Hi,
I'm new to forum, my gf has had her g35 for a while, it has served her well and has been basically problem free. Within the last couple months it has developed this noise that has perplexed us as to what it may be. We replaced the belts and idler pulleys(this is what the dealer recommended it needing to fix the noise) but the noise is still there. Are any of you familiar with a noise like this on your cars, and what it may be? The car has 154,000 miles Thank you

 

I had this noise too.

I changed the motor oil and for some odd reason it went away and never came back.

 

Noises are a bitch to pinpoint....like this one! It's in rotation with the belt and sounds like a worn bearing. Try the "Screw Driver" method on every area from the air conditioner to power steering. (be careful) You do have clean oil, and it is up to the full line?
Gary