hi guys! been searching this forum for a while and decided to join the party! i have a kobelco 295 mark 8 # u0818 with a crank but no start problem. Pumps rise to 4000psi each while cranking.... psv's are at 350mA... Unload's are a 750mA The engine starts really easy when i unplug any sensor or solenoid on the pump or any hydraulic parts... I noticed that when i unplug the travel pressure sensors on the pilot, unloads go to 0mA Cleaned all the ground connections and no code present. Each time I unplug something to start the engine, the related code appears but that is it. Thanks for all the inputs!
Not that many guys have worked on Kobelco Excavators. Hopefully someone will chime in with some suggestions. My only suggestion would be to remove and cut open the hydraulic filters to see if something has come apart. Simon C
when the machine runs, it works very well. the only thing I noticed is stick OUT loads the pumps at 4000psi no matter the demand, fast or slow
Is there any error message displayed on the screen? Based on your description, it appears that one or more operations have triggered a low-pressure sensor error. Consequently, the controller interprets the situation as an active operation and commands the pump swash plate to maximum angle, causing the engine to become overloaded and fail to start.
no error on the displey except when i unplug something to start it. At first there was a timing error, the wheel on the crank pulley was broken so we replaced it. Afterward we thought it was a fuel problem so we replaced the fuel line that were aftermarket. But now it seems like a computer misread or cross signal from somewhere but hard to say where.... Looking into the monitor data there isn't really a sensor poping out. Unload solenoid are at 750mA with everything plugged in. When we unplug certain pressure sensor, 1 or the 2 unloads get to 0mA and it starts
Carefully inspect the two "unload valves"; even if they are functioning correctly from an electrical control standpoint, they could still be mechanically stuck. Pay attention to the two "bypass-cut" lines; they operate in opposition to the "unload valves". Therefore, when you disconnect the low-pressure sensor connector, the controller detects a fault in the machine's electrical system and switches to backup mode. At that point, the main hydraulic circuit is vented via the "bypass-cut" valve, reducing the load and allowing the engine to start.
Good explanation with a picture to help. Simon C
Incredible! thank you very much!! If I understand correctly, at 750mA pressure will be at the entrance of the unload valve and bypass-cut. I do have seen them T a line to the solenoid. But would the machine work well with these stuck or partially stuck? I have noticed that stick OUT load the pump at 4000psi whatever the demand....
What are your pilot pressure sensors reading with key on engine off and then at idle with no functions. same with your high pressure sensors on the pump
all within reasonable range and electric signal with it. Confirmed the pressures with a gauge as well. The one that took my attention is E-3 and E-4 ( opt relief 1 and 2) that is always at 3146psi whatever I do with it. comp. 265-310mA around the same for the meas. If I unplug the solenoid, meas. goes to 0mA but 2900psi not sure where the reading is
Those two parameters are the "settings" for the safety discharge pressure control solenoid valve (an "option") and can be adjusted as desired by a technician. As you can see, they represent the solenoid control current "converted" into a corresponding pressure value. They are not related to the symptom of the engine failing to start. Unless you observe that parameters B16 through B19 are already having an effect before any action is taken.