Backhoe hydraulic leak

CC644 · Jul 5, 2023

Hey all,
I have a Cub Cadet 8454 with a 644 backhoe attachment made by Kioti. Like many on this site I had a leaking valve body that controls the boom stick. I learned that there are no parts available for the Cub Cadet 644 or Kioti kb2365/75 hydraulic valves, same Nimco CV556 controls. Nimco no longer sells any parts for these models. I am in search of a used valve body as mine has a crack in the casting and cannot be fixed. Please let me know if anyone knows where I can find a used Valve body also called “work section body”. Cub cadet part #KD-bc01-0200. Kioti part #BC01-0200.

dfkrug · Jul 5, 2023

Isn't that just the dust cover for the end of the spool and its spring? You should be able to have a replacement machined to fit.

CC644 · Jul 5, 2023

The cap I can get. And probably can fix but look at the top of the picture on right. See where the seal goes, the casting inside broke right where the seal sits.

oldnslo · Jul 5, 2023

Any idea what broke that casting?

CC644 · Jul 5, 2023

I don’t know. I am not completely sure If the spool cover cracked first or the tiny piece in the top section let go first. Either way, I saw the crack in the spool and brought the unit to a hydraulic shop who disassembled it and showed me the missing piece of casting in the top.

wdchyd · Jul 5, 2023

Looks like too much return line pressure, maybe something added downstream without using PB port for a second valve or 3ph?

CC644 · Jul 5, 2023

I don’t quite understand what that means. Can you explain please.

dfkrug · Jul 5, 2023

What WDCHYD is referring to is the possibility of over-pressuring your OUT port on the valve stack. Backhoe attachment hyd valves are not usually fitted with a Power Beyond port, just an OUT port. If that port exceeds about 500psi, you can get breakage inside your hoe valve.

How does the OUT port get over-pressurized? By connecting it to the IN port of another valve, like the 3-pt cylinder valve. Usually that does not cause a problem in this case, but if the 3-pt cylinder is operated to relief, then bad **** can happen.