First some details.
1. I'm running the NEW Plastic Header Bottle DMCH sells, this allows me to actively SEE the coolant level.
2. There is an Auto bleeder in the system.
3. New (2 year old) 15 PSI Cap.
4. I run the DM-eng (SMART FAN RELAY) The Fans will continue to run or delay shutdown for 20 seconds after switched signal power has been turned off. ( Otterswitch cycles off, mode switch turned off or Key off when fans are running at the time of shutdown).
5. The engine was stone cold with the coolant level at the MIN COLD coolant mark or about 3/4 empty.
6. I fired it up and let the engine idle warm up (about 800) rpm till the the Fans came ON just shy of the 220 mark.
7. At about the 205-208 point (w/temp rising) the Expansion tank Air volume had been displaced by coolant and starts puking out the overflow.
When the fans came ON the coolant level began to recede just enough to stop the puking. I waited a minute or two to see where the level would settle at. Unfortunately, I had to cut the run short and shut the engine off at 200-205, before the Fans had cycled off normally. The Coolant level at shut-off time was just below puke stage. Immediately following shut down (Fans running 20 seconds) the level rapidly recedes too 3/4 full level, I just checked the Cold level this morning and it is now 1/2" below the MIN COLD line.
I am intentionally leaving out one important detail which I'll tell you later, because I'm interested in what is considered NORMAL coolant level fluctuation with temp variations. FWIW: My Normal at speed driving temps are just above the second mark. ( I run a 192˚ thermostat) At that temp the coolant level will typically be at 1/2 to 3/4 full depending on starting level.
I also realize most folks on here have converted to a none viewable (stainless or aluminum) header bottle which makes it difficult to gauge the operating levels. (1 of the reasons I don't like them)
I await your replies.
Thanks