i have a '71 220d that is leaking oil. however, the leak is coming from what seems to be a large bolt located on the front, drivers side of the engine in front of the injector pump. the bolt head is facing up and it is recessed into the block, and in this recessed area the oil is pooling and dripping down the engine. can i just tighten this down to stop the leak? what is this for?

 

i will try that, thanks. im not sure if there is a specific forum for older mb's, so i will ask my next question here although it is not diesel specific: my speedometer is not accurate, how can this be fixed? it seems as though it is reading 10 mph lower than i am actually going. is this common on these cars (220)? thanks