In this situation heat is probably out of question...
so-
KROIL.
A little had to find, but works wonders.
If not that, PB Blaster (most parts stores)
WD 40 is WORTHLESS for this.

Soak with Kroil or PB, rap with hammer, soak, repeat a bunch of times, good
luck

"William G. Andersen" wrote in message
news:LwPvc.38389$oi5.16111@fed1read07...
I didn't know about corrosion and the effects of different metals when I
added a wake board tower to my runabout 5 years ago.
The other night, a 5/8" stainless steel bolt failed at the point where it
threads into a solid aluminum mount. The bolt is corroded to the mounting
plate it penetrates. There's insufficient space behind it to knock it
through and not enough thread exposed to put a nut on it to pull it
through.
I sprayed it with penetrating oil and banged on it to try to get the oil
to
saturate the corrosion, but don't think it's going to work.
looks like I have to try drilling it out and using an extractor -
something
I've never been able to do before.
The frustration grows because the mounts are all inside the gunwales with
barely enough space to get my fingers or wrench inside. I never thought
I'd
have to touch the nuts after I got them installed.
So, the moral of the story is that I always use antisieze now, but didn't
know about it 5 years ago.
Any ideas on breaking the corrosion on this and other mounting bolts that
are sure to be equally corroded?