I have a 1994 E320 sedan and have noticed a hose that has a bubble in it. It obviously needs replacing. I am not sure what the hose is and have been unable to find a picture of the engine components labeled. I will have some manuals soon and then I can identify it myself. Anyone have a picture with hoses labeled?

The hose is on the drivers side, (there are two of them one over the other) the hose has factory fittings, and I am guessing are fuel line or coolant hoses. They come from a small brass colored cylindrical unit on the drivers side and go to the engine on the drivers side. Only one hose is compromised should I change both anyway?