2008 304c cr Been having an issue for while now, haven’t had time to investigate. When I boom up, especially with a load in the bucket, the boom bounces when I stop. No slop in the pins, I can see the cylinder rod bouncing. I doubt it’s an issue with the cylinder, the machine has less than 600 hours and no leaks or damage to the cylinder. Any help would be appreciated, I search but did not find anything helpful. Also on an unrelated note, my auto idle won’t work. When I switch it on, it goes into low idle but won’t idle up when I use the machine. Just replaced the pressure sensor but no change.
bump. any help is appreciated!
The boom cylinder may not be holding enough pressure immediately after the boom raise function is stopped. The pressure in the boom cylinder may be bleeding down or is not being metered correctly on the return of the boom spool into the neutral position. Possible causes boom seals. boom raise line relief. load holding valve assembly on boom cylinder, if applicable. load holding valve assembly on main control valve. Boom spool. Auto idle issue could be electrical such as a relay , power supply or wiring fault. I do not have access to any CAT literature but if you post your serial number then someone maybe able to assist you with diagrams to help with troubleshooting your issues. best regards
Air trapped in the cylinder/lines? I've had some machines, new or used, that I've had a dickens of a time getting the air out of a cylinder.
The bounce could be trapped air in the cylinder. The auto idle is probably a pressure switch not sensing the hydraulics being used. There should be one switch for the main functions and one for travel.