Please tell me your reasons for replacing the water pump on your '94 S500. What is leaking or making a noise? If a noise, can you please describe it?
I have a problem with my 1992 M119 5.0L engine as well. I believe it to be my water pump as well. Mine makes a load whirring type noise when the car is running (much lounder when the car is cold).
I pulled off the serpentine belt and started the car. The noise was completely gone. I've replaced ALL the belt-driven accessories in the last 180 days EXCEPT for the water pump. I'm suspecting that's what it is.
Also, where did you find one for $80?!? I'd like one too for that price!!!