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FEL problem

R

Randy Stuart

New member
I have a AgKing 2840 tractor with a Koyker 140 FEL. I was having problems with the control valve so I installed a new one. Everything works fine except when I move joystick to raise bucket it will initially drop instead. If I continue to move the joystick in the raise direction it will raise and operate normally. This is no big deal when moving dirt but can cause problems with more sensitive lifting like equipment. It can cause damage and might become dangerous. Everything else works as it should. Does anyone have any idea what the problem might be? Thanks.
 
blown seal.
typically it's a shuttle valve, high pressure comes in the middle, exhaust out the up or down port.
sound like the down seal is blown - as soon as your move it off 'total block' it lets a squirt out the down port before the up port uncovers.

alternately: slop in the linkage
alternately: blown seal in the bucket cylinder(s) - allowing high pressure to do the dip before pressure builds on the up side.
 
Thanks for the reply. Where would the shuttle valve be? I just changed the piston and gland in one of the bucket cylinders due to leakage at gland. How could I diagnose the problem?
 
the first step is to determine if air is getting into the system. should have mentioned that before.
after the system is warmed up, check the tank for any kind of bubbles or foaming.
air in the system can cause all manner of weird issues.

if you put a load in the bucket and then turn off the machine, does is stay up? or slowly come down?
 
Randy Stuart said:
It only does this when raising bucket slow. If you pull it back quickly it doesn’t drop. Does that mean anything?
Click to expand...
chowderman said:
the first step is to determine if air is getting into the system. should have mentioned that before.
after the system is warmed up, check the tank for any kind of bubbles or foaming.
air in the system can cause all manner of weird issues.

if you put a load in the bucket and then turn off the machine, does is stay up? or slowly come down?
Click to expand...
I will check today and let you know. It has good lifting power . I turned down the pressure at the valve to try to slow it down and that helps some.
 
I raised it with a load and it does fall slowly but very noticeably. Does this point to a cylinder leak down?
I have replaced seals in on side at the same time I put in the new control valve but have not touched the other side.
 
Randy Stuart said:
I raised it with a load and it does fall slowly but very noticeably. Does this point to a cylinder leak down?
Click to expand...
The problem with hydraulics is that sometimes you have to hunt around to find the bad seal, but clearly it is leaking down. A new system can hold a load for hours with only a slight drop, some will hold a load over night and still look to be near the top the next morning. If you can watch it leaking down then you need to start looking for seals that have gone bad.
 
yup - something is leaking.
any oil spot anywhere under the machine? if it's leaking oil, that's an "external" type seal issue - anywhere from pump to piston...
different issue - gaskets, etc, are suspect.

no external leaks, an internal seal is letting pressurized oil leak by - back to the sump.
that's what the slow fall shows.
could be seals, could be check valves.
you can start trouble shooting by disconnecting one lift piston - load, hoist, OFF, sit.
since both sides are connected to same lift and same drain lines an internal seal (those are double acting pistons... they have not only the seal around the shaft exit, but also internal on the piston itself)
will result in (a) the disconnected / idle side piston expanding as the load falls
or
(b) 'idle' piston is not leaking. does not expand, but the 'still loaded' piston is leaking by.

don't do just one side. repeat and check both sides to ensure the problem is isolated.

do you have the owner's manual?
 
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