I was attempting to remove the neck of the thermostat so I could change it. One bolt came off easy, the other, not good, it was really tight inside. I soaked it in liquid wrench and tapped it with a hammer multiple times. I got half of it out, the other half about 1/2" broke inside flush with the top of the intake manifold. I center punched it then chased it with bits up to 1/4". I hammered an EZ out in but still couldn't get it to come out. Also, I got a hair off center and wondering if I might have drilled into some of the threads from the intake. There's a thin wall of the bolt left on one side and about 1/8" on the other. Any suggestions on this one, I don't want to break the EZ out inside!!!