50 backhoe lost power

[crgenther]

I have a 50 backhoe on my 440ic. while doing some digging I lost power and range of motion on all hyd. cylinders. the first thing I did was check the fluid level , and it was fine . Next I changed the filter, and while the old filter was quite dirty, there was no change in performance. when I switch the selector valve to the loader it works fine, so the problem is isolated to the hoe. I am wondering if there is a bypass valve that is not working. possibly a dirty strainer or something. It would have to be in the valve assembly, as there is nothing else but hoses and cylinders.
Does anyone have any experience with a 50 hoe attachment.

Thanks,
Curt

[Stan Disbrow]

Hi,

I am unsure if the 440 has a separate hyd oil filter for the hoe or not. The later JD series all do, though, in their return lines.....

Stan

[Lavoy]

Possibly a broken pressure relief spring?
lavoy

[original possum]

Does the engine load when you operate a backhoe valve? If it does then check the quick-couplers on the pressure and return lines. If that doesn't fix it then look at the nylon balls in the valves. They can wear and wander.

[crgenther]

no load on engine when using valves.
all valves are affected . would one ball out of place affect all the other valves.
at the end of the valve assembly is what looks like a valve body with no spindle or handle that the pressure line and the return line go to. I took it apart but there are no parts to replace if it is a relief valve, I might have to split it from the rest of the valves to see if there is more to it.

[original possum]

John Deere parts catalog PC0619 covers the 50 and 51 hoes. There are different diverter valves and splitters depending on the application. I see a relief valve in all the selector valves, and this would be my first suspect. If you disconnect the high pressure line quick-connects with the selector set to loader, Start the engine and select backhoe it should load the engine up to the pressure of the relief valve in the selector. If it loads then the problem is in the backhoe control valve (probably relief valve). If it doesn't then the problem is probably in the selector valve. Don't do this unless you have three lines to the selector, as that kind has no relief valve. If a ball wanders it usually shells out a pump by blocking relief.