I've also had good luck hammering metric size sockets onto the bolt head. What the others said will work to.

TEWKS,
I have had success with a combination of what you have alreday received as replies...I.E. I have drilled the center of the head of the bad bolt, drill size of about 70% of the size of the stem of the bolt, ( not the head of the bolt)
Clean up the chewed up outer edges( rounded portion ) with dremel tool and pound on a metric socket.
I used an impact driver for removal. I expect 1 of 2 possibilites as a result.
Either the bolt loosens, or the head, of the bolt, breaks off. If the head breaks off, use the dremel to remove whatever is left that obstructs the removal of the head. You can work the stud out of the block with vise grips, heat, & your favorite penetrating oil.. etc. Use plenty of rags to prevent debris from the dremel entering the engine. Heat the block and not the stud. Blow torch is fine ( moderate heating ) cool the stubborn bolt ( makes it shrink ).. usually
attaching vise grips cools it down pretty good...
Good Luck.

TEWKS,
After re-reading your original thread, I realize that you don't have much of the bolt head left. Dremel has a cut off wheel, they are delicate, but if room allows, you could cut what remains quite cleanly. These cut off wheels are about the size of a quarter in diameter, and very thin.
Sorry for all of my previous verb-age.
Doug

You have had some good tips to help with your problem, I have had luck using one or all methods mentioned, but I also would suggest taking a LARGE punch or similar tool and smacking straight down on the bolt head with a hammer.This will sometimes relieve surface tension and sometimes free rusted bolts.

\Thats what I usually end up doing. Once the head is off, pipe wrench on the bolt shank.

try vice grips always works for me

http://buy1.snapon.com/catalog/item....re&dir=catalog


These are the ones you want. I have used the crafsman version and they work ok once or twice but after that they get too mualled up to work. also the smaller pieces in this set work well to grip the shank of the bolt if the head has broken off.

welding should work.

had one do that last year on a 502 was the short outer bolts VERY CAREFULLY cut the head off with a torch pulled the head off and vice grips took the remaining stud out. we were installing a set of darts so we werent too worred about messing the head up but it didnt hurt it at all.

I had some also .Ck out my thread

http://www.offshoreonly.com/forums/s...highlight=head