having a problem with my s160. I has low hours but the bucket settles/sinks. it drops pretty fast. it will go from top to ground in about 5-10 min. so far I have resealed the spool valves, inspected the load check valves(they look like new) and I have plugged the lift arm bypass valve. where should I look next? if you raise the bucket and shut off the machine you can hear a hiss that could be hyd oil leaking past something. the sound seems to be coming from the control valve area. what could it be? lift cylinders? looking for ideas to check out.
If you can hear a hiss, look for a leak or loose connection. Most common reason for bucket drop is cylinder seals but they don't usually hiss.
Sounds pretty bad. I'd disconnect the cylinders from the circuit, and dead head the hoses with a gauge, watch the pressure decay. It should be slow. If it's only a few seconds you have a valve that may not be centering or scored
update. tonight I got a stethoscope and listened trying to pinpoint the problem. don't think its a cylinder. there is a distinct hiss of hydraulic oil leaking past something sound in the control valve area while the bucket is settling down. the noise seems to be coming from the smaller pipe in the picture with the white paint mark on it. any bobcat mechanics know what it could be? its a 2011 s160
if you mean the steel tubeline thats running forward from the T fitting, i think that goes up to the emergency boom down valve. ( it's the one with the red knob next to the seat. valve could be pulled up slightly, stuck/rusted in place, or the orings on the cartridge could be bad.