Hi I have a hitachi mini ex-35. I just rebuild the Kubota motor. The hydraulics were all strong and fast prior to the engine work. I reinstalled the pump when installing the engine, refilled hydraulic oil and bleed the air out of the pump with the Allen screw and hydraulic lines on the pump. I can’t get pump pressure to run the cylinders at a normal rate. When at idle they run faster then with higher RPM’s, there is no whining. There was whining initially then I shut it down and bled the system. I’ve attempted multiple bleeds but I suspect an air issue as the speed decreases when RPM’s raise. Any suggestions? All functions are slow, blade, tracks and stick. It has a Nachi piston pump.
Check your suction hoses. Most likely you have disturbed a old brittle hose or fitting. drive coupling is another common failure point.
Thank you for the reply! I’ll check it out tomorrow
I read the op manual for the newer model last night, it said the bleed procedure was operate it for 15 minutes at idle, then slowly increase speed for another 15 minutes. Works great now. I’ve never heard of such procedure but 30 minutes later it works even in a cold Wisconsin 10 degree night. Always learning!