engine submerged in water

[whiskers]

If you don't have penetrating oil try heating around the bolt and apply a little diesel fuel dextron mix.
Left hand drill bits work well for extracting broke off bolts. Drill a pilot hole as nearly centered as you can, then run a little larger left hand bit to the bottom. If it didn't turn out move up a couple of sizes and try again. You can do this till most of the bolt has been drilled away, at some point you'll be close to the threads and it should turn out. Don't break off a bit and don't ask how I know this.

[tstex]

Thanks BT/whiskers...Once I get the hole drilled, I am going to shoot it with PB-Blaster/etc, then plug it with some metal roofing sticky-tape [does anyone else use this stuff for just about everything?]

The one question I have is how deep to drill, as to not penetrate the engine body, yet go deep enought to remove all of the remaing flange shaft?    I guess I could always leave her a little shy, then measure the distance needed to secure the muffler, and cut/taper the ends of the two new flanges...sound good? 

Dang, we haven't talked one iota about c-saws, but sure have come-up with a lot of good solutions...you guys are good!   

Thx again,
tstex
 

[Clam77]

Every time I've had to drill out a bolt, there's always a small amount of space at the bottom of the hole the drill bit will punch into to let ya know you're there - especially on exhaust manifold holes...  don't think I've ever found one that's been bottom seated...

Those bolts are gonna be HARD though from the heat tempering..

[whiskers]

The original bolts will have been just shy of the bottom from the factory. If it's bottomed  there's another problem that I don't have the solution. The block will be easier to drill than the bolt and the chips may be different. A piece of tape on the bit for a depth guide after determining how deep to drill may help. It's actually easier to do than describe. If there's room you might consider using studs with brass nuts, easier to remove next time.

[Al_Smith]

If you slobber them up with never -seeze you'll be able to get them out the next time .

[albirk]

If it is broke off flush try welding a washer on the bolt(5/16 bolt 1/4 washer) and then weld a nut on the washer I  do this about 5or6 times a day about 9 out of 10 will screw out if not get a center drill bit to start your hole they will not walk on you like a regular bit will get the hole started and drill with the biggest bit you can watch the bolt if you can see it if you see it more stop put in a left hand bit and it will screw right out.       good luck

[Al_Smith]

You can drill them out .A little secret is "step drill " them .in other words use a small drill bit then increase the size a tad untill you get to just about the size of the miner thread diameter  .Often times if you're real lucky the threads will back out like a coiled spring .

There's a little trick which only comes from practice of drilling out studs without ruining the thread base .You can burn them out with a torch too but that's another subject all together .