I solved my engine rattle mystery
 

Evening,

For years I have stood before my 190d looking at the engine while running trying to figure out where in the world the rattle was coming from. Close as I could isolate it was around the water pump. While standing there the other day doing the same thing over again I noticed that the small shock to the left of the spring that tightens the belt was wearing quite a bit at the top bolt. I ordered a new one, and put it on. When I cranked her up to see if everything worked O.K. all I could hear was the smooth sound of my engine idle. No rattles any where. It's hard to believe that that shock caused all that rattle noise. I guess the inside parts were worn, and they just shook around in there.

Hugh Sr

1984 190d 95,384

This is VERY common amongst om60x engines. Usually the bushing(s) on each side of shock wear out and rattle. Very satisfying fix!