The digger bucket will not stay closed when used as a hoist or grapple. We have to keep pulling the lever to retract it. It must be some leaky rings in the hydrolic manifold block. How difficult is it to DIY some valve work on this. I attached a CNH diagram of the block. What are the gotchas of working on the block?
Creeping hydraulics can sometimes be difficult to repair - have you checked cylinder for creeping without the valve in the system? This problem is often resolved by resealing the hyd. cylinder as most of the wear & tear happens there. Test cylinder like this - Position the hoe on the ground & disconnect the hoses going to cyl & plug them off - don't loop the hoses - then raise the boom & see if you have any movement - if bucket creeps with no valve attatched, the problem exists in cylinder.
The check valve in the inlet section is a "load check". It's function is to hold the load up when the valve is shifted, it opens when the pressure in the inlet section equals the pressure to hold the load up + the spring behind the check valve. It will not cause creeping, only load to drop slightly when the valve is shifted. More likely problem is in valve bank (leaking spool, crack, or overload relief valve)or the cylinder. Swap the hoses on the valve bank or at an easier location, such as at the cylinder or hose to tube connections on the boom. if the creep continues it is probably the cylinder, if the creep stops it is probably in the valve section. If it seems to be in the valve section, swap the port overload reliefs on the the valve section, no sense buying a valve if it is just a relief cartridge.
My mistake, the check valve in the enlet section is probably a regeneration/anti void valve, the load checks are in each valve section. however it is connected to all the circuits except swing so if it was to leak you would see either creep in all the circuits or none, not sure that it would have any effect. Also, is this original valve? I still believe that it is either in valve section or cylinder.
It is the original valves. All the cylinders were repacked last year before I bought it. However, it could be a bad repack on the digger bucket cylinder assembly.
Try placing the bucket flat on the ground and then open the bucket to lift the machine off the ground. If the cylinder is leaking the machine should creep down, these cylinders will leak both ways if the packing is bad. You should also have packing material in the filter. If the cylinder only creeps in one direction, it points more to the bucket section of the valve, a crack or port relief. If you swap the port reliefs on the bucket section and the cylinder creeps the other way, the relief is most likely the problem. Some times if you back out the adjustment on the relief cartridge all the way (if it is adjustable) then activate the circuit, I have had the relief blow out a piece of trash and then go to work.