Hey guys,

So i've got my 2010 g37x in the garage for a serpentine belt replacement. I also had a squeak noise at idle and figured one of the pulley bearings was shot. So, after removing the belt i found the tensioner pulley bearing, and 2 idler pulley bearings on their way out. Replaced with a new tensioner, and new bearings pressed into the idlers. Now, my squeak seemed to be coming form the alternator, as when i would rotate it, it would make a very slight squeak sound. Nothing bad, didnt sound like a bad bearing whine/hum, just a very faint squeak. So, i did the PITA job of removing the alternator yesterday and dropped it an a rebuild shop. They called me back, said everything was all good with new bearings installed.

When i got home i noticed it still squeaks, but only when i turn it ccw. Is this normal? Is there something else inside the alternator that could be causing the squeak? I might be giving the shop a callback tomorrow.

Thanks!

 

Here is a video link:

 

Did the shop rebuild the alternator or just replace the bearings?

It almost sounds to me like a bad slip ring or a unevenly worn (or dirty) contact patch on the rotor where the brushes sit (hard to explain).

I would clarify what the shop did and have them give it a 2nd go over. Now if they totally rebuilt the unit (new bearings, brushes, slip rings, the resistors/ rectifier/ regulator, and any other pieces, etc.) then a little noise would be considered normal and should fade away during the first few hundred miles (as the brushes and other components) break in. Ideally, when spun by hand, there shouldn't be any noise, but...

Again, find out exactly what work was done and see what they have to say about the noise.

 

Appreciate the response! From what he told me, he replaced the bearings and put it on his 'test machine' and it tested good. Thats all he did. I'm kind of wondering if he just put it on the machine and saw it tested good and gave it back.

The other odd thing i noticed is it only squeaks when spun counterclockwise, however, if im correct, its going to be spinning clockwise anyways. I hear what you mean by 'it shouldn't squeak'. It concerns me.

I've planned on taking it back in the morning and showing him the squeak to see what they say. I REALLY don't want to put it back in and find out i still got a squeak as i had a pain in the *** time getting it out as i got big hands. Thankfully moving the power steering pump out of the way made things a ton easier

Thanks!

 

It doesn't sound like a bad bearing to me. I'm willing to wager he just pressed in new bearings and called it a day. He should have at least cleaned the internals while it was apart- especially the rotor and the armature contacts- but...

Please update this thread when you have this resolved.

 

Will do!

 

Well, i took it back to the shop this morning. Shop guy said that its normal and nothing to worry about. I tried asking what it could be and if he was sure, and he just put it on his test machine to show me it didnt make any noise and sent me on my way.

I called another local alternator shop and asked my question of it squeaking only in the ccw direction. He said its normal, as the brushes wear in one direction, so when its turned in the opposite direction, they can make a slight squeak which sounds like what im hearing. He said as long as it wasnt causing any other issues or strange noises, im most likely fine.

Will provide an update once job is done!

 

That is inline with what I heard and thought as well. I'm sure you'll be good to go.
Thanks for the update.

 

Appreciate the response. Thanks

 

Maybe an opinion from the video however by trying to spin the alternator with the Pulley facing up you're placing a load that the alternator doesn't normally see.
The belt kind off keeps the armature in the proper place as it spins it. Spinning it on it's "butt" puts weight on the back bearing.

Try it sideways as like when it's installed. Lastly if the alt doesn't make noise in the direction it's supposed to go then you're good.
No way of knowing for sure until you install it.