Broken bolt on thermostat housing
 

I was changing the thermostat housing on my 01 Blazer. All was well until the rear bolt snapped while removing. I've tried vise grips, and even drilled into the bolt for an easy out. that was going well too! Until the bit broke off in the bolt, so I tried a Lisle broken bolt and stud remover socket set. I got a good grip on it, or so I thought. It only stripped the piece I was grabbing. I'm now at a loss, dunno what to do next. Any Ideas?

I had the same problem as you about a year ago when I changed the thermostat on my '01. The front bolt loosened relatively easily. The rear would not bulge. I gave it a little more force (just a little, I promise, on a 3/8 ratchet, no cheater bar) and it snapped! Like you, I tried vise grips and extractor to no avail. I even went to Sears and purchased "Bolt out". This did not work either. So I just put it back on with the one front bolt and it does/has not leaked for a year. Yes, I was shocked. A month ago I did a needed LIM gasket change, and since the manifold was off the vehicle and more accessible, I again tried to remove the broken bolt to no avail. I put it all back together and no leak!

I not officially telling you to do that, but, it has worked for me for a year.

a little heat and penetrating oil go a long way

Left hand drill bit and an easy out, (usually come together in a kit). If you're lucky, the bit will grab the bolt and back it out while you're drilling. If not, after the hole is drilled, use the easy out. Done it that way several times, most of the time the bolt backs right out while drilling... gotta use a left hand drill bit though.

Send a pic and I or someone else will walk you though how to get it out.

Working on older cars, I've broken even the easy out off in the bolt. Takes a bunch of patience to re-drill through the easy out or drill bit as they are harder than hell. Need to find a drill bit that's very hard, not a standard bit. The bits I ended up using I bought at a state fair, where they drill through metal files and other hardened metals, but still took time. Heat from a torch, PB Blaster, and spray freeze helps too, AFTER your hole is drilled that is.

I hate easy outs I always build a weld above the stud and weld a nut to the top and get it hot then it comes out every time

kinda funny, i am dealing with this right now on a 87 c10

I'm having a problem getting a broken bolt out
 

I've been fighting with this for days. the bolt broke off too low and we cant weld anything to it. My "mechanic" came hammer and eazyout to it but the bit broke off as expected. We've been trying to drill into it for days now and have barely gotten anywhere. I'm in desperate need of assistance.
https://cimg3.ibsrv.net/gimg/blazerf...1226758e4.jpeg

There are a few different methods. Start at 10:45 for a very good one:



George

A closer view:



George