This has happened a few times on some bolts with a allen wrench end. Drill them out, all the pressure is releaved, and they come right out. So yeah, depending on where it snapped, and assuming it went it clean, and didn't bottom out, chances are it will come right out.

 

I had to do something like this on a busted stud left over from the DAPO (Dumb A$$ Previous Owner) of my M3. Intake stud broke clean flush with head. Dremel flat center punch, left hand drill nothing. so I got a bit 1/2 the size of the stud and drilled it all the way through. and then increased the size till it was nearly gone but shy of the threads. then it came out with tap. Ended up with a stepped stud and has been working like a champ.

 

LOL. That would be the "Is my torque wrench too small?" thread.
I can see this degenerating into a boobies thread. Calling KC.

 

Yeah it definitely went in clean and it was the correct length bolt. Looking at the head that snapped off and checking its depth in the old water pump, it looks like there should be enough of the threaded part to come out.

 

For this you should be able to take a dremel and carefully make a slot for a screwdriver if there isn't enough to grab it with anything.

Just carefully since you only really have one shot at it, and after that things may get a bit more serious.

 

At least on my motorcycle the exhaust studs can and do snap if you look at them wrong.

Funny though, the other 3 came right out for me, and the one snapped.

Ended up pissing around with easy outs for a hour or two at a friends place. Snapped one, ground it out, drilled at it more, and nothing. Finally (and what I wanted to do in the first place, which is what you did) took it on his mill and carefully removed the old stud and ran a tap through.

Not that the OP will have to go this far, or hopefully not, but if things start going downhill you're screwed and it ends up being a lot of work and swearing.