[rdorman]

Do you have a closed system Chifo? My system does a pretty darn good job of purging air all by itself. In the warmer months I run nothing but distilled water and water wetter.

The car did run hot on occasion last summer at DVSFII. I flushed the system (ran super flush in it for days), drained the system, filled with water wetter and distilled water. With the fill cap off and engine running I continued to fill the system until the thermostat opened (I also measured the water temperature at that point to see that the thermostat was opening at the correct temperature. Even if it says 180, it may not open at that temperature. This is certainly easier than removing it to test. My system fill point is just inches downstream from the thermostat), replaced the cap and shut it down. I then completely filled the recovery tank and checked the level occasionally over the next several days. I could see that the system pulled in a little more water each time I drove it, then the level stabilized. I am not saying this will help you, but it was all I needed to do.

Oh, I also set the fan temp at the same time I was checking the thermostat and filling the system. Before I started it I turned the adjustment to the higher temperature. I verified that the thermostat opened at 180, let the temperature rise to above 190 and then adjusted the fan to kick in at that temperature.

I would still pressure check the system, ensure the cap is sealing well, test the cap, thermostat opening temperature, fan start up temperature and polarity. If all that is good, measure the head temperature at various location, writing it down, to check for even cooling. Realize of course that the temperature will vary at different locations but look for consistancy. If the head temp near the exhaust port is the same across the board, great, if not....... . While you are checking temperatures, you might check the header temp of each pipe, especially as the problem occurs, to see if you might have a fuel issue.

Running lean at cruise may fit your issue. As would timing.

If not, head pulling time!

I am eager to hear how you resolve the issue so please keep us informed!

Rick