Kawasaki K3V112DT pump issue.

Machine: Samsung SE210-2 with 5800hrs. Symptoms: Right track motor is slow and weak. Bucket is a little slow. Arm in when Multi-functioning hits vertical, stops then jerks into action again, fine when just pulling arm function. Machine will track straight when swinging. Testing: Re-sealed swivel joint All pressures meet specs when stalling functions including both tracks. Pulled and inspected both main reliefs and swapped them. Pulled and inspected Foot relief valves and swapped them. Pulled and inspected boom and arm logic valves. Verified correct pilot pressure at pilot pump. Track tension correct. Swapped travel pedal pilot lines at spool caps. Observations: When regulator on P1 (which controls lazy track) is cranked in I can nearly make machine travel straight however machine becomes jerky and super responsive. I cranked the regulator in a half turn. When main delivery ports of P1 & P2 are swapped at the pump the issue transfers to the left track and swing and bucket become very slow and machine struggles to lift itself when booming down. These functions are like this even when only pulling one at a time. What Im struggling to understand is why a single function like swing or bucket curl is so dam slow yet when the main delivery ports are swapped back to original position the single function is so much better. I'm leaning towards either P1 regulator or P1 excessive wear. Any advice greatly appreciated.

When you swapped P1&P2 did you also swapp the negative control pressure hoses fl and fr? Have you checked the negative contol pressure?

Kje Kjell said: When you swapped P1&P2 did you also swapp the negative control pressure hoses fl and fr? Have you checked the negative contol pressure? Click to expand... No neither. The fact that I didn't swap the 2 negacon hoses explains why the machine acted the way it did. Good pickup, thanks

Negative pressure results: P1 regulator: ~470psi before command dropping to as low as 70psi when commanding multiple functions. P2 regulator: ~485psi before command dropping to as low as 80psi when commanding multiple functions. I observed little to no drop on P2 when only functioning arm, similarly on P1 when only functioning boom.

When you measure single action arm and boom was it with the arm and boom moving or att cylinder dead end? Main and chock relief valves feeds the negative control pressure circuit at the relief operation.

Kjell said: When you measure single action arm and boom was it with the arm and boom moving or att cylinder dead end? Main and chock relief valves feeds the negative control pressure circuit at the relief operation. Click to expand... With arm and boom moving

Sorry. I am wrong about relief pressure feeding the negative control pressure circuit on the Samsung 210-2. It did on my Kobelco 400lc when i tested it many year ago. On the Kobelco 400 the negative control pressure was very responsiv to the work load no mather single or multiple operation. It is not the same hydraulic system but Kawasaki K3V pump and negative control system. I had both pumps connected with long hoses and the gauges in the cabin and operated the machine several hours because i wanted to learn how the system works. 470 psi negative control pressure means minimum pump torque.

I'm seeing pilot pressures at regulator drop in line with what I would expect based on what I'm commanding from the machine. This just brings me back to P1 pump or regulator producing lack of flow.

You might be right about the regulator, but I dont understand the Negative pressure results in post number 4. If there is no drop in the negativ control pressure in single operations the pump will not start to flow. It will stay at Qmin. Also start pressure is 384 psi in the diagram in post number 1 . 470 psi seems to be pilot pressure.

Kjell said: You might be right about the regulator, but I dont understand the Negative pressure results in post number 4. If there is no drop in the negativ control pressure in single operations the pump will not start to flow. It will stay at Qmin. Also start pressure is 384 psi in the diagram in post number 1 . 470 psi seems to be pilot pressure. Click to expand... While single functioning boom or arm the Qmin may be sufficient to supply enough oil without needing to stroke the primary pump as both pumps are combined through conflux valves. Still, I would've expected to see some pressure drop. If this is the case it could indicate a healthy P1 internals and point to a faulty regulator. The machine has sat for long periods and I did change the oil 7 years ago as it was milky. This issue was present then.

Lack of pressure drop indicates an MCV issue. Maybe it can be the regulator leaking through and feeding the negative control system but i dont know. Negative control pressure is main pump flow return pressure, not pilot pressure.

I don't believe it's the MCV as the issue transfers to the left track when I swap the pump feed lines over.