Hello Professional!! My PC160 swing would drift and had no power. I replaced the valve plate and it is almost fixed. However, only the left swing drifts. I have swapped the swing safety valve left and right but no change. Please advise.
Have you touched your left side joystick at all, replaced, repaired, fell on etc. ?
The left joystick is not touched. About 5 seconds after starting to drift, the engine speed drops and the brakes lock and stop. But the joystick seems to be leaking a little oil.
or it maybe possible that an anti-cavitation valve is not fully seating in the head cover.
This valve??
yes that's correct. They can fret on the seats and can wear in the housing and has high leakage out the hose that is positioned between them in your photo.
I tried to remove it today but it was held in place very tightly and I gave up. I would like to purchase a long breaker bar. Do I need to grind the seats together after disassembly?
Grinding the seat faces back in the housing will require a full strip down and clean out. Try testing the unit on the machine first but the only issue is with the hose connectors as they are Komatsu metric cones so not the most common to be able to plug and connect a drain hose too. Test by removing and plugging the hose that goes to the boost check valves and seeing if it bypasses oil out of the port when applying only a very small amount of stall pressure ( 50-100 bar /725-1450 psi) when stalling the swing motor out in each direction by extending the boom and arm all the way out and the bucket sitting hard down onto the ground. Keep the engine rpm at idle and try to run the port connection on top of the swing motor back into a large empty drum or the main hydraulic tank with a hose so if in the event you apply too much pressure and hit the relief setting you don't end up spraying oil every where.