Coolant leak
 

I have noticed a coolant yellow) leak under my transmission. It appears to be coming from the cover plate, I tightened all the bolts but still have a small leak. Is this cover for coolant only? I see no transmission fluid (red) leaks.My Benz is a 1989 190E

Leaks in the rear are often caused by leaks in the front being blown to the back. Also, the belly pan can mask the actual location, too. I would first check around the water pump, and then check all coolant hoses and connections, including the heater hose going into the firewall.

The only coolant leak thgat might look like it's coming from the transmission would be a heater core leak from an interior drain hose. I am not sure but I think it may come from the evaporator drains if the core is leaking. Do you smell coolant inside the car or are you getting steamed windows?
I agree with the previous post also, it could be blowing back from the engine area.
Best idea I can give is to pressure test the system with the engine cold (1st thing in the morning) and watch for drips. (UNDER the car, not on this website, LOL!)

Gilly

LEAK
 

Great suggestions by both. I looked where the leak was in comparison to the fire wall as you suggested and dicided to check the hoses to the heater aat the firewall. They seemed ok then noticed that a leak was coming from the heater control. Thanks very much. Problem solved.