hi all. was driving grand caravan 3.8 1997
all of the sudden started hearing a zzzzzz sound that followed the speed of my acceleration....open the hood and it sounds like it is coming from the alternator. by the way, after I first hear the sound my Battery light went on. when I shut enging the light goes off after I retart it but then it comes back on after driving a bit. Is my alternator no longer charging ?? Have you heard this noise before ??
thanks !

 

Maybe it's seizing up?


The way you describe it, sounds like it's bad and just draining the battery.


I usually start the vehicle and remove the Negative battery cable. If it dies, the alternator is more than likely no good.

 

Sounds like my '98 Neon and yes it was the alternator. In my cae she would start to sing if I had lights and AC (or any defrost mode) going, then the battery light would come on. Worked fine with no accessories on. I put a volt meter on the battery, got 12.0 VDC at rest, stated her up and got 14.1 VDC, then turned lights and AC on and she came up 12.9. I drove her for a few weeks in no AC, head light, or defrost mode and finally bit the bullet and put in a rebuilt alternator. So far (six months) so good.

 

Most likely bad diodes in the alternator. Get a digital volt meter and attach the leads to your battery. It should read between 13 and 14.5 volts as you goose the throttle. If it reads 12.7 or less, the alternator is dead and it's going to leave you stranded