I have a 580SL that the roll on the loader bucket doesn't hold. I have repacked the cylinders. And disconnected the hoses and put caps on and the cylinders hold. So I'm thinking it has to be in the control block. The control block doesn't have any external leaks. Would it be one or both of the check valves.
I've had the same thing happen with the boom once. All the was necessary was to tighten the cap by hand that is on the bottom of the control block directly under the curl or you may have to take the cap off and inspect for a problem or pull the control rod out of the top and replace an 0 ring or 2. It's been a while since I've done one so unable to give you more accurate advice.
Does it creep both ways? if you point the bucket down a bit and lower the loader so the front wheels are off the ground and the bucket is only touching in the front, and a few inches off the ground in the back of the bucket, will it hold or drop? I'd think that would narrow it down to a control valve leak, or a circuit relief valve leak, assuming it has a relief valve in both the tilt forward and back circuits. I wouldn't expect a load check valve in the curl, usually only in the stabilizers, but I don't know.
Yes it creeps both ways. And it has circuit relief values
Mine does that after I repacked the cylinders with ****** seals, didn’t do that before just leaked a little at the wipers. Lol
It could be the check valves or the spool could be leaking. Not likely, but it could have a crack in the body of that particular section.
Easy way to test the load checks, put the bucket in the air level with the ground, feather the bucket control just a bit if the bucket drops before it curls back it's a bad load check. Now curl back then feather to dump the bucket if it curls in before dumping it's a bad check valve. Common for load checks to go bad, but both Circuit reliefs bad is unlikely. Just another thought if the bucket keeps trying to dump be sure the anti roll back is not stuck or seized in the bushings. Tell tale sign is a slack cable. This can cause the bucket to want to dump at any height.