Re: headgaset in a bottle, 97 Legacy wagon:
Fininshed the process last night and drained the stuff out, and let it sit. It might have been a little COLD last night, but didn't have much choice.
Filled it with water and put the 'plates' back on (Hey, it the same plate, and there IS a sort of valid registration...) and drove it for about 15 minutes, and the temp guage stayed rock-steady. On plain old water...
Maybe this did the trick...