directional valve Yanmar loader

[jerhutch]

I purchased a used 3 spool valve for my yanmar loader. I was told that it was a good valve but the loader boom will not stay up, i.e., the valve apparenlty leaks oil. Can these valves be rebuilt and if so where would I sent it?
Thanks
Jerry

[MJPetersen]

It may be leaking internally, but it also may be a motor valve which allows bypass so that a motor is not stopped forcefully--think overrun clutch (kinda).

Some valves can be rebuilt, but major leakage indicates major wear and therefore, major parts replacement, ie. HIGH COST. Valve rebuild kits usually are simply a few o-rings, a couple of gaskets, and a seal or two, low cost items.

How fast does the loader drop when the valve is released?

Mike

[RonMar]

Usually the parts that would cause this type leakage are the spool and the valve body/bore that the spool slides in. both are not rebuildable, and replacing just the spool may not fix the problem. A rebuild seal kit usually is just to keep the fluid in the valve. What make valve is it? Got any pics?

[jerhutch]

The valve is a gresen. Also, I've noted that the boom will come up about 3 feet then stop; however, I can lower the boom to push the front-end of the tractor up - then the boom will raise clear up?????
Jerry

[RonMar]

Did this loader work correctly with the valve you put the 3 spool in place of? I noticed on your picture some unusual valve handle positions for a loader control valve. Are there 3 handle positions(In, center, out)? Is there some sort of detent to indicate when the valve handle is in the center/neutral position? Do you have a model/option number off this valve? All valves are not created equal and this valve might be for some specific use other than controlling dual acting cylinders.

[jerhutch]

Thanks
The reason the the valve handels are in the incorrect positions is that the little chain linking at the bottom was lost on the far right valve. I took the one off next to it to find a match.
The valve that I replace did not work. I sheered the woodroff/moon key off of the pump 3 times. Something was stuck????
Jerry

[MikesTractor]

Originally Posted by jerhutch

The valve that I replace did not work. I sheered the woodroff/moon key off of the pump 3 times. Something was stuck????
Jerry

That sounds like a missing or stuck pressure relief valve......... Does the loader have it own pump or does it share the tractor/TPH pump? Was there a pressure relief in the original loader valve? We need more pics...

[RonMar]

So have you ever seen this loader operate correctly? What is your history with this piece of machinery?

The last symptom you gave where the loader only goes up 3 feet untill you load it in the opposite direction by lifting the front of the tractor off the ground, then the loader will go full height normally, sounds like the valve is working fine and you could have a cylinder seal problem. It sounds like you may have a lot of unknowns. My best troubleshooting has always come from eliminating the unknowns.

[Leejohn]

Hi.
I looked at your picture and I think that valve isn't a good one for a loader. It looks like there are no load checks and as for as I can tell it doesn't have a float. Are they spring center? It might have the wrong spool in the first valve. You could switch the lines and see if #2 valve would work right and #1 gives you the trouble on the dump.

Good luck with it. Lee