[Keith True]

Screw a head nut onto a head stud a turn or so,then weld it there.Then screw that onto the water pump shaft,until it bottoms out.Make sure the nut doesn't bottom out on the fan.If it does put some kind of shim on the end of the pump shaft.Tighten it real tight,then hold the fan with the pump hanging, hit the stud with a hammer.A real hammer,and don't poot around with it.No tap,tap,tap crap,belt it.Watch your toes.I know you haven't put too much pressure on it with a puller,because you haven't broken the pulley.The amount of pressure they can take without breaking is tiny.