Next gen Cat 320 wont destroke

[Maxwedgehead]

I have a 2018 next gen 320 cat excavator serial HEX01610 and I'm having an issue with pump 1 staying upstroked. This happened originally in December and we put a new control valve on that pump and the issue has been gone ever since.

Originally it happened instantly in the morning at first start up. Today we were using the machine fine all morning, came back from lunch and it wouldn't even idle at normal rpm. Turned the dial up and the engine revs extremely slow and you can hear the pump is loaded just like last time. Checked the service screen and verified at idle pump 1 is around 2000psi with pump 2 at 250. At wide open throttle its 4600psi on pump 1 and 350 on pump 2. I'm having a hard time believing a control valve is bad again with in 6 months. We are going to try to swap control valves tomorrow anyways to see if it changes to the other pump. Any other ideas why it would be doing this? Could the pump itself have something internal wrong with it that would cause this? Machine has 5900 hours with nearly half of them being idle hours and wouldn't think it would have a wore out pump already.

Also checked joystick outputs in the service screen and the machine is not sending any voltages to any functions indicating its trying to stroke it on its own. Pump unplugged it stays the same pressures.

 

[Deimos]

After replacing the control valve, did you calibrate the pump?

 

[Maxwedgehead]

yes we calibrated the pump after, we also rebuilt the other control valve as well, adjusted them while calibrating and it passed back in december and we have used it without issue since then.

 

[Deimos]

Additionally, calibrate the joysticks. The display doesn't always reveal the problem with the joystick.

After swapping the control valves, recalibrate the pump, then calibrate the pump and main valve. If there is a problem, the calibration will fail and a calibration error will appear. This error will help you determine which component is faulty.

 

[Maxwedgehead]

Swapped control valves, did all the calibrations, played with the adjustment screw since the valve we rebuilt is now th one on pump 1. Machine passed all calibrations, machine functions just like it should except pump 1 at wide open throttles standy by pressure is 1000psi and pump 2 is 500psi. At idle both pumps are at the same standby of 500psi. Currently running the machine as is, still don’t believe it’s completely right.

 

[Deimos]

If all possible calibrations have been successfully completed, there shouldn't be any problems. Any malfunction of the pump or proportional valves will prevent calibration.

If the problem persists, replace the pump assembly.

 

[Maxwedgehead]

According to TC standby pressures should be equal. Found in cat sis possibly stuck spool valve? Says to swap delivery hoses and see if issue goes to other pump

 

[Deimos]

At minimum engine speed, are the pressures on both pumps consistent?

At pump standby ready or hydraulics unlocked with solenoids plugged in will be around 3447.4 kPa (500 psi).

With solenoids unplugged or at pump standby with hydraulics locked will be around 1379.0 kPa (200 psi).

 

[Deimos]

Were you able to swap the supply lines from the pump to the main control valve? What was the result?