Very HOT Hydraulic fluid

sourmash2 · Dec 27, 2002

Hello all, I am a proud owner of a YM2420D which has recently developed a hydraulic problem.
Here is the history; while changing an implement the tractor was started with one of the quick disconnects not entirely seated. It sheared the key on the pump. This was replaced, the system bled, and all seemed fine, but after about 2 hours of moderate work with the FEL, the tractor developed a chatter in the lines and the fluid is getting extremely hot.
I am in the process of draining the system and checking the filter and screen, but any help or suggestions would be greatly appreciated.
Thanks in advance, Scott
P.S. I did a quick search of previous posts, but did not see anything addressing why the fluid would get so hot.

JohnMiller3 · Dec 27, 2002

<font color=blue>...It sheared the key on the pump...</font color=blue>

How about a bad pump...? /w3tcompact/icons/sad.gif (or severe line restriction and running semi-dry)

Perhaps, the pump originally almost seized (running dry or low on fluid), but didn't, sheared the key... ran again for a couple hours when you changed things (fluid etc.) but maybe the damage is already done...?

DavesTractor · Dec 27, 2002

I agree with John, it is likely that the pump is damaged. You can take it apart and look, and you will probably find a lot of scoring. I broke a pump once doing something similar. The key and keyway act as a "fuse" that is adequate to keep the pump from exploding, but not always adequate to keep it from harm.

Some of the F-series pumps do not have keys, instead they have a necked down portion of the shaft that acts like a fuse.

Anonymous Poster · Dec 28, 2002

Do you have a lever that is stuck or pulled too far one way and causing the hydraulics to over work it self?
I had that happen on my JD 4400 loader (4 in 1)the lever that was mounted on my fender which opened and closed the 4 in 1 lever was pulled back too far and causing the hydraulics to overwork and heated up the whole sytem,it took me a while to realize what was wrong.

sourmash2 · Dec 28, 2002

As a matter of fact, that was part of the problem. After doing more reading in the shop manual, I saw a proceedure for heating the hydraulic oil to perform certain tests. This is accompished by closing the slow return valve and raising the control lever to the up position, both were happening to a degree on my tractor (return valve closed 3/4, control lever up 3/4)
Long story short, I put it back together, filled with new fluid, set controls properly, and all seems to be working fine.
Thanks for the help, Scott