Old Tractor/Loader - Loader "Sloppy" - Hydr Contro

I have a 1966 Massey Ferguson with a Davis 102 loader on it. Run off crankshaft pump. Just got this setup put together last fall. For as old as it is, it seems well built and works very well with the exception of one thing. When I go to lift the bucket I have to pull the lever the whole way very quickly or the bucket will drop. Meaning if I try to ease into lifting the bucket it actually drops. Much more rapidly if it has weight in it. The same goes with lowering the bucket. IF I try to lower something very slowly or easily, sometimes (not always) the bucket drops as if I pushed the lever the whole way. For example I was moving something last night with a chain around the bucket and when I went to lower it slowly it immediately dropped about 2 feet in split second.

Local guy has new hydraulic valves that he said will work. $150. Is the issue I'm having the hydraulic control valve?

I had that same issue with a loader, it had a "Cross" brand valve. I called Cross and talked to a very nice lady. She told me the valve needed an internal check valve and sent me the parts to repair the valve. It was a simple repair took ten minutes. The parts were sent free! Hope you can get what you need to fix yours. joe

Yes. Excessive wear in the valve spool, or simply the design of the valve itself, will cause this.

Just get the new valves with the understanding that you can take them back if it does not fix the problem.

yes or hydraulic pressure, the pump being too small for the loader, my little john deere does that unless i have some good rpm going on the engine, and its all factory, its an 850, give it 15oo or so and its fine, but idle up to a pile to dump, and it drops the bucket when i move the dump stick, its a 2 stick setup

I think I will try a new valve. The new valve will also have float which mine doesn't now.

I don't think it is pressure. Even if I idle up it does it. Also, I would think I would be seeing other issues with lifting capabilities and what not, but maybe not?

my old JD#35 did that when I had the original valve on it. I put new valve on with internal check valve and fixed the problem. I suspect you could put an external check valve in but you best bet is just to replace the valve, they get worn over time

You need a valve with an internal check valve or if your valve has them they are not working. My newer JD5105 with loader was wanting to drop on a slow lift and sure enough it had a bad check valve.

I finally got around to looking at this closer. I need help understanding what I have and how it works. The loader frame holds the fluid. There is a suction line at the bottom of the loader frame reservoir that goes to the pump and then a hydraulic line going to the loader control valve. Then there are 4 ports that go out and tee off at various points, going to top and bottom of each of the 4 double acting cylinders. So here are my questions:

1. I have to assume that the excess fluid coming back into the control valve is plumbed into the reservoir directly behind where the control valve is mounted. I don't see any line coming back into the reservoir. Is my statement accurate?

2. The new control valves the local guy has have an out port, but if the out port is where the excess goes and that is behind the mounting bracket I seem to be screwed there. It seems like there would be a lot of fabrication and hose work to get this to happen.

3. I'm thinking about trying the external check valve since that would be much easier and cheaper to try first and see if it works. Where would I install this check valve and do I need more than one?