Strange squeek-whistle noise.

I came back from work last night, got out of the car to check my mailbox and a strange squeeking-whistling noise came from the engine bay..I am pretty sure it is not the belt as the sound is different,maybe it is the water pump..what do you guys think?

p.s. It is not very cold down here,8 degrees (celsium) so it probably doesn't have to do with the temperature..


Tony
 
Last night i heard the same noise when i got back home.
I noticed that even if i slightly press the clutch the noise goes away...
Does that tell you something???