broken idler pulley/tensioner bolt - '90 Lebaron

If you overtightened the bolt you stand a good chance of getting it out. If there's a stub protruding try just gripping it with pliers; once the head snapped off it should have relieved most of the tension causing it to be hard to turn. If that doesn't work, take a small piece of hardened steel shaft, grind a point in the end of it, and try to "walk" the stub out with a hammer (get it to rotate counterclockwise until you have enough sticking out to grip)

If neither of those ideas work, THEN break out the drill bits. A good, sharp drill bit is your friend here, as is lots of oil and a friend to drizzle it on the bit to keep it cool.

good luck,

nate

Speaking of drill bits, buy some left-handed drill bits made especially for drilling into submerged, broken off bolts/studs. Sometimes as you are drilling they will simply turn right out. Good parts stores will have these.