I'm driving a 1979 245 Wagon. All of a sudden, this past week, the needle in the temp guage has risen almost all the way to the top. It stops just short of the "red" zone, maybe a needle's width away but never goes any higher. My first thought was the thermostat, but a new one didn't solve the problem. Driving with the heat on doesn't bring down the temp either. There are no leaks and the coolant is up to the proper level. There are no unusual noises either when driving. I have been suggested to put a cooking thermometer in the coolant to be sure that it really is overheating but where should I stick the thermometer. There is no cap on the top of the radiator. In the fliud resevoir? Do I need a special temp guage? Any other ideas?

Phil - Vancouver WA

P.S. As this is my first visit, I must say that this site is a life saver. I've had 3 other of my questions answered by looking through the archives before this posting. Thanks to all who frequent these pages!!