Hello everyone, I have a 2014 Caterpillar 277D, s/n FMT00336. I’ve just gone through and set pressures with a new gauge given my old one was reading incorrectly. I happened to notice while trying to set the implemented pump standby and system pressures when I shut the machine off the pressure would drop to zero. I believe there is something wrong with the pump just trying to confirm. I don’t believe the pressure at the tap should drop to zero when the machine is shut off without the system being bled. It would instantly go to zero as the pump is shut off. I could see it slowly going to zero but not instantly.
If I’m not mistaken it does look like it has a path to bleed off circled in blue here. The issue I am having is with heavy attachments both the tilt and arms are bleeding off whether the machine is off or running. If the pump is keeping pressure on the system while running this shouldn’t be the case I’m just trying to diagnose is it is the implement control manifold or the pump at fault.
Since they share a common line out I bet I have one bad hydraulic cylinder on the tilt and the lift.
So I did confirm that does bleed off the implement pressure. But what started this whole witch hunt is when lowing the arms slowly I get a chatter that shakes the entire machine does anyone know what would cause that?
Looking at the hydraulic schematics I can see maybe this machine has proportional speed up but not down from what I’m seeing so maybe there is nothing wrong I just don’t know much about this machine compared to my others.