David,
Nice little post; some nuggets of good info in there.
Why should I believe my temp gauge? Because its never lied to me before? Actually, I have a non-contact thermometer, but don't know where to "stick it" to accurately measure the temp for comparison purposes.
The "crusty stuff" I mentioned - according to a source I accepted - was hard water mineral deposits from tap water (I now have distilled water along w/ my coolant). I suppose it could have prevented a good connection somewhere else.
Unfortunately, I don't know where the temp sensor for the gauge is, actually. At this point, I would clean grandpa's butt if it would solve my problems!
Did changing my thermostat help any? Sadly, I'm not really sure. I replaced it, but still seemed to run hot. BUT... I did not let the car get over 212F before shutting down. It's possible that the thermostat DID help, but I hadn't properly burped the system. (I've never had a car that gave me a problem over "burping" until this one). I CAN tell you that the car has not gotten hot the way it did that first night. The system has never boiled over; and that night - when the gauge read close to redline - I was able to open the cap w/o so much as a hiss after waiting half an hour.
I will have to try to see the fan come on to know if it is spinning the appropriate direction (I presume it should spin in the same direction as the engine fan?). Until the last several days, I was not using my air at all, and was not the night the car ran hot to start my problems. Generally, the climate control system (believe it or not) keeps the car cool enough that I don't need to turn on the compressor - even in Palm Springs. The air blows cold when I DO turn on the compressor.
At this point, my problem may basically be fixed, and I'm just being paranoid (they ARE out to get me, after all!
). But it seems to me like the car is running about 15 degrees F hotter across the board than it was before this happened.