Kubota3321
New member
- Joined
- Sep 22, 2023
- Messages
- 4
- Tractor
- 2000 b2400
I just purchased a tractor that doesn't move.
The former owner said he owned and operated the kubota for 3 years with no issues. Once the tractor hit 300 hours he decided drain the hst fluid and change the hst filter. He said he used kubota udt fluid and a kubota hst filter. He drained the fluid from the pickup screen drain plug. After the service he "drove it around the house" and it worked fine. The next day he went to move it and it would not drive anymore. I asked why he changed the fluid and he said it was due at 300 hours based on the maintaince schedule in the manual so there was no issue(s) that prompted it.
I'm planning to change the hst filter for the heck of it (curent one is new from Kubota) and drain the fluid completely next if the filter changes does not help.
It sounds like the nosies I'm hearing and the chattering are caused by cavitation from not getting enough fluid to the charge pump. I checked the lines feeding the hst charge pump and they seem to have good flow but the pressure gauge still reads almost 0 and it should be 40-70psi.
WSm Pg 154 attached has the flow diagram I have been using. It looks like the charge pump pressurises the cooler and then flows to the hst filter then feeds the high pressure pump. This means a flow restriction could be present any where in that circuit. I pulled the drain plug off the hst filter and fired up the tractor and oil immediatly started to flow much faster out of the port indicating to me that the lines are clear up to the hst filter atleast from the charge pump. Port P3 is where my low pressure gauge (150 psi range) is connected to check the charge pump pressure.
For the heck of it, I checked the loader valve pressure and got 1500+ psi so it appears this engine hydraulic pump is working.
I was exploring the possibility of the charge pump relief valve being stuck open but I inspected it and it appeared intact and the spring was in good shape. I'm going to pull the high pressure check/ relief valves as well Incase they have issues as well.
Other than what I explained above, I was just wondering if anyone has other ideas of what to check before I split the tractor to look inside the hst charge pump. The timing of the issue starting right after the last owner's fluid + filter change make me feel like something simple is wrong and the pump is hopefully fine since there are only 300 hours on it and fluid was fine and clean when drained.
The former owner said he owned and operated the kubota for 3 years with no issues. Once the tractor hit 300 hours he decided drain the hst fluid and change the hst filter. He said he used kubota udt fluid and a kubota hst filter. He drained the fluid from the pickup screen drain plug. After the service he "drove it around the house" and it worked fine. The next day he went to move it and it would not drive anymore. I asked why he changed the fluid and he said it was due at 300 hours based on the maintaince schedule in the manual so there was no issue(s) that prompted it.
I'm planning to change the hst filter for the heck of it (curent one is new from Kubota) and drain the fluid completely next if the filter changes does not help.
It sounds like the nosies I'm hearing and the chattering are caused by cavitation from not getting enough fluid to the charge pump. I checked the lines feeding the hst charge pump and they seem to have good flow but the pressure gauge still reads almost 0 and it should be 40-70psi.
WSm Pg 154 attached has the flow diagram I have been using. It looks like the charge pump pressurises the cooler and then flows to the hst filter then feeds the high pressure pump. This means a flow restriction could be present any where in that circuit. I pulled the drain plug off the hst filter and fired up the tractor and oil immediatly started to flow much faster out of the port indicating to me that the lines are clear up to the hst filter atleast from the charge pump. Port P3 is where my low pressure gauge (150 psi range) is connected to check the charge pump pressure.
For the heck of it, I checked the loader valve pressure and got 1500+ psi so it appears this engine hydraulic pump is working.
I was exploring the possibility of the charge pump relief valve being stuck open but I inspected it and it appeared intact and the spring was in good shape. I'm going to pull the high pressure check/ relief valves as well Incase they have issues as well.
Other than what I explained above, I was just wondering if anyone has other ideas of what to check before I split the tractor to look inside the hst charge pump. The timing of the issue starting right after the last owner's fluid + filter change make me feel like something simple is wrong and the pump is hopefully fine since there are only 300 hours on it and fluid was fine and clean when drained.
