[MrNeon2000]

Recently I have purchased a 1990 300E at 75k and have put on 10k more since then.
The car seems to be running at 80-85C while driving on the freeway but the temp goes up in slow traffic and at idle speed. I usually see the indicator go around and above 100C. For instance if I make a quick stop at a parking lot and come back to restart my engine, indicator seems to be above 100C. It cools down as I start driving but it worries me that it gets this hot.

I have recently got a new radiator and had the cooling system checked for any potential leaks. (no leaks found). I am suspecting that the thermostat switch is on the fan might not be working thus preventing the fan to kick in (?)
I appreciate your suggestions.