Last week I did about 8 hrs of heavy FEL work with my 4100 HST and all was fine. I had it off for a few days and reinstalled it to again do some moving of gravel. It was then that I would hear a popping or light clunking sound from the front of the tractor when I had a full bucket and was moving. It sounded like it was coming from the front right but its hard to hear with the machine running. It went away after a while. I checked for loose bolts etc at the site and later at home even went so far as to take out the driveshaft to the front 4wd, thought maybe a bad u-joint. All was well. I double checked all bolts etc on the FEL and frame, even the front wheels. Found everything OK. The next time I used the FEL, it again made the noise a few times. All I can think of that I got some air in the system somehow and that's what is making the noise when I put a load on the FEL. Any ideas? /forums/images/graemlins/confused.gif