Rawze.com: Rawze's ISX Technical Discussion and more

I have a 2009 386 Pete with a 485 ISX. The fan belt squeals sometime when the AC is on and the engine fan kicks on. A while back I replaced the fan belt, then the belt tensioner and finally the crank pulley. The belt still squeals from time to time but not as bad. I was killing time on QuickServe and noticed under Manuals, then Installation Instructions Number: 4907798 Fan Drive Idler Pulley Assembly. From the drawings I thought it looked like it would help with my problem. So I bought the kit, but the parts will not fit behind the fan pulley. Has anyone tried to install this kit?

if pulleys are polished and too shiny, belts will squeal... groves get impacted with road dirt too .. remove belts and wire-brush the crap out of the groves for the belt at all the pulleys... also rough them up if you can, maybe put some toilet bowl cleaner on them and let em rust a bit, then wire brush them off again to rough em up.

I'll 2nd the wire brush. A few weeks back my belts were squealing every time the fan came on. After brushing the pulleys off the squeal is gone.