When an internal repair is needed on a Briggs & Stratton engine, you will have to remove everything from the PTO shaft in order to take off the oil pan to get inside the engine. The PTO shaft protruding from the base of the Briggs & Stratton engine usually has the drive pulley bolted to it. The drive pulley is the main pulley the makes a belt rotate at variable speeds and runs another machine's pulley.
Flip the Briggs & Stratton engine on its side so the PTO shaft is facing toward you.
Tighten the pipe wrench onto PTO shaft above where the drive pulley is bolted on.
Fit the correct-size wrench on the bolt holding the drive pulley onto the base of the PTO shaft.
Hold the pipe wrench with one hand as you rotate the bolt holding the drive pulley onto the PTO shaft with your other hand counterclockwise.
Remove the bolt and pull the drive pulley off the PTO shaft.