We recently acquired a Kobelco SK210LC sn#YQ07-U0404 that hasn't had any maintenance done in a very, very long time. The travel speed seems slow and weak on the low side and when I switch to high side the left track doesn't move at all. I have rebuilt the swivel and the travel pedals because they had external leaks but no change in function. Also when I activate the operator present switch the pumps change tone and the travel pedals jump slightly, not sure if this is normal. I have removed the pilot return line from the top of the swing gear to get an idea of the return volume from the travel motors and it seems like it's returning quite a bit of oil from both motors. Any help would be greatly appreciated. Thank you.
High pilot return flow from both travel motors is a strong indicator of worn travel motor seals pilot oil is bypassing internally instead of controlling the motor displacement properly. symptoms point to: Travel motors: Internal wear causing: Weak performance (oil slipping past pistons) High case drain/pilot return flow (what you're seeing) Complete failure in high range (left side) where motors need full displacement Two-speed valve issue: Left motor not working in high range could also be a stuck/failed shift valve prevents that motor from going to high-speed mode Operator presence switch behavior: The pump tone change and pedal jump is normal it shifts pump displacement or activates a spool when you sit down (safety/performance feature on Kobelco). Test to confirm: Measure case drain flow from each motor individually (disconnect lines, route to bucket, run 1 min) - excessive flow = motor rebuild needed Check if left motor shifts mechanically to high range (linkage/solenoid issue vs. internal motor problem) After that much neglect, I'd bet on motor wear . Both likely need rebuilds or replacement.