Hi I had 2 W208.. I changed the pump in one 2 times 2 times ...check the condtion of the hose if it's mashy or cracked better replace it ..these pumps tend to become loud when they are near failure ...my 320 had the orignial pump and I sold it with 260,000 km's on the clock ...I put an aftermarket in my 430..it failed after 5 months.