Hi ive got an older case 688 I think it's around 1987, it was retired from excavation and has been used around our farm for a while now. Recently it all of a sudden started having a problem...When you start the machine and start moving the controls the engine stalls and won't start back up. The only way you can start it is if you relive the hydraulic pressure by cracking a relief valve. It seems like there's way to much pressure in the system and something is not letting the fluid back to the resivor. Not too sure any suggestions would be helpful thanks
hi Aaron may be the problem is the main relif valveyou must graduate the pressure start in nou pressure and increse this step by step if you dont found any result you must change the relif valve.
Update...The machine only shuts down when you curl the boom in and out. Usag61 should I still be looking at the main relief?
Aaron, if you know your S/N and if it has a Linde or a Rexroth main pump it may help some. does your arm cylinder have a valve block on the rod side port of the dipper cylinder ?
Aaron if the problen is in one hidraulic cylinder check that cylinder first maybe have an internal problem with the pistom or any other damage in the rod(to twist) .the other problem maybe is in the rod of the valve it have a graduation of the stroke is this stroke is incorrect the valve dont open and the fluid dont croos it this produce the shut down