Thread: Whinny noise from Alternator side??

1998 GTP 4-door

Well, I am at it again with changing noisy idlers and pulley. I noticed a high pitch noise, which seems to be coming from the alternator or perhaps the tensioner pulley right below it. My lights are not dimming or any indication of an alternator failure. I would hate to change a good alternator. I have recently changed the idler and belt tensioner pulleys used on the S/C belt. The loud squeals went away as the noise definitely came from the S/C belt operation. Any thoughts about changing the alternator ($250.00 GM OEM). The belt tensioner pulley on the alternator belt is only $35.00 GM OEM. The noise just started. I must also add that I had washed the engine and many times before that and never had squealing problem. Took it on a long drive hoping any moisture trapped would have disappeared after reaching highway speeds. Still the same squeals from the top where the alternator is located.

could be both actually. what i thought was my altenator. it was the belt tensioner.

Originally Posted by boosting98

could be both actually. what i thought was my altenator. it was the belt tensioner.

Thanks for the response. Perhaps, I should replace the pulley on the alternator belt tensioner and see if this noise goes away...the two pulleys are so close together...I would hate to spend $250.00 on the alternator

^that alternator belt tensior is most likely your problem. should make like a hissing sound.

I will definitely give it a world...the sound is not so much grinding but "pitchy" --high and low squeals.

Originally Posted by Burgundyman

I will definitely give it a world...the sound is not so much grinding but "pitchy" --high and low squeals.

UPDATE....When I removed the tension pulley I noticed a bit of play and a rattling noise when rotating by hand. I replaced the tension pulley (GM 24506756, $38.16).Noise is gone. I have not taken it on a test drive yet but I suspect that this should remedy the problem. I checked the alternator pulley for any play, while the belt was off and did not notice anything unusual. There was a slight squeak but is disappeared when I rotated it quickly by hand.

very nice. u should notice the supercharger whine alittle more than usual 2!

If it doesn't fix it you might try power steering...I know it isn't on top but it is worth a shot at least checking to see if that is where it might be coming from

Originally Posted by bluegtp91

If it doesn't fix it you might try power steering...I know it isn't on top but it is worth a shot at least checking to see if that is where it might be coming from

I did check the power steering pump pulley and also the fluid level. Everything seemed fine. The new pulley from GM is metal and much more sturdy than the plastic housing pulley that I removed today. GM must have figured it was flawed and improved on the design.

Final Report...Problem cured.

Originally Posted by Burgundyman

Final Report...Problem cured.

ok....noise is back with a vengeance...It is definitely the alternator...It appears to be the rear bearings...I am going to replace it with an OEM from a buddy who works at GM.