This is a long shot I know but want to see if anyone has suggestions regardless.

Been hunting down a rattle for awhile and finally sourced it to the alternator. The rattle only happens around 1000rpm and is far more audible when the car is cold. It more or less goes away after long drives. The alternator is suspect because it shakes pretty violently every time the car revs through 1000rpm and when we held the alt with a stick to prevent it from shaking so much the rattle went away.

Is it normal for the alternator to shake around like that? Do alternators sometimes begin to rattle if they are failing?

Right now I think it's one of 3 things
1) something inside the alternator is rattling
2) the alternator mounting bolts are loose
3) the alternator pulley is loose

Any thoughts?

Specs: 2006 with 80k miles, belts are 2 years old, battery replaced 1 year ago, original alternator and it works fine besides the rattle... battery is always charged and voltage is normally at ~14 while driving.

I'm going to take it all apart and see what's going on but trying to decide if I want to drop 400 coins on a new alternator. My "garage" is 400 miles away so planning ahead is necessary.

 

something isnt right. check slidgegood.com

http://www.slidegood.com/nissan/350z?part_type=221

 

Tighten the bolts it shouldn't be moving or shaking... My guess. They are bolted to the engine it shouldn't be moving anything but the pully.

 

Check this out.

 

you're welcome for that gif btw.

but yeah, check the 2 bolts holding it on first, make sure they didnt come loose

 

Can you move it by hand? Ive seen mounting bracket brake and tabs brake... It cant be moving much if your belt stays on and its odd that it goes away after its warmed up.

 

Update: Checked the top mounting bolt of the alternator this afternoon just by reaching down in the engine bay. Was able to tighten it two full turns with a ratchet and now the rattle is gone.

Can't believe it was so simple. I have been living with that rattle for years thinking it was the timing chain or some part of the exhaust.

 

sometimes it is easy to overlook the simple

 

Nice glad it was easy peasy.

 

Okay so the rattle is gone but I don't think the underlying issue is resolved. The vibration at 1000rpm when cold is still there despite the rattle being gone. I'm guessing the vibration is what caused the alternator mounting bolt to come loose in the first place.

So I'm trying to figure out what the culprit could be which leads me to this question. What is attached to the other side of the alternator bracket (number 6 in image)? It looks like it might be the power steering pump according to this image.

Can anyone confirm that?
Is it possible that my power steering pump is dying?

I noticed this morning that turning the steering wheel slightly while stopped will trigger the vibration non stop... it did however conveniently drop the rpms to exactly 1000 while I was doing it so it could have been coincidental.

Power steering fluid has never been changed

Thoughts?

 

Rattle is back... Probably need to torque down that bolt but seems like the root of the problem is not resolved

 

Is it stripped out and keep loosening? Maybe throw some locktite on that bad boy if its loose again.