Have you had the tech that installed it look at it. MB suggests the relay because the current carried to the pump, especially on leaking cars, fries the relay (and sometimes the wiring).

You shouldn't be able to hear the pump so if you are it is likely mounted solidly instead of on the rubber cushions designed to isolate the noise.

The 2000 modles should get new struts in front most likely as they were redesigned. There is also a bulletin for resealing the valve at the top of the strut. If you don't fix the leaks you will be replacing a lot of pumps.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician