Don't know much about the 190, but isn't there a coolant pump that is supposed to circulate the coolant after engine shut down. If the 190 has one of those, I'd check there, perhaps a hose is brittle and releases minute or even more coolant at a crack.
Again, not sure if the 190 has that pump!

__________________
Mostly, I don't know notin, I just know where to look.
I am looking back, to over 30 years in Electronics Design.
Electrons don't care if they move in a car, computer or relay!

95 W124 E320 M104.992 - Because, I love to repair, naaaah!
Over 221,000 Miles
Cheers,
Norbert