Brand new CB65 backoe problem- UPDATE

[Fiziksgeek]

Someone correct me if I am wrong, but if you extended the boom then disconnected the hydraulic lines and it still bled down, wouldn't that tell you for for sure if its an internal leak on the cylinder?

 

[ray66v]

Yes.

But, I am not sure if you could disconnect the lines, with pressure in them.

 

[Billrog]

Since it held with the new seal for a short time I would guess there's a good chance they could have damage an O ring or the back up ring or piston seal when replacing which can be a bear to install properly.

 

[brettskermetzger]

Hey plowhog,

Just recently purchased a gc1720 and am noticing a similar issue with my backhoe...did you ever get this figured out?

 

[frugalangler]

Someone correct me if I am wrong, but if you extended the boom then disconnected the hydraulic lines and it still bled down, wouldn't that tell you for for sure if its an internal leak on the cylinder?

I'm not a hydraulics expert, but on the CB65 if you detach the lines from the tractor, the valve is still in the circuit as it's part of the hoe, and the QC is between the hoe and valve, and the tractor.
I'm curious also, because mine also sags if I leave it extended, but then again I was under the impression ALL hydraulics sag, hence never trust a hydraulic (anything) and always put a mechanical safety device (jack-stand, prop rod, etc.) in place to prevent injury due to sag. Mine only has 38 hours and every cylinder will sag under weight, 3PH, BH dipper and bucket and stabilizers, FEL lift and curl, all will over time. When I detach my BH, I put a stack of lumber under the frame because the stabilizers will sag, and the main arm will rise and I'll return to a BH frame flat on the ground. It jumps right back up when I attach hydraulics, but I just don't want it sitting on the wet ground if not necessary.

 

[jeepcj7]

A couple points. First, you can never have a zero leak valve, the valve spool always has to be a little smaller than the valve bore or the valve spool will never move when you try to move the valve lever/handle. 2nd - you need to determine where the leak comes from, the cylinder or the valve. It is very common for a cylinder to leak internally. To check for an internal cylinder leak, you need to either fully extend or retract the cylinder, remove the hose from the rod end of the cylinder if the cylinder is extended or from the barrel end of the cylinder if the cylinder is retracted. Wipe off any oil where the hose was removed, start the tractor and apply hydraulic pressure to side of the cylinder that is still connected to the hose. If a trickle of oil comes out of the cylinder where the hose was removed then the issue is the cylinder is leaking internally. DO NOT apply hydraulic pressure to the side of the cylinder where the hose was disconnected or you will spray oil all over the place.

 

[plowhog]

My cylinder apparently had a minor flaw. When a new seal was installed it would work for a short time, but a burr or something on the cylinder itself would re-corrupt the seal. A replacement cylinder fixed it.

If I park the tractor with the backhoe off the ground, it will slowly bleed down overnight until the bucket is on the ground. That is normal. But seeing it visibly dropping while the tractor was running was not normal. Again, a new cylinder fixed everything ...

 

[irvingj]

Thank you for the update!