After few days, I finally found out the coolant losing on my 1995 Mercedes C220 M111 engine.

It seems one of the freeze plug shows coolant leaking out on the back on the engine. Little coolant shows on the top of the transmission bell housing. It doesn't look like leak from head gasket (no coolant and oil mixed, car no burn oil, no burn coolant, no any oil leak shown on the oil pan).

Anyone has an idea how to replace that freeze plug on the rear of the engine?

Do I really need to drop off the transmission to replace it?