I think you should grasp the nettle and first give your engine
a very thorough major service
, oil is cheaper than metal and get in the habit of checking it every time you use it for fluid levels, fan belt tension etc. Dismantle and weld the exhaust leak properly,(the gunk they sell in auto shops definitely works, but indefinitely) reassemble and you will by then understand your installation
much better. The metal grinding sound you hear may well be the gearbox
in the primary stages of seizing and the engine is stopping because it's overloaded. In my experience packless seals
do not spray mist when installed and I would consider retensioning the seal/ bellows on the shaft log. I don't mean to sound abrupt but someday your life may well depend on that engine so prevention is better than reparation.