M103 water leak
 

I have an 86 300sl and I've developed a water leak and found that it's on the bottom of the oil filter support. There's two connections,one going inside the car to the heater and the other which is the one that was leaking had a rubber cap on it which was deteriorated. Should this be connected and to where? It's not running hot. My paper work that I got with the car said it had a waterpump replaced but that it had to be modified somehow to fit the European engine and my mechanic said there's no difference in the two. Thanks and have a Happy New Year! Greg.