i agree with LarryMo! i also use a strp wrench but pull the spark plug out and poke some rope into the cylinder to block the piston from rotating and then use the strap wrench around the impellor to remove it. when you replace the impellor,use some antiseize compound on all of the threads.and you only need to tighten it just a little more than hand tight. its removal direction is the same way the pump turns,so it tightens itsef as the pump runs. and DONT EVER use any penitrating oil on any part of that pump or youll regret it when ever you want to use it for gold! but thats just my advise!