I have a question on a kobelco sk300lc, mark IV, s/n: YCU0756.
Here is my problem, every function on the excavator works fine and the boom goes down fine but has no down force pressure once it meets the ground it will lift the excavator about 1 inch off the ground fast but stops and pluses like it is releasing pressure somewhere, it reminds me of the mode that some other excavators have when you have a sheep's foot installed where the machine eliminate all the down force pressure, except I don't have that mode on this machine from what I understand, we had our kobelco dealer out and haven't had any luck, I have removed the boom spool and disassembled the valves and found a broken spring on the boom down side poppet valve, It is 1.50 lbs. per square inch so I replaced it and ended pulling all the spool on the valve body to inspect them and they were fine and free, I removed the boom holding valve and I found a valve that was sticky so I rolled it on a flat stone and its free (boom holding fine), I have 4,800 psi at both front and rear pumps, I removed all the pressure relief valves for the boom, stick and bucket and checked them and they seam fine, I removed the conflux valves and poppet valves and they are free and in good shape, the boom cylinder's were repacked maybe two years ago and seam fine and the oil and filter are new, I checked all 6 of the valves under the cab and checked the diodes too and there all good, the only thing left to do is take apart the joystick and inspect the poppet valve there ? does anyone with Kobelco experience have any ideas ? is there a mode for this machine for a sheep's foot ? thanks for your help.
Here is my problem, every function on the excavator works fine and the boom goes down fine but has no down force pressure once it meets the ground it will lift the excavator about 1 inch off the ground fast but stops and pluses like it is releasing pressure somewhere, it reminds me of the mode that some other excavators have when you have a sheep's foot installed where the machine eliminate all the down force pressure, except I don't have that mode on this machine from what I understand, we had our kobelco dealer out and haven't had any luck, I have removed the boom spool and disassembled the valves and found a broken spring on the boom down side poppet valve, It is 1.50 lbs. per square inch so I replaced it and ended pulling all the spool on the valve body to inspect them and they were fine and free, I removed the boom holding valve and I found a valve that was sticky so I rolled it on a flat stone and its free (boom holding fine), I have 4,800 psi at both front and rear pumps, I removed all the pressure relief valves for the boom, stick and bucket and checked them and they seam fine, I removed the conflux valves and poppet valves and they are free and in good shape, the boom cylinder's were repacked maybe two years ago and seam fine and the oil and filter are new, I checked all 6 of the valves under the cab and checked the diodes too and there all good, the only thing left to do is take apart the joystick and inspect the poppet valve there ? does anyone with Kobelco experience have any ideas ? is there a mode for this machine for a sheep's foot ? thanks for your help.
No down pressure on boom on a kobelco sk300lc
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