Had a noise in my 4010. Kinda a sharp rap/knock...went away when lifting the loader...worse at higher RPMs....worse when hot.
Traced it to the Hyd pump....thinking a delivery valve...pulled the pump down and everything looked good, resealed. Noticed the coupler "tightening bolts" (on the split, for the splines) were loose when removing the pump. Reinstalled the pump, tightened them.
The only thing I had changed was to tighten the coupling bolts so the splines in the coupler clamped on the pump shaft.
Removed, resealed the pump for nothing...Oh well.