My 580M boom cylinder leaks down in operation if I don’t latch it. It doesn’t leak externally. In my experience with industrial hydraulics, cylinders were much more likely to leak externally than internally. If a cylinder started losing its position, the problem was most likely in the control valve. Does this logic carry over to mobile equipment hydraulics? Any wisdom on whether the problem is more likely to be in the control valve or the cylinder? It's only a nuisance now but it's gotten worse over the last couple years.
Internal seals rot just like the external. How fast is the drifting?
The piston can leak internally allowing the boom to drift down. My 580SM was doing the a few yrs. ago . After many theory's from experts about where the problem could be I decided to check the valve body. To my surprize the cup on the bottom ( for lack of proper term) was loose , I tightened it by hand and the drift down ceased. That was about 10 yrs. ago simplest fix I've ever done. And owning backhoes for the last 35 yrs. trouble shooting and repairing cylinders and valve bodys I would have never in a million yrs. thought that could cause the problem.
Takes about 20-25 minutes.
Billrog, are you talking about the hydraulic valve body that controls the boom up and down?
Does your machine have ride control? If so that valve can cause the symptoms you are seeing.
Yes , the boom control valve.
No ride control. Checked the boom control valve today and found nothing loose. I won't dig into it this winter. Maybe check it out next year.