Hey Ramachez,
If you look inside the reservoir with the engine running does it look like the fluid has air in it? Believe it or not, I just did one of these, and Mercedes sells an updated "O" ring between the pump and reservoir, the old one leaks air into the system which makes noise, replace it and the problem should go away.
Here is the video
https://youtu.be/uYaY-JeJWYQ
Please let me know what happens
Best, Ken
SPONSORED LINKS
Wednesday, October 7th, 2015 AT 3:58 PM