alternator rattle noise

[BlackDynamite]

Well, lately I've noticed an un-synchronized(random) tapping noise from under the hood at start up. SO i investigate. I thought it might be the top end, but i did more investigating and the noise is coming from the alternator. I haven't noticed any voltage spikes or drops indicating that the alternator might go out but...what might that noise be? is it good or bad?

Looks to be a local auto parts store re-manufactured alternator.

 

[Nick M]

Well, there are bearings inside. On each end of the rotor. I can't say I have heard them rattle, then stop.

Sounds more like tappets low on oil to me. And we don't have those kind of tappets.

 

[cuel]

I've gotten rebuilt alternators with the big nut that holds the pulley on loose. Might check it.

 

[BlackDynamite]

well i noticed that my belt was a little loose....didn't have the tools with me. how tight is the belt supposed to be? I've heard of over tightening belts can mess something up.

 

[CyFi6]

over tightening the belts will just put that much more strain on the accessory bearings, so that is not a good thing.

 

[BlackDynamite]

well i tightened the belt up and it stopped the noise...the bolt on the alt pulley was not loose. Hrmmm...well i guess I'll keep checking it just make sure it is ok :]