Originally Posted by
sliderman
Cray, the tuner does bolt up on that motor. The issue I'm seeing is that there are too many possibilities to accurately guide the owner in making a repair. Of the many things I've seen on those motors, the magnets are trouble free and if one were to come loose, it would wipe out the stator. Not rattle. The rattle could be in no certain order; loose flywheel nut, failing top crank bearing, rod bearing, piston slap, detonation, loose tuner or powerhead attachment bolt, or something coming loose in the lower unit and resonating up the driveshaft. And there's probably some more things that aren't coming to mind at the moment. Those motors suffer from an issue were small gravel or vegetation collect behind the thermostat which leads to an overheat problem. Based on what I know, his best option is to contact the rebuilder or a competent tech and have it checked out.