Koyker FEL issue

[rstuart]

I have a 28hp Ag King (Chinese) tractor with a Koyker 140 FEL. The controls gradually went crazy. It would raise the bucket without moving the lever and bucket would dump on its own. I had a bucket lift cylinder with a bad leak so I installed new piston and gland. That fixed the leak but control problems remained. I replaced the control valve with a new one and most problems were cleared except one.
When I move the joystick to raise the bucket it actually will lower the bucket initially if joystick is moved a small amount. If I continue to move the joystick further to the raise position it will raise with no problem. The problem seems to occur only when trying to raise the bucket slowly or a small amount. Anyone know what this could be caused by? Thanks.

 

[oldnslo]

Does your new valve have load checks built into it. Some valves do and some do not. Without load checks the loader will operate as you describe.

 

[rstuart]

Does your new valve have load checks built into it. Some valves do and some do not. Without load checks the loader will operate as you describe.

What are load checks? The valve is made by Pace I think.

 

[oldnslo]

Do you have a schematic for the valve? A load check is typically in the pressure port feeding that valve spool. They prevent oil from escaping the work port do to higher load induced pressure vs system pressure. On open center system the pump flow is unloaded at low pressure so you need to shift the spool a certain amount to restrict the flow of fluid going through the valve and direct it towards the load. When you are feathering the control this can easily allow flow from work port back into pressure galley if their are no load checks present.