Sorry to resurrect an old thread but I now have EXACTLY the same problem with my Yamaha 30 6J8's (yes both of them
) - does anyone know if this was ever resolved?!
I soaked the bolts in plenty of penetrating oil before attempting removal but they both stuck. The first one I thought was actually coming out but I was clearly just twisting the shaft, the second went almost instantly. The remains of the bolts are corroded to the casing and are holding the lower unit on very securely.
As far as I can see my options are to leave this alone until I get an impeller problem, which seems pretty irresponsible. Or to try to find a solution. Reading through this thread and online I'm wondering if centre punching the stud and trying a very fine reverse drill bit might be a good way to start but it sounds unlikely that I will be able to accurately drill these by hand.
Any further suggestions gratefully received.