Starter problem

Sounds like the starter might be taking a while to disengage, so the engine is spinning its overrunning clutch. As a test, grab a junkyard starter from a Magnum engine (~1987-2002 V-6 or V-8, Dodge truck or motorhome, Jeep Grand Cherokee, maybe $10). It fits fine and if the sound goes away he might appreciate the 1/2 size and weight plus more torque.