Yesterday I replaced the DEVIL's THERMOSTAT. I should have checked to see if 666 was stamped on it somewhere. I guess I had it coming, penance for an unclean life when I was young :^)
I just wanted to replace the coolant and thermostat in our 93 Taurus. Since I was using a newer 'extended life' Prestone, that's what they had on the pallet at the place where I buy such things, I bought two gallons so that I could flush the old stuff out. The old stuff wasn't too bad, no rust or anything, but it was getting to be about 2 years old. The car tended to run hot in some situations since the dealer worked on it, getting to 2 o'clock on the temp gauge, so a new thermostat seemed in order. Everything went well until I tried removing the 2nd and 3rd bolt on the thermostat housing, where the heads just popped off with little effort. Groan, quiet curses. I got the housing off, and after an hour of tapping and soaking with penetrating oil one of the studs came out. The bottom one, which was hard to get to because of a large wiring harness, broke off flush instead of coming out. Loud curses with flung wrench. An hour of drilling, checking, recentering with a Dremel and carbide cutter, drilling, I managed to end up with an oversized hole. Deep in the hole of depression, I took a break and rumaged thru my toolbox, looking for my taps, when a light evidently from heaven itself illuminated a Helicoil kit that I've been carrying for over 20 years, a kit with inserts for the size thread that I needed :^) They were shorter than I wanted but I managed to get two in the hole. Everything went back together quickly, and so far the car runs cooler than before. The old one didn't seem to be installed correctly as the 'jiggle valve' wasn't up, but I don't know if that would affect running temperature.
I hope for no more excitement from my thermostat, and continue my praise for good tools.