Dear Experts:

I have a 300SEL 1989 with 80K with a typically louder than norm engine noise.

When the car warms to operating temperature and travels above 45mph, a certain whirling sound comes out from the engine bay area. The sound is more pronounced and is in concert whenever the throttle is applied above 2500rpm. The sound descends over the entire cabin and dominates an otherwise quiet vehicle.

I note that travelling at a lower gear, say 2nd gear, when climbing a hill provides a similar noise.

Sounds like a fan spinning, but then it could possibly be from exhaust. In any case, it comes from the engine area.

Maintenance wise, I have recently changed to 10w30 and performed basic tune up, e.g. plugs, cap/rotor, coolant, tranny filter/ATF. Fuel filter to be renewed this weekend.

I know that I haven't given too much by way of clues but any help will be greatly appreciated. Perhaps a fellow member may have had a similar experience.