9/16 SIZE socket counter clockwise to loosen, if its stuck on the shaft spray it with wd40 let sit for a few days keep spaying it, clean the rust off the crankshaft, don't try to slide off any if it over a rusty crank!! i use a fine sandpaper, i get the guys old belts off a crankshaft polisher, i work next door to an engine shop, & spray some more, go easy parts aren't cheap.. good luck..