I just bought a 2002 Durango SXT 4x4 with a 4.7 and 50,000 miles.

Last night I noticed a whining sound from under the hood. At first, I thought transmission problems. I stopped and put it in neutral, revved up the engine and still heard it. It is definitely under the hood. The whine is barely audible at idle and gets increasingly louder as the rpms go up.

I found an old posting on another site that sounded similar, but no final resolution was reached. The dealer blamed it on the alternator which was on backorder at the time. This guy described the noise as sounding like a power steering whine when you are low on fluid, which is close to accurate in my case. My description is more like electrical noise through your car stereo if anyone has ever experienced that. In fact, I checked to make sure the radio was off just in case. There is no growl or roughness in the noise. It is a smooth whining sound that increases in volume with the rpm.

Everything appears stock and relatively untouched under the hood. No performance upgrades that I can see. I don't think it is anything major, but even an alternator going out on a vacation can be more than an annoyance.

Any ideas or similar experiences?

 

I had the same thing. It was the tensioner pulley.

 

I second the tensioner pulley. Replace the whole unit.