i have recently become the proud owner of a 1990 190, 2 litre diesel. Its my first mercedes, and although its a little slow, its been doing me very well until quite recently, when it began to lose coolant, and get hot!. I finally traced the leak today, to some sort of bolt or nut on the side of the engine block, just under the exhaust. Is my enginre dead? can I fix it? i'm not completely inept as a mechanic, but ive only ever worked on motorcycles and not cars. It doesnt look like a core plug, I'm hoping its just a loose nut, but advice please, asap, im stuck at home !!

Block drain, perhaps?

I was thinking block heater? Does it look like you can plug a cord on to it or is there one there now? Anyways you probably do not have a major problem. Just do not get that engine too hot. Then you might. Fix the problem now if engine is still running good. I do not know the location of the block heater on that particular type engine.

I would like to thank those who took the time to offer advice and help with my problem, both of you! The helpful tip from Matt L was particulaly well thought out, and not at all designed to make me look stupid, or him so clever. As a point of interest, the drain plug was about four inches towards the front of the block. I have fixed the problem with the application of half a tube of fast metal, and its running sound again. Thank you