I believe there is a short section of hose that connects the water pump housing there, it will have hose clamps on each end but since that engine is SO GUNKED UP its really hard to see anything in the pictures. The squirt in the movies tells me you do not want to drive that car anywhere until its fixed but you probably already know that!
If its that hose, the dealer is a good source but be aware they sell in meter lengths, not the 4 inch or so piece you may need
Use some WD40 to spray around in there and some elbow grease with an old toothbrush then rinse off with a thin stream of water from a pressure hose and it will look more like working on and you'll be proud of how clean you can get it before doing the job so less dirt gets on your hands (you do wear gloves to work on it don't you?)

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!