B2150 / LA350 loader valve function diagnostic help please

[walkerheaders]

Hi guys, I know my Tractor and loader are obsolete. It's been a great machine since I purchased new in 1993. 2430 hrs later, An unusual thing happened in this last snow. I rolled toward the snow pile with the boom up and bucket dumping a load. The tractor slid into the snow pile with the bucket at full dump position. Not real hard or anything real unusual but.... at high rpm, the bucket did not want to curl back? It was moving to curl position very slowly and straining the pump. all other functions are normal. After a full curl back, at idle the bucket tilts forward and curls back smoothly. raise the rpm's and it strains to curl back again? I reversed the bucket lines and it seems to move smoothly. It's a but odd to see it operate in reverse and since the loader valve has the "speed dump" feature. (Regen?) Anyhow, today was nearly 40 degrees and I tee'd a 3000psi pressure gauge on the lower bucket cylinder hose. (the curl) and when straining to return I saw about 1600 psi. I then decided to swap the hoses on the valve right to left and let the boom spool power the bucket cylinders and the bucket spool power the boom. this worked fairly well but so backward. I actually loaded a bunch of snow this way and got the hang of it. The cylinders seemed to function normally leading me to believe the valve is at fault. when I returned home, I swapped the hoses back to normal and the trouble returned. At any rate, I understand that an aftermarket valve is in order and I need to decide regen or no regen (speed dump). I dont mind this swap but I really would like to know what went wrong all of a sudden? Hoses are new, fluid level correct and was changed about 100 hours ago. any idea what failed in the valve block? linkages are tight and spools move and detent as they should. strange one for sure. I would appreciate any insight. thanks so much.

 

[PoTreeBoy]

Paging @TheOldHokie. In the meantime, could you post a picture of the bottom of your valve? The end opposite where the spools come out. I've recently discovered that some Kubota loaders with regen have 3 positions and some have 4. This might help figure out your issue.

Does the boom circuit still function correctly? The way you described the occurrence, I'm inclined to suspect damage to the pivot or one or both cylinders, although some of the things you tried might not support this.

Can you confirm that the bucket can dump and curl easily with the cylinders disconnected? There may be a stop that got bent, but probably the cylinders limit the dump travel.

I'll stop here in case TOH has checked in.

 

[whitetiger]

Hi guys, I know my Tractor and loader are obsolete. It's been a great machine since I purchased new in 1993. 2430 hrs later, An unusual thing happened in this last snow. I rolled toward the snow pile with the boom up and bucket dumping a load. The tractor slid into the snow pile with the bucket at full dump position. Not real hard or anything real unusual but.... at high rpm, the bucket did not want to curl back? It was moving to curl position very slowly and straining the pump. all other functions are normal. After a full curl back, at idle the bucket tilts forward and curls back smoothly. raise the rpm's and it strains to curl back again? I reversed the bucket lines and it seems to move smoothly. It's a but odd to see it operate in reverse and since the loader valve has the "speed dump" feature. (Regen?) Anyhow, today was nearly 40 degrees and I tee'd a 3000psi pressure gauge on the lower bucket cylinder hose. (the curl) and when straining to return I saw about 1600 psi. I then decided to swap the hoses on the valve right to left and let the boom spool power the bucket cylinders and the bucket spool power the boom. this worked fairly well but so backward. I actually loaded a bunch of snow this way and got the hang of it. The cylinders seemed to function normally leading me to believe the valve is at fault. when I returned home, I swapped the hoses back to normal and the trouble returned. At any rate, I understand that an aftermarket valve is in order and I need to decide regen or no regen (speed dump). I dont mind this swap but I really would like to know what went wrong all of a sudden? Hoses are new, fluid level correct and was changed about 100 hours ago. any idea what failed in the valve block? linkages are tight and spools move and detent as they should. strange one for sure. I would appreciate any insight. thanks so much.

Replace the tips and couplers on your bucket hoses. You have at least one set that is not fully opening, which is restricting oil flow.

 

[PoTreeBoy]

Let's check the valve function.
Disconnect the hoses from both ends of one cylinder and put them in a bucket where you can observe the flow.
Start the tractor and run at idle. Push the lever to curl the bucket. You should get flow out of one hose. Push the lever to dump. You may get flow out of the other hose, or both hoses. If you have a 4 position valve you may get different behavior depending on whether you move the dump side a little or full stroke. If you have a 3 position valve, you should get flow out of both hoses.
Try this and let's go from here.

 

[TheOldHokie]

Hi guys, I know my Tractor and loader are obsolete. It's been a great machine since I purchased new in 1993. 2430 hrs later, An unusual thing happened in this last snow. I rolled toward the snow pile with the boom up and bucket dumping a load. The tractor slid into the snow pile with the bucket at full dump position. Not real hard or anything real unusual but.... at high rpm, the bucket did not want to curl back? It was moving to curl position very slowly and straining the pump. all other functions are normal. After a full curl back, at idle the bucket tilts forward and curls back smoothly. raise the rpm's and it strains to curl back again? I reversed the bucket lines and it seems to move smoothly. It's a but odd to see it operate in reverse and since the loader valve has the "speed dump" feature. (Regen?) Anyhow, today was nearly 40 degrees and I tee'd a 3000psi pressure gauge on the lower bucket cylinder hose. (the curl) and when straining to return I saw about 1600 psi. I then decided to swap the hoses on the valve right to left and let the boom spool power the bucket cylinders and the bucket spool power the boom. this worked fairly well but so backward. I actually loaded a bunch of snow this way and got the hang of it. The cylinders seemed to function normally leading me to believe the valve is at fault. when I returned home, I swapped the hoses back to normal and the trouble returned. At any rate, I understand that an aftermarket valve is in order and I need to decide regen or no regen (speed dump). I dont mind this swap but I really would like to know what went wrong all of a sudden? Hoses are new, fluid level correct and was changed about 100 hours ago. any idea what failed in the valve block? linkages are tight and spools move and detent as they should. strange one for sure. I would appreciate any insight. thanks so much.

If the dump spool is regenerative you cannot reverse the bucket hoses. It simply wont work. Put them bsck in the proper locations.

Then do sime testing before condemning the valve. I doubt its the problem.

Dan