Not sure if this is the right section. Over the weekend I flushed my cooling system and replaced my thermostat. It was an easy job until I realized that the reason the prior gasket had been leaking was because the bolt hole was stripped. So I drilled, tapped, and put a helicoil in the hole. Well it turns out that I didn't drill deep enough and the bolt stripped when I tried to torque it down. How do I fix this? Should I drill and tap for a bigger bolt? Can I just use a 3/4" long bolt?