water pump shaft
 

I found out that the kingpin wedge nut fits on the water pump shaft threads and works well to protect the threads when you are pressing the impeller onto the shaft.

Re: water pump shaft
 

That's a nice thought. Also for removing the fan by threading it not quite home and giving it a tap. An operation I have done by using a "coupler nut" (Long nut) and bashing the heck out of that. I have a few wedge nuts around here I think...

Joe K