1990 evinrude 50 lower unit removed, broken bolt drilled... what's up there?

Howdy... drilled out the farthest-back lower unit bolt after it snapped off (too dang easily, I might add)... jiggied up the threads too much to be comfortable putting it back together without a threaded insert, that looks like it'll be workable... but, since I've never had the lower unit off before, I didn't know how far up into the bottom-mount area to drill through the busted off bolt (how much of the bolt was broken off inside the unit?), so I looked at the other four mount holes and they were pretty deep, so I figured the last one was supposed to go pretty far in, also... not so sure, now, though! I've drilled what appears to be all of the offending bolt material out, and where the end of the bolt will go is open to some sort of cavity inside the leg (?)... am wondering if this bolt hole once had a "bottom" and I drilled through it, or if it is indeed supposed to be open all the way through to the "cavity"... looking at the bits and pieces of drilled-out bolt, I'd guess that there was about a half-inch of busted off bolt stuck in there, and if it was indeed only a half-inch of bolt busted off, there very well may have been a bottom to the mount hole, and the exposed cavity that I see may not have been exposed before.

I'd take a pic, but don't think you'd be able to see enough up inside there for the pic to be helpful.

So, if any of that makes sense, I need to know if I drilled to far and dicked it up by going through the bolt-hole "bottom", or is that no matter? And how much of that bolt was up in there? I wouldn't be as concerned about it as I am, except that the other four mount bolts are 3/8, and this is a bigger 7/16 one, so it seems it may actually be important!

Also, goal is to replace all seals that keep the water out without tearing the whole gearcase apart... kit is on the way, would like to know which seals/orings of that kit are necessary to keep the water out.

thanks.... z

Re: 1990 evinrude 50 lower unit removed, broken bolt drilled... what's up there?

Have you got the new bolt, compare the lenth to the broken one.
When you drilled out the bolt did you drill far enough to get any aluminum(?) particles or just stainless steel?

Re: 1990 evinrude 50 lower unit removed, broken bolt drilled... what's up there?

Daviet said:

Have you got the new bolt, compare the lenth to the broken one.
When you drilled out the bolt did you drill far enough to get any aluminum(?) particles or just stainless steel?

Click to expand...

Nope, just drilled it today so haven't seen the replacement part, and was waiting on buying that to see if for some reason I have to change the size, like maybe not enough room to drill for an insert, etc.

Good thought on the stainless or aluminum... I guess thinking about it now it seems it was kinda shavingsy initially, and if I remember correctly, maybe particles after that. Shoulda been paying attention to that little detail, but metalwork's not my normal thing so just kinda went at it....

Since the other four mount holes have "bottoms", I was pretty sure I'd passed through an aluminum bottom on the broken-bolt one, so probably just need to know if it's a problem because of airflow or water flow or whatever.... I do believe once I put the insert in and then the bolt it'll be just like new as to "flow" concerns. I will make sure the insert and bolt do not intrude into the (probably newly accessed) cavity.