Sorry but
 

Because the fix is useful for a stripped 8MM stud-the one you've described
is a 10MM already.

ah i see
well, for now i think i'll just put a new o-ring with some rtv sealant and hope for the best. since i bottomed out the stud i can tighten it pretty tight and it does hold. i just know not to try to put 25 lbs to it like last time (as per the bentley manual).
my concern was that it may hold one of the main bearing in place or something along those lines. but if all it does it seal the case i think i should be ok.

drola - that cap nut goes onto a case through bolt, only in this case, and for the one above it, it is not a through bolt, but a stud. But it has the same job - to hold the case halves together around a bearing. In this case it is the large #1 crank bearing - the one with thrust surfaces.

I'd torque it to the spec for these M10 fasteners, which is 35 Nm, or 26 pounds/feet.

There is a way of dealing with the head studs in these engines: If it holds torque, stop worrying about it. When one no longer holds torque during a periodic check (say when setting valve clearance), time to take the engine apart.

I'd apply the same logic to this case 10mm stud.

Here is a picture of a case apart, showing the left side case half. I've not heard of these pulling the way head studs do on these mag cases, but John or Bruce may well have encountered this since they go through so many engines.

http://forums.pelicanparts.com/uploa...1481861765.jpg