Advice needed W126-engine noise

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.

[dpetryk]

I have the same problem except it only occurs when the car is cold. I hear it mostly at low RPM's. A kind of spooky howling sound. Maybe the car has the halloween spirit. Im sure its a bearing on the front of the engine which includes; water pump, AC compressor & idler, Power Steering pump, Alternator or air pump. I have not been able to figure out which one it is. Might just have to wait till it fails. I was going to get a stethescope and see if I could find it that way. Im just praying its not the water pump (again).

[MikeTangas]

OK, you kind of hear this noise at low speed and really hear it above 2500 RPM? Try this, with the engine off spin the fan by hand, does it turn with some resistance and spin for one rev or so or is it real stiff and hard to turn? Next start the engine, listen to the fan, while listening closely bring the engine speed up to 2500-3000 RPM, did the fan get quiet? It should have, if your's isn't, it sounds like a visco fan clutch gone south.

MikeTangas:

Thanks for the tip. I'll try it tonight.

I do recall the fan spinning without much resistance with the engine off.

As I said, the noise [whirling and overall engine noise] is in concert with the thottle. In order words, it gets louder as more throttle is given, and it goes away as I decelerate. Does this point to anything specific?

Thanks again.

[goldenbear]

...but, are you loosing any coolant? The symptoms you are describing are similar to those I experienced when my head gasket was beginning to fail.

Worn distributor drive?

Mine seems to be the air pump.

Ray