Look downward behind the fan and you'll see a large nut (about 1 7/16") attaching the fan clutch to the water pump pulley. You have to turn this bolt counter clockwise while keeping the water pump pulley from turning."how can i keep the pully form turning on the water pump so i can get the big nut loose?

you could cinch and old soft leather belt around it, but then you'd have to find a place to post the end of the belt...could bear down on, and jam something like a book of matches in the belt to stop it from turning...an impact pressure will work better than a steady pressure in this appication.

Like a duckfoot tool for a harmonic balancer/crankshaft pulley puller

like a pulley puller one might use to replace a GM harmonic balancer~ every grease monkey has one of these collecting dust~

...or slip and put a wrench into the harrison~