Anything can fail, it doesn't matter who made it. In the manufacturing industry it's called "Infant Mortality Syndrome" meaning there's a bathtub curve associated with an increased failure rate when new, relatively steady low failure rate during normal service life, then an increased failure rate when aged out.

To confirm it's the pump, drop the belts. If the noise stops, you know it's probably something in the auxiliary drive system. If it doesn't stop, you could have an issue with the vacuum pump, idler sprocket, chain tensioner, or timing chain.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]