2002 Buick LeSabre Chirping Noise

Has anyone experienced a fairly loud chirping noise problem on a 2002 LeSabre? the noise is intermittent - stops when brakes are applied - or when I activate the recirculate button on the AC - the AC or heat must be on. I can pinpoint the noise as "in the vicinity" of the alternator. Only occurs after highway travel exceeding 50-70 miles and can last for about five minutes before it stops. Noise changes pitch somewhat as engine revs increase or decrease. Not the rotors or pads as the noise continues when stopped and engine idling. So far two Buick dealers are clueless. The alternator and serpentine belt have been replaced with no effect. ___________________________________________________________

We had a similar elusive chirp condition in our 92 Buick 350TBI. Suspected the alternator because electric loads affected chirp; suspected the AC compressor clutch pulley; suspected and replaced idler pulley and belt. No one could find the cause, which continued for about 400 miles before the problem showed itself: Sparks started flying from the water pump bearing, followed by a spray of bearing rollers.

New water pump: Blessed silence.

Wendy & John. ___________________________________________________________