does anyone know the thermostat housing bolt size broke one while making it snug? cant find much info in google other than what i saw on the bolt marking a saying that it was a grade 5.2
Why so tight? Trying to stop a leak? Maybe your bolt is bottomed out before it actually clamps the water neck.
My recommendation is to install studs with anti-seize, then nut down the water neck.
The threads for water neck were broken out in mine so I also installed helicoils with red loctite. They are a great repair and are actually stronger than the original threads. Careful with drilling and tapping for repair so you dont break through and end up with water leak.
For studs I used grade 8 bolts, cut off the shank, and cut a notch in end for flat blade screwdriver.