1988 Cat 426
Boom was very slow to come up... so slow in fact that it wouldn't build enough momentum to lock in transit mode.
Over the last couple days I've replaced every O ring on every resolver, both primary and secondary. While doing so, there were only remnants of what were once O rings on each one. I honestly don't know how anything functioned on the backhoe before. Now, everything works better, and much quicker, even at low RPM's.
The issue I'm having is that since replacing the O rings, the pump has too much idle pressure, even with all controls in HOLD mode. I can actually hear the pump whine now, and when starting the engine, it stops cranking after the 3rd or 4th rotation because the pump builds too much pressure. I can only start it if I actuate a hydraulic (any of them) to relieve the pressure build up.
My thoughts - since this backhoe is new to us, maybe the previous owners tried to increase that pressure on the hydraulic pump valve to compensate for the leaky/non existent O rings
- or -
While replacing the O rings, a chunk of one of the old rings is now floating around in the system and causing an issue
I really don't know what else it could be. Everything went smooth with changing them out with Cat OEM parts. All of the check valve balls are back in their place as well.
I though I'd ask opinions on here before adjusting hydraulic pressure or attempting any other fix.
Thank you in advance
Boom was very slow to come up... so slow in fact that it wouldn't build enough momentum to lock in transit mode.
Over the last couple days I've replaced every O ring on every resolver, both primary and secondary. While doing so, there were only remnants of what were once O rings on each one. I honestly don't know how anything functioned on the backhoe before. Now, everything works better, and much quicker, even at low RPM's.
The issue I'm having is that since replacing the O rings, the pump has too much idle pressure, even with all controls in HOLD mode. I can actually hear the pump whine now, and when starting the engine, it stops cranking after the 3rd or 4th rotation because the pump builds too much pressure. I can only start it if I actuate a hydraulic (any of them) to relieve the pressure build up.
My thoughts - since this backhoe is new to us, maybe the previous owners tried to increase that pressure on the hydraulic pump valve to compensate for the leaky/non existent O rings
- or -
While replacing the O rings, a chunk of one of the old rings is now floating around in the system and causing an issue
I really don't know what else it could be. Everything went smooth with changing them out with Cat OEM parts. All of the check valve balls are back in their place as well.
I though I'd ask opinions on here before adjusting hydraulic pressure or attempting any other fix.
Thank you in advance