Hi Folks, need some help trouble shooting my old Cat 320L / 320A. Staggers when put to a hill, walks on the flat fine. staggers under load while lifting logs etc. Worse when hot. Seems to slew ok but when hot its possible to lift a load or force it up a hill to the point engine stalls. Recently replaced a hose that went from a block behind the hydraulic tank to behind the boom, where there was a coarse mesh filter that had some black rubber particles present. Not sure if this is relevant to the situation. Only had machine a few months. Went to change final drive oil and found it was mostly grease in there. Also probably not relevant to the situation. Thanks for any assistance offered.
Is it possible you're not getting enough fuel when hot? Is it black smoking when trying to stall?
Could be an engine low power problem but could also be a pump output control problem. The 320 has a pump regulating solenoid valve to destroke the pumps when the engine rpm drops. This is controlled by a computer which gets an rpm signal from an engine speed sensor. The solenoid valve sends a pilot pressure signal to the pumps to destroke them . You would need to hook a gauge into the signal test port to see if it's working. The signal pressure goes up to destroke the pumps. I think somebody here could post a picture of the test ports. I don't have access to it right now. There is also a hidden button on the dash of a 320l that will let you check the electronic side of things. On the bottom right there is a soft spot on the keypad. Press and hold that button while turning the key on. Hold it until the dash changes to display 320. You can go into prv display mode and see what signal the ECM is sending to the prv valve. I'm can't remember which mode it is but I will look it up when I get a chance.