point arms to make it go down and the knob turned all the way towards the fast setting (assuming it is marked)

I did that and the arms didn’t go down. I’ll try again tomorrow and add more than 45lbs

 

[Matoyan]

You need some weight (sometimes) on the thee point arms to make it go down and the knob turned all the way towards the fast setting (assuming it is marked)

the arms aren’t moving even after putting more weight on it and the knob twisted to fast. The tractor ran just like in the video posted.

 

[Matoyan]

Yes that looped, Do the test with the three point because if that line is restricted or not moving fluid properly, that could be your issue.
The B2150 uses the main hydraulic pump to charge the HST and if it's not moving fluid properly the HST will act erratic.

I got the three point to go up and down. If the tractor is moving, when I move the 3-pt up, the tractor stops until it’s all the way up and the tractor moves again. 3-pt going down doesn’t seem to make that much of a difference. On medium speed, the tractor moves only on flat paved surface. On high speed, the tractor moves at times but only in the garage on flat concrete floor. This is frustrating!

 

[PoTreeBoy]

I got the three point to go up and down. If the tractor is moving, when I move the 3-pt up, the tractor stops until it’s all the way up and the tractor moves again. 3-pt going down doesn’t seem to make that much of a difference. On medium speed, the tractor moves only on flat paved surface. On high speed, the tractor moves at times but only in the garage on flat concrete floor. This is frustrating!

When the tractor stops, does the power steering also quit working (assuming you have power steering)?

That sounds like the priority valve isn't working right. I've included the hydraulic flow diagram for your B2150HST, and I must say it's one of the most complex.

Inside the hydraulic block 4, is the priority valve 24. Its function is to route the first flow (higher priority) of a certain amount to the power steering and on to the hydrostat charge. The remainder is available for loader, 3ph, etc. If the priority valve isn't functioning, the flow can take the path of least resistance which apparently is the unloaded 3ph. The power steering and hydrostat are in series; that's why I asked if PS also quits

The priority valve consists of a spring loaded plunger and restriction orifice. Maybe it's propped open with debris or the spring broke. The WSM shows the hydraulic block, but it uses the same figure for the models with and without the priority valve, so it's confusing to me. Hopefully, by looking at your block and comparing it to the WSM, you can remove the priority plunger and clean and check it.

Edit: I didn't mean to jump in Wolfman's way. Reading back, I see he had OP working in logical steps. He probably has a better plan.

 

[Matoyan]

When the tractor stops, does the power steering also quit working (assuming you have power steering)?

That sounds like the priority valve isn't working right. I've included the hydraulic flow diagram for your B2150HST, and I must say it's one of the most complex.
View attachment 153219
Inside the hydraulic block 4, is the priority valve 24. Its function is to route the first flow (higher priority) of a certain amount to the power steering and on to the hydrostat charge. The remainder is available for loader, 3ph, etc. If the priority valve isn't functioning, the flow can take the path of least resistance which apparently is the unloaded 3ph. The power steering and hydrostat are in series; that's why I asked if PS also quits

The priority valve consists of a spring loaded plunger and restriction orifice. Maybe it's propped open with debris or the spring broke. The WSM shows the hydraulic block, but it uses the same figure for the models with and without the priority valve, so it's confusing to me. Hopefully, by looking at your block and comparing it to the WSM, you can remove the priority plunger and clean and check it.

Edit: I didn't mean to jump in Wolfman's way. Reading back, I see he had OP working in logical steps. He probably has a better plan.

does the flow priority valve just unscrew?

 

[Matoyan]

it unscrews according to the WSM.