Bobcat 463 Hydralic noise

[wiiggan]

Hello! This is my first post on this forum. I have a Bobcat 463 2001 skid loader and i have started to get some buzzing noise from the hydralic system. The sound occurs at +50% rpm when i move the lift cylinders quickly and stop moving the lift cylinders quickly. I still have full power and i can get rid of the sound just by lower the rpm. The machine has been running for 100 hours since new hydraulic filter and hydraulic oil. What sould i look for? Thanks Wiggan