This is a brand new Genuine Mercedes check valve for the fuel injection pump on 4 and 5 cylinder diesels 1977 to 1985. This valve is mounted on inside of pump in the fuel line going to the filter. When it fails, fuel will leak back down into the pump causing slow or rough starting primarily when the engine is cold. This is due to low fuel pressure and air in the fuel lines at initial start-up.
PLEASE NOTE: This checkvalve will look different from what is currently on your engine. Mercedes has changed the design, but this new valve will work just the same. In fact, we have two types with just a slightly different head. They all work the same. The newer ones are sealed but do NOT be concerned about the different in design!
This check valve is located on the inside of the injection pump (center of picture above) facing the engine block. Return fuel leaves the pump through this filling and up to the top of the main fuel filter.