Hi everyone, I have a 2004 G35 sedan 6mt. While fixing my A/C compressor clutch, I noticed a weird whining noise the car makes if you rev it to at least 2500 rpm. After the repair I still hear the noise. It's possible the noise existed for a while and I just never really noticed. It's not really noticeable with the windows up but if you're idling with the windows down and rev the car up to 2500+ rpm you can clearly hear it.

When you take your foot of the gas and the revs drop below about 900rpm the noise goes away. If the A/C is on, the car will stay at about 900rpm for a while so the noise remains (noise still exists with A/C either on or off just remains longer with A/C on).

I have a video with the noise. Any ideas what it could be?

​​​​https://youtu.be/0vkjlfr6RO4

 

Sounds like a pulley making noise. Did you happen to spin the tensioner pulleys while you had the belt off to see if they were making any noise?

The tensioners should be completely silent and they should not be able to just free spin if you give them a whirl, they should make 1-2 rotations completely silent then come to a stop.

Also might have the belt a little too tight putting too much tension on a pulley.

Also check your power steering fluid, those pumps can whine pretty good if they're not full.

 

Thanks for the response cleric. Everything looked OK at the time I was putting it back together in terms of pulley play, some of the pulleys mainly the alternation and AC compressor I checked if it spins freely but not all of them. Power steering is at a good level. The noise is really not the noticeable and when I was walking on the sidewalk I heard a late model Nissan Pathfinder Hybrid drive by and it had the exact same noise. So I guess it's a Nissan thing. It's been three weeks since I finished repairs and the car and A/C is working just fine. I would probably not hear that noise unless I was listening carefully for strange noises (which I was when repairing the drive belts).