Loader leaking down and dumping

hrcarver · Dec 19, 2011

I have a m6040 kubota with a la1153 loader (w/ 3rd function and self leveling if it matters).

Both during operation and when off, the loader leaks down, the bucket dumps, and the 4n1 opens up (4n1 only during operation).

What's my likely trouble?

J_J · Dec 19, 2011

I would think if the bucket opens by it self, that your valve is leaking.

Is the valve levers returning to center?

If the loader lift were the only thing to leak down, I would say bad cyl seals.

Maybe a combination of both.

Have you checked things out with a hyd pressure gage test set. They only cost about $25.

hrcarver · Dec 19, 2011

Na, but I probably have enough stuff it would be useful to have one around. Could you tell me what I am looking for?

Far as I can tell, the levers are centered. Are they adjustable?

J_J · Dec 19, 2011

Most of the valves are spring centered, but if rust, debris, etc get in the detent, the spool might leak some. One of the springs might be broken or weak.

If you want to check it , look at a schematic of your valve and take the bottom cap off and inspect for equal spring tension.

With the engine running, and the valve in neutral, no fluid is supposed to flow to the cyl.

Pay attention to what you are doing, or you will squirt fluid everywhere.

To check cyl seals.

Remove the cyl pins from the rod end.

Remove one of the cyl hose and block off the removed hose, if double cyl are used.

Check each cyl.

Engine should be running. Fully extend the cyl, and remove the cyl rod end hose.

Activate the cyl again to extend. If the seals are leaking, a steady stream of fluid will come out that port.

If the relief valve does not activate when you max out the cyl, the seals might be bad.

Cyl's do a lot more work than a valve, however if the cyl check out, trouble shoot the valve.

If you remove the work port hoses from the FEL valve, and the engine is running, no fluid is supposed to flow or leak.

If all things are good, then the tractor should operate at the specs for your tractor.

jinman · Dec 19, 2011

Curl your bucket up and then remove the curl quick connects. If the bucket rolls down and the connectors don't leak, then your problem is in one/both cylinders. If the bucket holds, then the problem is in the joystick valve.

RickB · Dec 19, 2011

Jim's suggestion of isolating the cylinders from the valving requires no special tools at all and is a good starting point.
Cylinder piston seals can be checked with an inexpensive non-contact infrared thermometer without activating your valve when hoses are disconnected. An IR thermometer is more useful than a gauge in pinpointing internal hydraulic leakage as a leak will ALWAYS generate heat at the point of the leak. A gauge will tell you that a particular circuit can or cannot build pressure but offers little in the way of why or where without installing the gauge in multiple locations.