My alternator exploded yesterday, the back bearing went out and cracked the back case. So I go to Advance and figure I'll buy one of their brand new Palladium brand alternators with lifetime warranty, anyway it works fine but when the key in ON and the engine is NOT running I can hear a humming from the back of the alternator, and you can unhook the connector and it goes away. Never heard that from the old stock one. Just wondering if it's normal?

 

I got a high whine (not load but real whiny) when the key is in RUN but engine off.. Never had that sound with my old alternator, changed it out for a new alternator, the sound was there, called the store up, they sent me a new one, and that was same same a little noice when the engine is off..

Dont think you have to worry about it.. as long it charges as it should.

 

apparently not uncommon... mine does it, too. always wondered what the heck?

 

i would think thats weird but now you've got me wondering iv been working on my car for some time now every weekend and never noticed any noise but ill know tomorrow .

 

Ok, well I'll glad I'm not alone, maybe all of them do, but to hear it I almost have to put my ear to it, but my hearing is not the best, too many guns and loud concerts.

 

Nothing to worry about