My truck has not been heating up so I figured it was the thermostat. Well my quick 30 min job is still sitting in my driveway. I got the first bolt out but the second well it decided to come apart. Lucky me.

Is there anything I should worry about drilling and tapping the hole?

 

I always feel better getting a second set of eyes on stuff like this. I'm a good mechanic but the fog of anger and frustration sometimes limits my perceptions and then sometimes a good friend will have a better idea that would have never occurred to me.

 

Trying to drill a steel bolt out of an aluminum manifold is a right PITA. Center punch the bolt as close to center as you can, then start with a SMALL LEFT-hand drill bit, and work your way up in size. Eventually, the drill bit should back the bolt out. Or, if you have a welder available, weld a nut to the top of the bolt, and use that to back it out.

 

The left hand drill bit is a good way to go, That way if the stud lets loose it will back out as it grabs. Make sure you start the drill on center of the stud with a smaller drill, a center punch can help. You have the replacement option of a threaded insert, heli-coil, or tapping a larger thread. Get a stainless steel insert or heli-coil so they don't rust if you go that route.

 

The idiot who replaced the thermostat in my truck before I bought got gasket sealant all over one of the bolts. Needless to say the bolt snapped. Had to drill it out. We tried backing it out with a left handed bit, was no use, as the bolt seemed to have welded itself in place. So we Drilled the bolt out, retapped the head, installed new thermostat. No leaks been working great since.