alternator bolt broke off in engine block

[hardycm]

I was doing some work in my engine compartment when I found that one of the bolts holding the alternator to the block had broke in two and the alternator was holding on by the adjuster bracket only.

Broken bolts typically aren't a huge problem, but my drill bit won't even make a dent in the bolt so I can fit the EZ out in. I guess the bolt is hardened. I've tried a couple grades of drill bits and they don't bite either.

Any thoughts on how to drill a hole into a hardened bolt, or other ways to get this bolt out of the hole? I've thought about trying to weld something onto it, but don't own any welding equipment, or know anyone that does.

[JimN]

Sears has bits that are coated with Titanium Nitride, and they cut into very hard bolts and metals. I have also used Black and Decker Cobalt bits with good results. When you get it out, don't use a grade 8 or anything that hard. You'll just be doing this again. Use a center punch to mark the center before you start drilling.

[lakes Rick]

I purchased a set of reversed drill bits... Wow do they work nice for getting out broken bolts.. Not titanium nitrade so might not work for you...