03 cat 308 c cr. 6000 hours. If you raise boom all the way up and turn loose of controls it will fall to the ground in probably 20 seconds, but you can pick the machine up with the boom and it will stay there all day long. Re did packing/ seals in cylinder, still same problem. Assumed it was line relief so I swapped line reliefs with the bucket and swing, still same problem. I took the spools out and springs seemed to be in good shape and didn’t see any other problems. I am stumped. Any ideas?
Try looking at the diagram posted below. These boom lock valves are common in the control valves and installed in the main valve bank. Item 8 " poppet" may have a damaged seat. This is all I could find online but if you post a serial number of your machine someone who has access to the CAT SIS information maybe able to assist you further with better diagrams. Best regards
Do you know the location for said boom lock valve? Serial # kcx 01070
There is a valve mounted on the bottom end of each boom cylinder.