Sorry, I don't do instagram.
Okay, so you're saying you have a 185 degree thermostat.
I'm seeing various thermostats sold under the part number in the manual for the 6.2l HMMWV as either a 170 opening/180 open or a 190 degree open depending on who is selling it. So the 185 isn't really a lower temp thermostat. Still within the range I'd expect for this engine. When you said lower temp, I thought you were talking like a 165 degree thermostat or something like that which could have an impact.
And yes, I understand how a cooling system works. The coolant inside the engine block heats up, and once the coolant gets up above the opening temp of the thermostat, then the thermostat begins to open, allowing coolant from the radiator (which should be at a lower temperature at this stage) flow into the engine block. Until the coolant in the block is at or above the fully open temp of the thermostat, it's only partially open, restricting flow.
Once the thermostat is fully open, the coolant circulated freely through both the engine block and the radiator. As it travels through the radiator it gets cooled by the air flowing through the radiator area. It should be at a lower temp by the time it exits the radiator back into the engine block.
The temperature of the coolant inside the block should remain constantly at or above the opening temp of the thermostat. Is your 185 degree thermostat just beginning to open at that temp, or is that the fully open temp? I'm wondering because with the high speed fan switch on the engine, rather than the radiator, in theory the high speed fan turning back off at 180 would mean that once it kicks on, it should never turn back off until the engine is shut down and has a chance to cool off. Not saying that's what is happening, but it does make me wonder. I do like the low speed fan sender being on the radiator itself, as it doesn't matter how hot the engine coolant in the block is if the radiator is full of cold coolant it doesn't really need cooled any further.