My '95 nonTurbo 945 had the radiator replaced about 2.5 years ago. About a month ago, I had an unusally failure. I was travelling on the turnpike relatively high speed (80-85) on a very hot day (95F) when I lost my cooling fluid. Pulled over and noticed that there was a plastic plug on the top side of the radiator that had blown out (right near the battery). I couldn't find the plug and had no additional fluid anyway, so I towed the car to the shop for a quick fix (new plastic plug and fill). I did not notice any high temperatures on the guage before it blew off (I wasn't really looking, so it is possible it was high). I had my mechanic get extra plugs, just in case.

Well yesterday, while driving again on the turnpike at similar speeds, it happened again. This time I was watching the engine temp guage at the time by chance and it was in the normal range (slightly above half scale). Found the plug, filled the radiator (put a gallon of fluid in the back just in case). The plug seems to fit in the opening relatively loosely, like it couldn't hold much pressure, but beside for these two incidents (which of course is two to many), it has held.

From reading the FAQ, it appears that this plastic plug is in place of the temp sensor (which my car doesn't have). Can a better plug be fitted (or even epoxied) to this openning. If so, where will excess pressure be vented?

Thanks in advance for you assistance.