Kioti CK30HST loses hydraulic power

[jmk121]

Hello, This is my first post. I see a lot of folks on this site who are very good at diagnosing problems so here goes.
I have a 2007 Kioti CK30HST tractor. The meter shows 1300 hours but I am not sure how accurate it is. I bought it 5 years ago with 650 hours on it and it has been great until recently. I am not sure about hour meter as I have read it has 10ths but no decimal. I have changed both filters and hydraulic fluid I used Kubota HST oil. The front end loader is a woods LC-96. Last fall I was bush hogging and got stuck in a ditch left side in the ditch right side out at about 35 degree angle. I tried to use the loader to drag myself out but it just did not have the power lift and curl me out of the ditch (it has done it before) . I had the bush hog at full lift. Since then I have used it some and the loader and rear lift has gotten weaker with each use. Now when the tractor warms up the lift will barely move and the three point wont lift at all. when cold it seems to be fine. I have removed the relief valve on the joystick controller cleaned and replaced o rings with no change. I removed the mls valve and cleaned and replaced all orings. both seem fine visually. I checked pressure on the lift function and it is about 1700 lbs cold but is down to about 400 when it warms up. the pump leaks about a drop every minute but it is hard to tell where it is coming from. The dealer says the pump rarely goes on these. The dealer is about three hours away so I would like to fix it myself.
Any ideas!
Thanks in advance

 

[jmk121]

Also the HST drive works fine all the time and the power steering is ok as well.

 

[seville009]

If everything was working fine before you changed the hydraulic filters and oil, then I would start there. While it may be a pain, the possible simple solution may be to replace the filters and oil with ones specified for that tractor. That is what I would do at least.

 

[Roadworthy]

Your dealer is correct - those pumps rarely fail. Since you've changed fluid and filters it is possible one was defective or has failed. Find out if there is any screen in the hydraulic system which could be clogged. There is also a possibility it could be your over pressure relief valve. If your three point lever is in the full up position and it is not adjusted correctly that can also reduce loader power as it may be dead heading against the pressure relief.

 

[jmk121]

Thanks for the replys. I have changed the fluid and filters since the problem started with no change. I went from a daedong to wix on the hydraulic, and the hst is a daedong. I have looked in the manual and dont see a screen but will look again. The only pressure relief valve I can find is the one I removed and changed o rings on. it looks fine unless the spring has gotten weaker which I cant tell. I did try adjusting that relief valve when the pressure was low with no change. I have tried it with the three point lever in all positions but when it gets hot with a load on it, it wont lift at all in any position .

 

[Amvcane]

I can't recall what else besides the hydro filter is vulnerable under the tractor. If you think the problem is related to getting stuck in the ditch, maybe something cracked and is letting air into the system. Cracked hydro filter housing? Is the fluid foamy once its warmed up?

 

[jmk121]

No noticible foam on the dipstick when hot. I dont see anything obviously cracked, but have thougt that a loss of suction could be the problem. I have inspected all the lines under the tractor for kinks or bends and they look fine. The fluid is filled to the top line on the dipstick. I dont know if getting stuck caused it but that is the first time I remember a loss of power. Any ideas on how to check for a suction leak. all the suction pipe is dry except what is under the pump leak. there is a hose connection on the suction side of the pump.

 

[LS Tractor Owner]

My guess.... and only a guess.... is that something is not right in the pressure relief valve that you messed with.

could be one of the orings is holding something or it wasn't replaced correctly. Might want to check there.....

 

[LS Tractor Owner]

Another possibility is trapped air in the suction line. All points to when this happened is after you did the maintenance....

 

[jmk121]

Thanks, I am trying to decide if I should just buy a new presure relief valve or pump. I saw an old post on here where someone had similar issues and the dealer replaced the relief valve to fix it.