I just noticed last night that my car sounds like this coming from under the hood. A friend of mine told me it was cuz everything was cold due to being outside, but even though it's been driven around for a while with the temperature higher, it continues to make this noise. Here is a video recording of how its sounding. http://www.youtube.com/watch?v=AqI8aIWFk4s

(The squeaking and everything is more loud and obnoxious in person)

 

oooo, i may have the solution to your question, i had the same noise and it was actually the vicous fan manking the noise, the fan wasent bad but i guess it needed some lube i took some high temp grease and squirted it into the holes at teh fan assembly, immedily th noise wne taway.

 

crank case tensioner? maybe

 

could be your water pump bearing, how many miles do you have on the car and have you change the water pump berfore?

 

I got very close to 120k miles on it and I believe I had it changed when I first got it at about 113 or 115k miles. Timing belt, water pump was all replaced. My dad owns an auto mechanic shop but whenever I need something checked or done, the other customers are first priority so I haven't had it checked yet.