How hot is too hot for engine exiting coolant?

[cgrey8]

As mentioned in other threads, I want to work on a way to get better cooling from my pusher fans because I'm concerned about my temp gauge going pretty high into the "NORMAL" range when sitting in stop-n-go traffic with mild weather temps. This morning, I took a thermocouple and measured the temperature of the upper radiator hose while the engine idled and maintained the gauge at the "A" in "NORMAL". My meter indicates the temperature is floating around the 195-205°F range. The value bounces around a lot. I think I saw the value bounce up to 207°F once. However 205°F doesn't seem unreasonably high for a relatively new engine (97 Explorer 302). But how hot is hot enough to get concerned about engine damage? I've seen some factory temps that indicate 225°F is still in the normal range, but that was also on a GM, not a Ford.

Another interesting find is I don't get really hot air from the ducts. My old 2.9L ran a 180°F thermostat and always ran very cool on the gauge even with the 1-core radiator. I installed a hotter 192°F thermostat in the V6 and the gauge went up a tad, but not considerably. I realize I'm not using the same coolant temp sending unit on the V8 that the 2.9L had so I'm not comparing apples-to-apples but my point is my 2.9L used to give me very hot air from the ducts even with the 180°F stat. With the V8, I can run the climate control all the way over to the red, and I get moderately warm air. I haven't researched whether I have a heater core coolant flow problem or a cable/damper problem in the cab. But being I haven't done anything with the dash other than stereo work, I can't imagine the climate control dampers are at fault. Anything's possible though.

I thought I'd throw it out there for discussion...