I have a 336 with a hyd issue When you stick out or boom up or even operate the thump the bucket will curls. Pretty much all functions except if you were going to dig. I’ve removed the load check valves checked relief pressures every checks out. I’m thinking it’s in the spool valve maybe the spring is broke and not returning to center not a 100 sure. Has anyone ran into this before?
Serial number
A very good possibility there.
compensation valve
I've had issues with the make valve spring unspiraling and wedging the makeup valve seat open. The make up valve is in bottom of the relief valve. When that occurred, the cylinder would drift. In other words, put the bucket in full carry or full dump (depending on which relief), and it would drift to neutral. The new relief valve (same part number) has been revised to prevent spring unspiraling. So, is your bucket powering itself, or is it just drifting to neutral (following gravity)?
I pull the compensater out and swapped the bucket to boom. That was my first guess. No change
No it not powering it self. The bucket will drift a little bit then stop. But stick out or boom up the bucket will curl not stick in or boom down
Rza
Could it be an ACS fault/ ACS calibration issue?
Wowsers...is that thing state of the art different. Perhaps a joystick error?
Haha ya it’s pretty hytech!!!! I actually came across that calibration test and the ivm calibration test. I’m gonna plug into it tomorrow with et and see what I come up with. As far as a joystick issue it’s not. I unplugged all the solenoids at the control valve and the bucket will still curl when you stick out or boom up
I think you're in the right area looking at the load check because two spools need to move to curl the bucket, the Bucket pump-to-cylinder head end spool, and the Bucket cylinder-to-tank rod end spool. They both seem to be drained along a common passage below the load check- maybe that passage is pressurizing and shifting the spools. There's some sort of cartridge looking shuttle valve or something in that cap over the load check spring. I'd have a look at that too even though I haven't seen what it's all about yet.
yeah - it sure looks like a rexroth sort of cartridge shuttle valve - I'd be pulling that out and checking/replacing the orings on it and seeing if the shuttle ball inside is good. Looks like it resolves signals from one side or the other to the load check- it might be passing oil through from one function to another.
So I removed all 4 bucket and boom spools and inspected they all looked good no broken springs. Today I swapped the lines reliefs on the bucket circuit just because. I also swapped the all the shuttle valves. I recalibrated everything again. Still no change looks like I’m pulling the whole valve body out and goin through it. Stick out boom up and even travel I’m getting pressure on the rod end of the bucket. This tells me there’s a problem with the valve body itself.