First time posting! I've searched all over the net and in this forum but I can't find an answer to my issue. I have a 2013 IHI 35vx-3 excavator that I just purchased. I'm a excavator newb so go easy on me. When I purchased the excavator the previous owner had removed the thumb so I installed a new one. Now that its installed, I am having an issue where the thumb will slowly bleed down. At first it had no clamping force at all. If I tried to pick anything up the thumb wouldn't hold pressure on it. I reversed the hoses on the cylinder and that fixed the clamping issue but now if I have the thumb fully up, it will slowly leak down and I have to use the thumb control to raise it back up. If I get off the excavator and push on the thumb it will slowly close just by me pushing on the thumb with my hands. I can't lift it but I can close it. The cylinder is brand new (purchased at USA attachments with thumb) so I don't think the cylinder would be the issue. I know there is a valve that I can turn on the excavator and in the owners manual it states that the valve should be one way for "iron fork" and then I can turn it 90 degrees to use a "breaker". It is currently set to the iron fork setting because I figured the breaker setting was for a rock hammer. One thing I think it could be is I had to purchase new hydraulic couplers for the thumb. The excavator already had couplers on the boom so I purchased new ones for the cylinder side to match the ones on the boom. I purchased "skid steer" couplers because they looked the same and they plugged in. I'm not sure if these are right or not because I know just because they fit doesn't mean they are always right. These are two way couplers (I think) and I noticed they offered one way couplers as well but I figured the fluid needed to flow both ways in and out of the cylinder. So....should the valve be set to "iron fork" like I have it now, or to breaker? Also, are those "skid steer" couplers correct? Any help is much appreciated.
Couplers are same (correct). Open thumb whole way, disconnect couplers. Now can you close it slowly by pushing on it with your hands? Iron fork is correct valve setting.
To me sounds like air in system.
Good day See the thread Bobcat thumb creep I guess you have a similar issue Kind regards Uffex
How fast do they leak down?
Switching the hoses should not have mattered. Sounds more like not having the valve opened up for two way hyd. operation.
Okay, I messed with it today and here is what I have. If i disconnect the hoses from the boom the cylinder won't move I can't pull it or push it (seems right to me). When I have it all hooked up it will close the thumb as normal and it is holding strong. When i go to raise the thumb up (close the cylinder) it will not stay up. It will creep down slowly. Takes about 10 seconds or more to fall all the way down and sometimes it won't even fall all the way. If I raise the thumb back up with the controls and then hope off the excavator I can push the thumb down. If i use my foot the weight of my foot will close it slowly. I figure it has to be leaking fluid back through the system from the bottom cylinder port. I messed with the breaker/fork valve and if its in breaker it will close the thumb but won't open it with the controls (seems normal) then when I switch it back to the thumb setting it will slowly leak back down. One thing I have noticed is if I just raise the thumb all the way, it will start leaking immediately. If i pump the switch a few times and bring it up (push switch the stop then push it again then stop...so on) it will stay up without leaking back down but I can still push it closed if I get off and try to close it by hand. I appreciate all of your feedback and for taking the time to help.
Your one way/two way valve may be leaking back, or the seals in the thumb cylinder are bad.
Relief valve compromised or set too low on the "open" side.
How do I adjust/check this?
I contacted IHI this morning and they said it was likely the control valve leaking for the thumb control. He told me I could check this myself but didn’t give me a guide on what to do. I know what the valve looks like so can I just remove this valve and inspect it without fear or messing things up hydraulicly?