Front Control Valve Leaking on Linkage side (Passenger side)

[Vselsor]

Hi everyone, new to this page and after searching through multiple forums, I still cannot repair my issue. I have a 2008 BX2350 and have been dealing with a hydraulic leak in the front control valve. I believe the part # for the valve is U95002 for reference. Whenever I tilt my bucket up and down, hydraulic fluid comes out of the of the dust seal side (right side) of the valve in the most rear stem. I have replaced the O-rings and backer washers for both stems with Kubota parts and it is still leaking. I just ordered another set of o-rings, backer washers, and this time dust seals. When I raise and lower the bucket, no fluid comes out, however when I tilt it, fluid comes out pretty good (steady flow). The stems seem to be in great shape, no burrs or marking on them. I've scoured the internet looking for someone with this exact same problem and cannot find it. I am going to replace the o rings and backer washers again, and probably remove the valve and replace the dust seals but I'm pretty sure the washers and o rings aren't the problem, however, I don't know what would be. Anyone got any advice?

 

[TheOldHokie]

Hi everyone, new to this page and after searching through multiple forums, I still cannot repair my issue. I have a 2008 BX2350 and have been dealing with a hydraulic leak in the front control valve. I believe the part # for the valve is U95002 for reference. Whenever I tilt my bucket up and down, hydraulic fluid comes out of the of the dust seal side (right side) of the valve in the most rear stem. I have replaced the O-rings and backer washers for both stems with Kubota parts and it is still leaking. I just ordered another set of o-rings, backer washers, and this time dust seals. When I raise and lower the bucket, no fluid comes out, however when I tilt it, fluid comes out pretty good (steady flow). The stems seem to be in great shape, no burrs or marking on them. I've scoured the internet looking for someone with this exact same problem and cannot find it. I am going to replace the o rings and backer washers again, and probably remove the valve and replace the dust seals but I'm pretty sure the washers and o rings aren't the problem, however, I don't know what would be. Anyone got any advice?

Those are seals where the spools pass through the tank cores. They are not supposed to see any significant pressure - few hundred PSI max

Your symptoms indicate excessive back pressure on the tank port. Until you find and fix that you are going to continue blowing out the new seals.

Dan

 

[Vselsor]

Those are seals where the spools pass through the tank cores. They are not supposed to see any significant pressure - few hundred PSI max

Your symptoms indicate excessive back pressure on the tank port. Until you find and fix that you are going to continue blowing out the new seals.

Dan

Dan, thank you for the reply. Based on the parts diagram, the only part I can see which is inside of the valve on the side of the linkage are "dust seals." I am not a master mechanic by no means but can usually get by on easy fixes, which is why I've only replaced the o rings and plastic backer washers on the left side. Are you saying, the dust seals are bad and excessive pressure is causing fluid to blow by the dust seals? When you say "spools" are those the stems I've mentioned, two long metal rods with groves throughout them? Thanks, just trying to make sure I understand what you are saying.

 

[TheOldHokie]

Dan, thank you for the reply. Based on the parts diagram, the only part I can see which is inside of the valve on the side of the linkage are "dust seals." I am not a master mechanic by no means but can usually get by on easy fixes, which is why I've only replaced the o rings and plastic backer washers on the left side. Are you saying, the dust seals are bad and excessive pressure is causing fluid to blow by the dust seals? When you say "spools" are those the stems I've mentioned, two long metal rods with groves throughout them? Thanks, just trying to make sure I understand what you are saying.

The "stems" are called spools and they control flow paths inside the valve. Since they pass through the valve body they have to be sealed to prevent oil from leaking out of the valve. The point where the spools enter and exit the valve pass through through the tank return cavity on both ends of the valve. Since the oil in that cavity is never under any significant pressure the seals are not designed to handle more than a couole hundred PSI.

When they start leaking like you describe its usually caused by over pressure on that tank cavity. You can replace seals to the cows come hime but if you dont find as nd fix thd causebof the over pressure they will keep failing.

One common cause of tank back pressure is the loader tank return hose gets disconnected. Thats external to the valve. Off the top of my head I am not familiar with the details of the external plumbing on your tractor but I think thats where you need to look before blowing out more new seals.

Dan

 

[North Idaho Wolfman]

The valve is this valve:

https://messicks.com/parts/kubota/YS038-00100

No amount of O-rings, dust seals and such is going to fix it.

One long shot is that if these two parts have become unscrewed it will cause the valve to leak.

 

[whitetiger]

The oil is probably leaking from the #40 o-ring. You have to remove the spool from the valve body to replace it.

 

[TheOldHokie]

The oil is probably leaking from the #40 o-ring. You have to remove the spool from the valve body to replace it.

I think he has replaced that oring multiple times.

Dan

 

[whitetiger]

The #30 labeled "dust seal" is actually the hydraulic oil seal in the spool end of the valve.
It sounds as if you have only replaced the o-ring and backup washer on the detent end of the valve.