Merry Christmas All!

I have a 1993 190E 2.3L. It has been having this slow coolant leak for two weeks now, and had just topped it up twice. I finally got a chance to look under the hood and watch for leaks.

From the passenger's side, I can see an open black hose approximately 3/4 inches in diameter, pointing down from the engine (haven't gotten under the car yet), behind the alternator. It only seems to leak when the engine is running, so I am not seeing coolant loss when the car sits.

I can't get an appointment until after Christmas, but I was wondering if anyone knows what this hose is and where the coolant may be originating from?

Thanks in advance for your input. Earnest