Loader drifts down when starting up

[BCinVA]

Have a John Deere 4400 tractor with 430 FEL. Boom got to where it would only move very slowly up, and not at all unless I had the RPM's up pretty high. Everything else on the loader seemed to be fine. I had a small leak in the hose feeding the boom. I replaced that thinking it might help, but it didn't. I figured it had to be the spool valve. I took the spool valve off the tractor. That was a big job. Pulled the spools out and inspected. It was clean as a pin and the spools seemed to be in pretty good shape. Washed everything in clean solvent. Re-assembled and reinstalled. Went ahead and changed hydraulic oil and filter and cleaned pick up screen. The loader now goes up pretty good. The only issue is that when I pull back on the loader control the bucket initially starts to drop down before it starts up. So if I barely pull back on the joy stick it goes down, but if I continue pulling back, it goes up with good power as it should. If I take it up and let the control lever go back to the neutral position it holds fine, with no drift down. I can't remember if it did this before. Has anyone got any idea if this is normal on this loader, or do I still have a problem? Thanks in advance for any comments.

 

[bigdeano]

Many loader valves have load check valves to prevent the drop you're getting. Do you remember if yours does? If it doesn't then it will do that.

 

[BCinVA]

Many loader valves have load check valves to prevent the drop you're getting. Do you remember if yours does? If it doesn't then it will do that.

Thanks for the reply. I am not really sure. There was a very small check valve right over the top of each spool. It consisted of a very small plastic piece with a small spring over the top of it. There was a plug that held those in. I took them all out and inspected. they all looked good and the springs were good. I cleaned them with everything else and reinstalled. They would only go in one way as they had a very slight taper to them. The other two spools, (one for the bucket curl, and one power beyond to raise a mm mower deck), don't seem to have this issue. The only other thing I saw on there was a pressure relief valve that was adjustable. To be honest I just can't remember if it did this before. Maybe I am just noticing now because I was looking so closely for problems when I tried it after repair.