This is a dumb project. The old car had a water temperature sensor that leaked a little and was wildly wrong. It read like 220F all the time the car was running. It often read 100f when the car was off. So I got a replacement, calibrated it, and that sensor leaked like whoah. I tried a LOT of things to seal it, o-rings, spacers for more clamp pressure, pipe dope. This is the current iteration, a condom, with tapered threads where it screws into the head so they'll seal.