Kx121 excavator hydraulic problems

[dfunkyd]

Problems on my Kubota kx121-3 mini excavator are: Blade drifts down constantly making it useless for grading. Also, when the left travel lever is moved forward, the blade raises to full height. I've recently purchased 2 new check valves to put into the blade section of the hydraulic control valve stack but have not installed them yet. I'm thinking that the rotator joint seals are worn out and are allowing hydraulic oil to bypass them and migrate to places it's not supposed to inside the rotator joint. I believe the hydraulic fluid that is supposed to be going to the left drive motor ends up going to the upside of the dozer blade. Does anyone have experience or advice for these problems. Should I pull the joint out and reseal it? Am I wrong in what I think it might be?
I'm a new owner to this 2004, 5000 hour machine and am not a mechanic or experienced operator but am not afraid to dig in and fix things.

Thanks

 

[Cataclysm]

Your on the right track. Easy stuff first.

Raise the dozer blade up, block it up safe and pull the lines off the cylinder, cap the cylinder off, then pull the blocks and see if the blade still drifts down.

Is there a case drain on the rotator joint? If so pull it and see if hydraulic fluid shoots out when you run the left travel motor.

The shop manual for these is pretty cheap at Kubota. With 5k hours on the machine you might as well get one.

 

[dfunkyd]

Cylinder was rebuilt and is fine. I don't know what a case drain is. Is it attached directly to the rotator joint?

 

[BertZegers]

Cylinder was rebuilt and is fine. I don't know what a case drain is. Is it attached directly to the rotator joint?

You could locate the hoses from the dozer cylinder and the drive motor on the rotary joint. If they are next to each other, a broken seal in the rotary joint seems likely.

I once looked at the rotary joint in my KX41 and it did not seem to difficult to remove it.

 

[Cataclysm]

Case drain is just a non pressurized return to the tank from hydraulic motors. It drains any leakage from the workings of the hydraulic motor. Other wise the motor would pressurize and eventually blow out a seal or worse.

I will try to remember to look it up tomorrow and see if there is a case drain and if those two circuits are next to each other. The shop manual is very detailed and it takes quite a bit of time to find specific stuff sometimes.

 

[dfunkyd]

Ok I have a WorkShopManual and will also start looking for a case drain line. Thanks for your assistance.

 

[dfunkyd]

Thanks for the advice. I won't be near my machine for about a week but will start crawling around/under it when I get there. Any more advice you may have is appreciated!

 

[Clifton park]

My pusher blade and my tracks will move with the hydraulic lever in the Stowed position I’m thinking the sensor