I've been able to fix a few problems (broken hood latch, etc) with my 1992 190E by searching the forum here, but I've got a coolant leak I can't seem to diagnose and a search has brought me nothing.

I found this thread from a couple years ago, and it sounds similar to my problem, but no one responded to it.

I'm having to refill my coolant every week or so and we've already ruled out the water pump (the leak is definitely coming from back near the tranny), and I thought it might be the heater core, but there's nothing leaking inside the cabin.

Any ideas guys?

Try replace at heater valve and the heater hoses first since they are cheap! Sometimes, heater core leaks, which is not leak inside the cabin. If replaced heater valve and hoses, still see water leak out on the back of the engine area.... I will say heater core leaking.

Replace heater core on 190E is easy... about 6 to 7 hrs job. Just need to take out instrutment cluster, steering wheel, whole center console, dash. Then, only 4 nuts to hold up the heater box. Unclip the heater box and you will see the heater core.

There is the heater valve that is under the cowling between the firewall and the windshield. It is on the passenger side with two hoses and a red vacuum line going to it. You may be able to peek through the cowling with a flashlight to see if it is leaking. If you cant see it, then pulling the cowling up isn't too bad.

If your heater core was leaking I'd expect it to fog the windshield on defrost.

You didn't mention if you have a 2.3 or a 2.6. On my 2.3 the hose at the rear of the head on the drivers side became soft and started leaking. You might want to check it...it could be trickling down the bell housing and dripping from the transmission.

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1993 190E 2.3
2001 SLK230
1971 LS5 (454) Corvette Convertible