Trying to remove my thermostat I broke one of the fastening bolts. Snapped right off. Just one tired and stuck bolt...
Now I'm stuck with the remains still sitting in the block. All efforts and chemicals wasted, I now have to ask for advice.

Has anyone solved this problem in a clean and decent manner?
Like drilling it out without destroying the seat in the block....

Any advice much appreciated!!!

 

I had the same problem before with the head of the bolt to the thermostat houseing broke off on me(If this is what U are talking about), I was told to use one of those drill bit extractors, but believe it or not, I got mine out by getting a pair of Vice grip plyers and squeezing that sucker on there as tight as I could and then started turning it, and beleive it or not, IT WORKED for me!, slowly but surely.. Just a suggestion....thx....Coop

 

Ouch! There is so little room in there to work with. I don't know about the 4.0L, but the thermostat housing on the 3.0L is on the lower intake manifold. If worse comes to worst, you can remove the intake manifold and take it to a machine shop. They will drill it out for you without ruining the thread on the intake manifold. But that's the last resort and probably very bad advice.

I'd suggest soaking it with tons of chemicals and try the vise grip thingy first. If that doesn't work, you can try drilling a hole and use the stud extractor. If that doesn't work, just drill it out completely and buy the heli-coil thread repair. Also, replace the current bolts with stainless ones and coat them well with some non-hardening sealant so they won't rust like that again.

Good luck.