A classic mistake is to install the pump pulley backwards. That one action will cause the belt to be misaligned and can also cause it to drag on the pump body. Even if you haven't had that pulley off, chances are somebody from the past did............so check that 1st.

The noise could also be caused by a failing bearing inside the idler pulley (the one mentioned in my previous post). With the belt off rotate that pulley by hand and make sure it spins freely. It should glide without any resistance and should feel smooth. Any resistance or roughness means the bearing inside is shot.

Another cause for the noise could be a clogged screen/filter inside the reservoir. CLICK HERE to find out more on that. Tim