Some of you may remember my Post about my B2601 breaking in half!

[torch]

Bubbles float. If you are seeing bubbles immediately from the output of the 3PH pump, then I really think the leak is in the suction for that pump. If the bubbles came from the hydrostatic pump, they'd float above the level of the intake for a while.

Conversely, if the 3ph pump is generating the bubbles, it will take a while to fill the sump with them, giving the hydro a few minutes of drive time before it starts eating air. That fits with your description.

Russel's suggestion would be a good confirmation. If you remove the 3ph pump and no bubbles appear in the sump, then it's gotta be the second pump. If they do appear, then it doesn't matter where you do or do not want to go.

 

[Egressman]

Can you remove or disable the external pump to isolate the problem?

Can you remove or disable the external pump to isolate the problem?

OK, guys!
Spent the evening trying to figure out if I could remove the external pump as suggested

Turns out the answer is yes, and no!

There is only one pump it has two circuits or sections inside it!

Number 5 on the drawing is for the 3Pt hitch only! Number 6 on the drawing is for the HST, power steering, and PTO!

I kept looking at the drawing and the flow, there were too many hoses coming out of the pump. It finally jumped off the page at me. There is no hidden pump inside the case unless I've lost my mind!

1 hose feeds the loader valve and then a line from the loader valve goes to the sump.

The second line goes to the steering and then to the PTO, and then to the HST! All through the cooler!

Review and tell me if I got it right.

All that being said, I'm really at a loss because fluid is flowing, It could be from just the point side of the pump. That would explain why everything else has failed but the 3pt still operates, even with aerated fluid.

What is my next step, do I pull the pump and look for issues, rebuild, or what?

The fluid is still getting air? I will look at the sump tomorrow to see if it's yellow again.

Do I have two problems, a bad pump and a leak in the suction side?

Going on 2am, my eyes are shot!

 

[PoTreeBoy]

OK, guys!
Spent the evening trying to figure out if I could remove the external pump as suggested

Turns out the answer is yes, and no!

There is only one pump it has two circuits or sections inside it!

Number 5 on the drawing is for the 3Pt hitch only! Number 6 on the drawing is for the HST, power steering, and PTO!

I kept looking at the drawing and the flow, there were too many hoses coming out of the pump. It finally jumped off the page at me. There is no hidden pump inside the case unless I've lost my mind!

1 hose feeds the loader valve and then a line from the loader valve goes to the sump.

The second line goes to the steering and then to the PTO, and then to the HST! All through the cooler!

Review and tell me if I got it right.

All that being said, I'm really at a loss because fluid is flowing, It could be from just the point side of the pump. That would explain why everything else has failed but the 3pt still operates, even with aerated fluid.

What is my next step, do I pull the pump and look for issues, rebuild, or what?

The fluid is still getting air? I will look at the sump tomorrow to see if it's yellow again.

Do I have two problems, a bad pump and a leak in the suction side?

Going on 2am, my eyes are shot!


View attachment 77922
View attachment 77916

Is it possible that the pump seal is leaking?

 

[Egressman]

Today the fluid is back to normal after it was full of air yesterday!

 

[Egressman]

Is it possible that the pump seal is leaking?

I think the pump has got to come off as a Minimum!

I did have a concern about the PTO control valve, it has an input line and it has three O-ring seal ports on the bottom that sends pressure or fluid to different places. I haven’t replace those O-rings and they look really flat so I’m going to replace those next.

I don’t know if sucking air at the PTO valve is the same as on the suction side but I can’t imagine introducing air anywhere is a good thing.

 

[Egressman]

These look like the only seals or gaskets! But the pump looks solid, paint still intact? Anything else to rebuild on it?

 

[torch]

OK, guys!
Spent the evening trying to figure out if I could remove the external pump as suggested

Turns out the answer is yes, and no!

There is only one pump it has two circuits or sections inside it!

Number 5 on the drawing is for the 3Pt hitch only! Number 6 on the drawing is for the HST, power steering, and PTO!

I kept looking at the drawing and the flow, there were too many hoses coming out of the pump. It finally jumped off the page at me. There is no hidden pump inside the case unless I've lost my mind!

1 hose feeds the loader valve and then a line from the loader valve goes to the sump.

The second line goes to the steering and then to the PTO, and then to the HST! All through the cooler!

I don't know anything about the B2601. That said, I would be very, very surprised if the HST is actually powered by an accessory hydraulic pump. That would be like driving the transmission of your car from the power steering pump. You want high-power requirements to be driven from the crankshaft.

Similarly, I would be very surprised if the PTO is powered from an accessory pump. I mean, it's right there in the name, the P in PTO stands for power. I could see a hydraulic clutch for the PTO perhaps, but not the PTO itself.

It does make sense for the power steering to have it's own dedicated circuit -- you don't want to lose steering when you use the FEL or lift the 3ph. A dedicated pump is one way to ensure that, the other is to use one big pump with a priority valve that ensures the steering circuit gets priority.

Also, I doubt the cooler is feeding anything. More likely it's on the suction side or at least on the return side. Thin metal facilitates cooling, but won't stand up to high pressures.

 

[Egressman]

I don't know anything about the B2601. That said, I would be very, very surprised if the HST is actually powered by an accessory hydraulic pump. That would be like driving the transmission of your car from the power steering pump. You want high-power requirements to be driven from the crankshaft.

Similarly, I would be very surprised if the PTO is powered from an accessory pump. I mean, it's right there in the name, the P in PTO stands for power. I could see a hydraulic clutch for the PTO perhaps, but not the PTO itself.

It does make sense for the power steering to have it's own dedicated circuit -- you don't want to lose steering when you use the FEL or lift the 3ph. A dedicated pump is one way to ensure that, the other is to use one big pump with a priority valve that ensures the steering circuit gets priority.

Also, I doubt the cooler is feeding anything. More likely it's on the suction side or at least on the return side. Thin metal facilitates cooling, but won't stand up to high pressures.

Not sure what you mean by "accessory pump?"

I'm just stating what the maintenance manual is showing.

One pump, located externally, has two circuits. One supports the 3pt hitch, the other side supports the power steering, then the cooler, then the PTO, then the filter, and then it goes to the HST!

You can see the flow in the drawings I attached. The suction side is simple, it has a filter, a pipe, a rubber hose, two hose clamps, and it goes from the sump to the pump.

The rest of the piping is a few tubes and some travel through the castings.

Am I missing something? Is my problem with the pump, or just a suction issue making the fluid worthless by allowing air to get in the system?

 

[torch]

B2601, right? I'm looking at the Kubota Canada parts finder website. There is a separate 7-cylinder variable displacement swash-plate driven HST pump inside the transmission.

The forward section of the exterior pump -- which I referred to as the "accessory" pump since it powers accessories -- supplies fluid first to the FEL, then from a PB port to the 3ph lift cylinder. From there it returns internally to the sump. (ignoring spool and relief valves).

The rear section of that pump supplies the power steering section. The return line from the power steering goes to the oil cooler (which IS more robust than I imagined). From the oil cooler, it goes to the PTO control valve. I assume this applies the PTO clutch (not the HST!) and returns to the sump internally.

Now, the suction side for that pump is where I suspect the problem lies. Fluid is supplied through the right hand rear axle housing to the oil filter housing. The two housings are sealed with a single O-ring and secured with a single bolt. From there it goes through the filter of course and then there is a single O-ring sealed pipe secured with a single bolt to the bottom of the housing. The other end of that pipe is secured to the pump by the rubber hose with a hose clamp at either end.

Leaks on the pressure side of the pump (including the PTO valve) will push fluid out when running. Leaks on the suction side can draw air in. I'd say your candidates are the o-ring between the filter housing and the axle housing, the filter seal, the o-ring on the pipe from the filter housing, either end of the rubber hose. Unlikely but possible are a cracked filter housing or cracked pump housing.

 

[Egressman]

B2601, right? I'm looking at the Kubota Canada parts finder website. There is a separate 7-cylinder variable displacement swash-plate driven HST pump inside the transmission.

The forward section of the exterior pump -- which I referred to as the "accessory" pump since it powers accessories -- supplies fluid first to the FEL, then from a PB port to the 3ph lift cylinder. From there it returns internally to the sump. (ignoring spool and relief valves).

The rear section of that pump supplies the power steering section. The return line from the power steering goes to the oil cooler (which IS more robust than I imagined). From the oil cooler, it goes to the PTO control valve. I assume this applies the PTO clutch (not the HST!) and returns to the sump internally.

Now, the suction side for that pump is where I suspect the problem lies. Fluid is supplied through the right hand rear axle housing to the oil filter housing. The two housings are sealed with a single O-ring and secured with a single bolt. From there it goes through the filter of course and then there is a single O-ring sealed pipe secured with a single bolt to the bottom of the housing. The other end of that pipe is secured to the pump by the rubber hose with a hose clamp at either end.

Leaks on the pressure side of the pump (including the PTO valve) will push fluid out when running. Leaks on the suction side can draw air in. I'd say your candidates are the o-ring between the filter housing and the axle housing, the filter seal, the o-ring on the pipe from the filter housing, and either end of the rubber hose. Unlikely but possible are cracked filter housing or cracked pump housing.

Now that I understand, I read about the squash plate and all that but I didn’t understand it.

I replaced the oil filter housing because it was cracked where the bolt connected the hose or pipe to the filter mount.

Everything you’re telling me sounds a whole lot easier than tearing the pump apart to not find anything wrong or actually creating another problem.

I will pull the suction tube and inspect it from end to end, I have new filters coming and I already have the o ring for the suction tube. I will pressure test both the rubber hose and the tube! The filter housing is new, the hole for the tube was broken so I replaced it.

I will update when I'm done, I really appreciate your help here.

 

[torch]

I replaced the oil filter housing because it was cracked where the bolt connected the hose or pipe to the filter mount.

Did you use new o-rings on both housing and pipe when you replaced the filter housing?

 

[hagrid]

Charge pump to fill the HST circuit.

 

[Egressman]

Did you use new o-rings on both housing and pipe when you replaced the filter housing?

Yes, Messicks loves me!
I was military, I worked on life support systems, you learn to not reuse parts like seals. It never saves you anything!

 

[torch]

Charge pump to fill the HST circuit.

Good point. I didn't see one listed in the parts diagrams. You don't suppose they are tapping into the feed for the PTO clutch to fill the HST pump, do you?

 

[Egressman]

Good point. I didn't see one listed in the parts diagrams. You don't suppose they are tapping into the feed for the PTO clutch to fill the HST pump, do you?

Yes, The PTO feeds the HST

4 is the pump, 1 is power steering, 2 is the PTO, and 3 is the HST.

 

[Egressman]

Yes, The PTO feeds the HST

4 is the pump, 1 is power steering, 2 is the PTO, and 3 is the HST.

View attachment 77994

Eating lunch then heading out to drain the system and remove the suction side line and check for leaks and replace all the seals!

 

[Egressman]

Well, Gentlemen!

I can't thank those of you that took the time to educate me enough! Without your help, I would be nowhere. Not only do I have a working 3 pt hitch, but I also have a working PTO, a working bucket, a working power steering, and movement both forward and aft.

I have all 3 ranges of power in the HST. The fix was small and those that said suction was the problem were 100% correct. I have attached some photos, the first is/was the problem!

Now I can start putting it back together and get back to tractoring!

 

[PoTreeBoy]

Well, Gentlemen!

I can't thank those of you that took the time to educate me enough! Without your help, I would be nowhere. Not only do I have a working 3 pt hitch, but I also have a working PTO, a working bucket, a working power string, and movement both forward and aft.

I have all 3 ranges of power in the HST. The fix was small and those that said suction was the problem were 100% correct. I have attached some photos, the first is/was the problem!

Now I can start putting it back together and get back to tractoring!

Thanks for the feedback. Glad you got it figured out.

 

[torch]

Eeeew, nasty. It even bent the bolt flange.

Glad you got it sorted finally. Happy tractoring!

 

[torch]

Yes, The PTO feeds the HST

4 is the pump, 1 is power steering, 2 is the PTO, and 3 is the HST.

Interesting. I suppose it is cheaper than a dedicated charge pump, but a little bit scary to think the HST is potentially run dry until the other systems are all filled. The factory probably uses some sort of assembly lube initially, but it's a good thing the OP didn't disconnect the external pump as a diagnostic!