I've got a Samsung Se50-3. I had the pump out of the machine and bench tested/inspected, because I wasn't getting any functions from the pilot system(the joystick functions and blade control did not work, but the boom swing and tracks, which are run by linkages, did) . The pump checked out 100%, so I re-installed it and added new hydraulic fluid. When I started it up after all the normal bleeding procedures (opening bleeder on pump, cranking the machine a few times), the machine still exhibited the same symptoms. However, a day later, the machine's functions start to work, albeit still not at normal speed. They then slowed down though until I got nothing. I tried it again after letting the machine sit and the same thing happens. Is it air in the system that's bleeding out and then getting reintroduced somehow? I looked for loose connections and sweating hoses and didn't see anything conclusive. It's the correct fluid, I have the owners manual and service manual. I don't think the fluid is overheating because the tank and pump seem to be staying cool. I've been staring at the hydraulic schematics during sleepless nights, and haven't been able to nail a cause down. My current thought is to let the machine sit for a few days and see if that will get all the air out, if there is air. I cleaned the breather and it was in good shape.
hi first of whats the hours on the machine did you check the low pressure pump, if yes you mite have a worn valve chest,oil seals between the slices worn/hard.
The machine has 2282 hours. All the pumps are housed together, there's actually four pumps in one. All of those got checked out and were 100%. So you're saying a possible O-ring failure, causing fluid to pass over the spools for the functions not operating? Would that cause all the functions to uniformly slow? I guess it would if it was a part of the system close to the pump. There's a solenoid that allows flow to the joysticks that is operated by the safety switch, which if it was sticking could conceivably cut pressure to the joysticks and then the main control valve. I know there is voltage to that solenoid, I just checked it today. Do hydraulic solenoids slowly cut off pressure sometimes?
that cuts oil flow to servos, did you do a flow test. if thers is a faulty oring or valve slice giving trouble when machine is cold it will work until the oil will heat up then it slow down or stop
I think you're right about the temperature making it worse. It's a nice warm 70F degrees today and I could barely get anything out of it until it stopped. Before it was always about 20-30F degrees cooler. I'm tearing into it to look for bad o-rings.
did you put a flow metre on the pumps
I didn't put a flow meter on there, I don't have one. But what I did do was completely disconnect the solenoid that allows fluid to the joysticks when the safety lever is on and nothing changed, still got slow function at high rpm. I checked voltage to the connector for the solenoid, which was good. Hence, this leads me to the conclusion that the solenoid is not functioning, hence no controls at low rpm. And when the rpm are turned up, the oil flows over the valve and into the system, instead of through the drain line. Tomorrow I'm going to see if I can take the solenoid apart and find out what's wrong, maybe get it to unstick, without losing all my new hydraulic fluid.