I have a 2003 350z that I bought new. The car’s transmission exhibited the problems common in early 350z manuals: “Notchy” shifts and synchromesh failure (mine was failing in 5th gear). Nissan kindly replaced both the transmission (with the CD009 model) and clutch assembly under warranty at around 40k miles.

That solved the problems and all was good until about 2 years ago (at about 100k miles total miles on the car, and 60K on the new transmission and clutch assembly), when the transmission started to emit a low howl, but only when the air temperature was cold (below freezing), and only when in first or reverse gear. As soon as I got the car rolling (shifted into second gear) or the transmission warmed just slightly, the noise was gone.

I thought the noise must be the throw out bearing, so I replaced this and installed a new clutch assembly. The same noise remains.The noise must be coming from the transmission. The noise has no effect on operation; it just seems to be “cosmetic.” Has anyone seen or heard of this? Thanks. --Spike

 

Never happened to me on either my 350z or g35 (sold), but I would definitely check the remaining drivetrain...driveshaft joints, diff and axles, fluid levels.

 

I've got a cd09 with same howling when cold, goes away warm. I've heard of others having it, and haven't heard of it being linked to something failing, but I don't have any clue as to what it is other than the transmission.
The sound was present before my transmission fluid change and present afterwards, so I don't think it is related to improper fluid.

 

Gears will make noise to some degree, what fluid are you using?

 

I'm not sure. The dealership's invoice lists "Nissan Transmission Fluid."

 

I have done additional research on the transmission noise I describe in the first post on this thread. I searched this site, and also did a Google search of the web. Here is some common comments:

• The problem seems to be with the CD009 transmission.
• Most (but not all) owners mention that the noise occurs (or is worse) when the air temperature is cold, and that the noise goes away (or is significantly reduced) when the transmission warms.
• People report hearing the problem in a specific gear (sometimes one or two gears), and that gear varies from reverse and first, to second, third or fourth.
• Pushing in (disengaging) the clutch will eliminate the noise (and the reason I mistakenly thought this noise was the throw-out bearing).
• Just about everyone describes the noise as a whine or humming noise. There are multiple examples of this noise on YouTube that sound exactly like my car. In my case the volume depends upon the air temperature (i.e., the noise is louder in cold weather, and much louder in very cold weather).

People report attempts to eliminate the noise (mostly replacing the transmission fluid with something other than what they had), but there does not seem to be a solution. I think this just might be something I will have to live with unless I am willing to swap in a new transmission. I believe the latest model is the CD00A.

 

Now that you describe it more, my year or so old cd009 does whine or more like "whirr" (not transmission chatter) when in neutral an cold...something i hadnt heard on this platform before. And I have heard a lot of transmission chatter, and this is something different

I also noticed that with the car in the air, with the clutch pedal out (clutch engaged), the rear wheels spin slowly on their own, then as it heats up the wheels stop moving. If I clutch in (disengage the clutch) they stop. At any time if I touch the wheel it stops moving so there is very little torque being applied to the wheels...when it was newer it would do it more, but now as its had some miles it spins the rear wheels for less time before it warms up and stops.

But, no noise when in gear and moving, either cold or warmed up. Which is why initially I didnt mention the above.

 

^^ Yes. When my car is in neutral and the clutch pedal is out (not pressed down), I hear the noise. If I push the clutch pedal down, the noise goes away.
So... When there is a load on the transmission, I hear the noise.

 

I think its normal and a result of the improvements in the latest cd00a transmissions. Mine is actually a cd00a.

 

^^ I agree. I'm not going to worry about the noise. Transmission is functioning normally (other than the noise). Thanks for posting.

 

I would *SPECULATE* that it's just gear noise - as was mentioned in this thread's posts. The 009 successors, the JKxxx trans in my Z33N AND the EAxxx trans in my Z34N were the noisiest transmissions I've ever owned (gear rattle); but they functioned perfectly (other than the annoyingly soft clutch actuation.) Would guess this is a case of "If it ain't broke...."