93 1500 4.3 L Screeching

:banghead: My truck motor has this terrible screeching sound. Its not internal and its not from the belt, The belt is new and is not loose, Sounds like its coming from the tention pulley, can somebody give me any ideas? when idling it chirps a little but when you rev it up it screeches badly, I mean it will not stop. Please Help Me!!!!!

IS it only the first like minute after startup? or is it constant? My 87 F-150 schreeches really loud after start up because the altonator has a big load on it. Wierd..i kno

Welcome to AF. I'd take the belt off and look for a tight pulley, a/c bearing or any other rotating component. BTW in the future post your questions in the appropriate truck forum below.