I would sure look closely at the engine for case damage, I have cracked a case before like that above the engine mounts, click noise I would pull the engine apart, or at least the rear cover off and see if it is the conrod crank hole worn out or the pistion end has damage, the dieing on impact, most of the time is the element being knocked out of the glow plug, so before you spin that engine again get the glow plug out and make sure if it did loose the element that it went out the exhaust completely and didnt tear up the piston and sleeve.
Well that answered your post backwards, LOL. Post back if you have questions.