So I recently purchased a Yanmar VIO 27-3 with a hydraulic thumb. The thumb is acting up now...seems to work sometimes and sometimes not...will chatter a bit but mostly just doesn’t work when the thumb rocker is pushed either way. Help?? Where to begin....I’m new to equipment. I just changed out every filter and fluids on it and it still acts up alot.
Im not familiar with your particular machine but most all thumbs I have seen before generally work the same way. You need to determine whether you have an electrical or hydraulic problem first so you aren't chasing your tail trying to figure it out. Since I don't know how familiar you are in knowledge of either system, Ill give you a quick check I would do in your case. If you will remove both hoses from your thumb cylinder and stick 2 5000 psi gauges in them (one in each hose end), then hit your rocker switch in both directions several times. You should have the same pressure reading in both directions and they should be consistent. Also hold the rocker in each position for 5-10 seconds and make sure there isn't a pressure drop or build up. If your pressure is steady and consistant, your problem is likely the cylinder itself. If not, it still could be a hydraulic problem elsewhere in the system, or electrical. At least this is a place to start.
Usually thumbs operated by solenoid, solenoids being magnetic attracts fine steel particles inside of them, I would start at checking elec. contact wires and relay, then solenoid it self.
Here’s the crazy thing...I was running it after work today pushing around some debris piles and I could get the thumb to work most of the time if the excavator was in forward motion with the levers all forward....not every time but a heck of alot more than just sitting and trying to pick up piles....???
You mean your both travel levers forward or arm digger arm stretched out?
See if you hoses to thumbs cylinder is not kinked when arm is not in stretched out position, they might be too short!