TripitakaBC
Member
I have a 2006 Cat 305CR, prefix DGT. 5300 hours.
First noticed a problem with the boom not pushing deep on a pit excavation but it then spread to slow lift on boom raise before finally quitting raising the boom altogether. I did some basic troubleshooting, looking for leaks etc and pressure-checked the pump which seemed OK. I checked the boom cylinder to ensure that it wasn't leaking internally and it checked out OK. I also switched control patterns to ensure that it wasn't an issue with the joystick controller. Same issue in either control pattern.
At the amount of hours on the machine I checked the hydraulic filter and pulled out the pleated material and found some metal debris in the pleats. Even though the pump pressure checked fine, I chose to replace the pump anyway.
I now have a new pump, fresh filter and oil. Same problem. I've pulled the line relief valves for the boom (second block backwards in the valve bank) and they all seem OK and have no debris in them.
Here is the kicker: if I dead-head the bucket curl, which operates on the same side of the pump (pressure tap P1) and operate the boom raise at the same time, the boom does raise. The same result if I boom swing to the left to dead-head it and raise the boom, the boom comes up. Without another circuit being deadheaded, the boom doesn't raise.
I'm getting out of my depth at this point so I'm looking for someone that can possibly explain what is going on and suggest potential fixes for it.
First noticed a problem with the boom not pushing deep on a pit excavation but it then spread to slow lift on boom raise before finally quitting raising the boom altogether. I did some basic troubleshooting, looking for leaks etc and pressure-checked the pump which seemed OK. I checked the boom cylinder to ensure that it wasn't leaking internally and it checked out OK. I also switched control patterns to ensure that it wasn't an issue with the joystick controller. Same issue in either control pattern.
At the amount of hours on the machine I checked the hydraulic filter and pulled out the pleated material and found some metal debris in the pleats. Even though the pump pressure checked fine, I chose to replace the pump anyway.
I now have a new pump, fresh filter and oil. Same problem. I've pulled the line relief valves for the boom (second block backwards in the valve bank) and they all seem OK and have no debris in them.
Here is the kicker: if I dead-head the bucket curl, which operates on the same side of the pump (pressure tap P1) and operate the boom raise at the same time, the boom does raise. The same result if I boom swing to the left to dead-head it and raise the boom, the boom comes up. Without another circuit being deadheaded, the boom doesn't raise.
I'm getting out of my depth at this point so I'm looking for someone that can possibly explain what is going on and suggest potential fixes for it.