Went to replace my thermostat and the bottom bolt snapped on me. When I went to drilled it out to extract it I accidentally drilled all the way through and the hole no is above where the bolt was. Is there anything I can do to fix this or am I screwed?!?!

Thread sealant. It's normal to use the on small block Chevys since the head bolts go into the coolant jackets.

The hole completely screwed up the threading on the hole for the bolt. Thread sealant wouldn't be strong enough to drill through or rethread the original hole would it?

If you heli-coil it right, it will be like any other thread.

search youtube for helicoil

Ouch! That hurts me just looking at your post Scrawn. A nightmare. It only needs to hold the pressure of the clamp on the hose, less than 20 Lbs.

I might thread the hole, wherever it is, then file, customize the T-stat housing to accommodate the new hole position. Having it straight will of course bring the washer down flat on the T-Stat housing. Even go out to 3/8" if you need. Also you might "alter" a washer if need be. Then a "tender", job, let the let's say Blue RTV sets overnight, just snug, before tightening carefully a bit more the next day.

If your housing is ugly, maybe invest in a new one, up the chance it will seat clean.

Gads, those easy things can be a real headache!

Yup.

This is the best option for what you have done and follow the directions on it when installing.


FYI I make a small jig when I need to drill out a bolt so it goes straight if its iffy to get to.