Weird noise coming from under the hood

So last night I hop in my car to drive home and I start driving and I start hearing this weird sort of like high pitched whining noise coming from the engine. So I keep driving home and it keeps continuing. I park it at home and go to drive it today and its still doing it. It does it at idle but then if i tap the gas a little it goes away until it falls back to idle. When driving it will do it at a constant rpm.


I stuck my head under the hood and I cant tell from where its coming from either. I just did a 3g install and it worked great no problems or nothing but I cant tell if its coming from the alt or the water pump area.

Alright thanks, also when I did my 3g install I reused my stock belt. Is that okay with the tensioner? The belt is pretty tight my old alt got a bad bearing and someone said it was because my belt was too tight. Is that true, could that becausing the noise.


Oh yeah last night I took her for a spin and the noise was gone. I dont know how or why.

Its not the throw out bearing. I just replaced mine with the steel one. Made a similar noise just from the motor and the noise varies threw out the rpm range. But aft 3k it stops.