broken bolt on thermostat housing

I was replacing my thermostat and one of the thermostat housing bolt heads snapped off on my ratchet! I'm left with about 1/4 inch of thread. I've tried channel locks and vice grips...to no avail. Does anybody have any ideas? I swear I'm cursed when it comes to this car!

I did the exact same thing. I tried a drill out extractor - it broke off in the bolt. What I did was tap threads in the block...#8 or 10 or 12 size bolt (can't remember)...right beside the original bolt hole. I adapted the housing with a new bolt hole to match the tapped threads. Use a gasket and permatex on both sides of gasket.


See the keyhole on bottom left of my housing - right side of it is the new bolt hole.

http://home.comcast.net/~dougand3/tstathousing1b1.jpg

Soak the broken bolt/stud with PB Blaster or some other penetrating oil for a day or two. If you can get a grip on the bolt with vise grips, try tightening the bolt to break it free, about 1/32 of a turn or less (before loosening). Otherwise you are going to have to drill it out. When putting in new bolts, use anti-sieze compound on the threads.

If you can get on it with vise-grips try tapping the vise grips with a small hammer rather than trying to torque it out. A series of small taps rather than trying to twist it out is the key. I'm afraid a strong steady pull will just break off what you have left. Then you'll have to drill it out.

Hi soak area with seafoam penatrating spray, Take torch heat around broken bolt, now this spray can be used on heat great stuff spray after heated use a very good pair of vise grips as you turn spray a little more, working the bolt i found helps also so while turn this broken piece out you can go in and out this allows the seafoam to coat threads so you don't chance a helicoil.