I believe that that is the side that the power steering pump is on. These, ans you may know, have seals that leak. Even re-sealing the unit may only be a 30-60k mile solution, requiring re-sealing again.

So - your power steering fluid may be low - have you checked it?

It's interesting - the radiator has rubber flaps on the back to keep hot air from blowing on the P/S pump at low speeds or at stops. At higher speeds - these flaps open and allow cooler air to pass over the P/S pump (but the air still comes though the radiator). I doscovered this when changing my oil one weekend. It tells you what a challenge heat management is with the M119 / W124 setup (I have an E420).

Let us know what you discover.

Troy
1995 E420 75k