Foreign Mechanic help?

today i was trying to switch head units in my 87 mercedes 260e and i noticed all the wires where covered in some kind of fluid. i think his is the reason why my eclipse head unit pretty much crapped the bed. Over the last year and half it would only play cds every now and then and since yesterday it would not play any music or radio what so ever. today i tried to see what it would do and it was flashing not letting me turn on or do anything just the screen flashing with all the buttons. I pulled the head unit to replace with a different head unit and noticed the whole top of eclipse had some kind of fluid cant tell a color. It a way it smells kinda sweet and sometimes while i drive i smell a sweet burning smell. I recently had the head gasket replaced and was told my radiator is clogged to flush or replace cause there might be a bad transmission cooler. The car only heats up when i come to lights or stop but while driving it seems to be doing fine. does anyone have any ideas what could be leaking and would it not be safe to put a new one in the time being? also one last note the last couple years i only had volume on the front speakers and could not hear any from the rear would this have something to do with the fluid? any help would be greatly appreciated