Does anyone know how to remove the heavy, castiron impeller from the crankshaft? I have the protective housing removed and can't figure out how the impeller slides off the shaft. Any ideas?

Take out the bolt in the center. Screw in a 7/16 fine thread bolt (the longest thread you can find) and keep turning. The male end will hit the tapered shaft and push the impeller off.

Hi,
Cannot easily say sight unseen. Universally you can bet on a bolt in the center securing it to the crank. It will also be keyed, usually 5/32" square stock. There may may also be set screw(s) holding it in place(again 5/32" Allen wrench to loosen if there.) Many manufacturers make some provision for pushing the impeller off, such as a threaded area underneath that bolt in the center. Got a model#?
Peace,
Clarke

Thanks for the post Tim. This worked just as you posted. There are no other keepers or square stock of any type on my machine.