I agree, but I want this to be the fix. The trouble now is draining all this new coolant and some how putting it back into the car once I have replaced the thermostat, if in fact its bad. As I mentioned I plan on placing the t-stat is a pot of water and see at what temp, if any, it opens. I have heard of this test, but have never done it. How much should a good t-stat open?

Since I have never dealt with a reverse flow radiator before, should I have been able to feel a fair amount of heat going through the hose that connects directly to the t-stat.

In a traditional t-stat set up, once one felt the upper radiator hose get hot, that meant the t-stat opened. This as I said is a different animal.

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1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member