Mercury 35hp 2 stroke Lower Unit Stripped

[Anglroc]

Hello all, first post here and looking for some needed help. My 1980’s (I believe) Merc 350 35hp 2 stroke needs an impeller change- should be easy, right? Well it was until I tried to take out the allen-hex bolt that holds on a little fin. First off, couldn’t fit a single thing in there. Couldn’t fit a socket, an Allen socket, nothing. So I drilled the hole open a bit more (I understand how jank this might seem, but you gotta do what you gotta do sometimes). To my grand suprise, BOTH the Allen AND hex head are stripped!! (See picture). At this point, I’m clueless on what to do. I tried to drill out the bolt but the metal shavings sit in the hole I’m drilling in and there’s no way to clear them out because of how enclosed the whole situation it. I tried to get a bolt extractor kit but I couldn’t fit the right size extractor socket in the hole and can’t drill it out any more. I’m considering a left hand drill bit but want to put it out there for any more ideas. Thanks in advance.

 

[Mc Tool]

Drill the head off the bolt. Stainless work hardens real quickly.....like as you drill. Get a couple of proper sharp drills ,some lube and a grunty drill and really lean on it. If you pussie about the bolt will work harden and you will likely ruin a drill trying to get thru it.
Once you have it apart you should heat the casting and tap the end of the bolt and wd40 it then get the vice grips in to play .
I do like your left hand drill idea , often the bolt will unscrew once you have hollowed it out a bit , but that is best left untill the bolt is flush with the surface and there is nothing left to grab hold of .

 

[Chris1956]

Gee, the trim tab is soft zinc, right. Drill some holes in it and using a chistle, crack it off the bolt, piece by piece. Now replace the bolt and the trim tab.

A lot of those old motors had a hex head bolt, that required a thin wall socket to remove. An allen head bolts works well also.