I have a new to me Cat 420d (11341). Dipper cylinder leaks promptly down (pulling the shaft out) when fully extended where the shaft is fully retracted. I held the pilot controls open with the cylinder fully extended and completed retracted for around 1-2 minutes each direction after a cold startup. Cylinder did get warm at each end of the cylinder where hose ports are located. Does this indicate internal seal issues? Planning on a seal kit, but don’t want to waste money if there may be pilot or resolver issues. Thanks much!
It's not likely a leaky relief valve if it's working properly and if it's working properly most likely not a resolver So my bet would be gland seals I bet the seal kitsch a hundred buck ish so the only thing wasted is time if it's not the gland seal
The company I work for has a 420e that does the same thing I'll get to it some day.
Sorry, serial is BLN11341
Seal Kit has been obtained. Now just have to find the time to get the cylinder disassembled.
Update. Internal seals were damaged. All is back to normal after a overhaul.