I just purchased my new-to-me 04 black G35 Coupe 6MT with 32k miles last week, and i absolutely love it. Ive noticed though that after its been sitting out in the cold (below 32F) for awhile (at least 4.5 hours), i get a whine/hum between 35-45mph.

* It sounds like a wind leak through the window, but it's still there when i roll the window down.
* i can be in gear or in neutral, accelerating, coasting, or braking.
* i'm having a hard time telling where its coming from, other than the front of the car and i THINK the front driver side.
* once i've been driving for a few minutes it goes away, so obviously whatever it is must be at least a little temp-related.
* no vibration or irregular feeling accompanies the sound

i searched and found several threads of people saying they had the problem, but no one actually giving much input on what they're trying to fix it.

options people listed:

* Wheel Bearing: this i think might be likely, but i didn't find one person that both said they were replacing their bearings and that it actually fixed anything.
* Tire Feathering: this one is easy to check and i haven't been able to yet. however, tires get back to ambient temps in way less than 4 hours i'm pretty sure, so i'd think i'd have heard it after parking outside for like an hour, and i don't.
* Belt Slippage: it doesn't have the same whine as a belt slipping. i really don't think this is it (i actually think i might have a slightly over-tight belt too at startup, but it seems unrelated.)
* Internal transmission issue: one person said they fixed it by switching to a lighter tranny oil, but gave no indication of what oil they switched to. another 2 said they got transmissions replaced. i don't want it to come to this, as i'm still new enough that i've got no clue on warranty stuffs.

I'd be doing more experimenting myself, but its freezing outside, i don't have a garage, and i work 40+ hours and am planning a wedding

i'm hoping to get a thread here that will be people that have had the problem, and what, if anything they did to fix it. if that kind of thread already exists, please point me in the right direction, but i couldn't find it after a good deal of searching.

thanks in advance!
max

 

I would definitely take it to the dealer to start the process of documenting it in case it needs powertrain warranty work (powertrain warranty is good for 6 yrs/70k).

Have you checked the diff fluid? It's not supposed to need replacing yet, but who knows - yours could be low or dirty.

 

I haven't checked any fluids that aren't visible from the engine bay yet, cause it's too cold to get out the ramps and get under the car. I doubt its the diff simply because im 90% sure the sound is in front of the driver, but i suppose i'm no expert at sound dynamics while moving, so maybe i'm just wrong about that.

i think i'll be calling the nissan dealer on monday. I want them to run through the 30k mile list anyway, so we can kill 2 birds with one stone.

anyone else with experience on this? i know i saw a good deal of posts describing the symptoms, just not any with follow-ups.

 

This is most likely the transmission. I have the same problem and I have read about others as well. This could be a sign that you need a new transmission. Are you having trouble shifting into any gears or grinding at all? If so, i would suggest taking it to the dealer and explaining in detail what problems you're having. If they are not being cooperative with you, you could always check your regional/club forums and ask what dealership(s) they recommend. Here is a link to the midwestern forum. There may also be a forum for a club in the IL area, but the above link is a good place to start. Good luck!

 

mine does the same thing, and it happens to many Gs on the forum as well. there are a couple of threads on this issue but i couldn't find it. try do a search.

 

Many people have had this problem and I can't seem the find the post or thread that had pinpointed the source of the noise.

If I remember correctly, it's merely an air flap of some sort that opens and closes as the temperature heats up. I forget what exactly the flap is for, either for the engine temp, tranmission temp, the intake temp, or even the cabin temp.

When the flap is close, the air movement brushes up against it...making that howl or whine noise when moving at certain speeds and then goes away when the car heats up. Which is the majority of G35 only hear the first 10 minutes or so.

I'll continue to look for that post but so far, it's been a pain searching for it.

 

I did several searches over a couple of days. Like i said before, i found plenty of threads with people saying its happening, and nothing with anyone saying how to resolve the issue. hence this thread.

@bflemi: no drivability issues at all. if the whine is the transmission, is there a histoy of it eventually leading to bigger issues? is this something i could afford to take a little time and exhaust my options on, or could it lead to bigger issues if not addressed soon?

 

I remember reading that thread too. Somebody explained in detail what caused the whine. I never had that problem though until my transmission started to go. I believe that comes up as well. I'm scheduled to get a new one next wed.

 

I have the same issue but a more severe case. My car makes the roar/whine sound after it's been sitting anytime temps are below about 50-55 degrees. The noise is present from speeds about 15 mph to 45 mpg but goes away after 2-4 miles (warming up). The car has been extensively diagnosed about 6 times over the past 3 years at the dealer without success. The noise was first noticed after the car was about 1 year old. The last time the fixed operations manager test drove it with me and experienced the noise. We have ruled out:

tires (different set since noise started)
wheel bearing (noise would not only be in cold and go away when warm)

Do you have any mods such as plenum/throttle body spacer/ Z tube? I have all of these and the noise was noticed since installing them. Please keep us posted if you find the cause and the fix.

 

I relayed this "theory" to my dealer last year and they were not aware of any air flap that would cause this. It makes sense to me but I haven't read anything substantive on here that confirms this cause and any fix.

 

Lord Jeezus I found it. Thought I wasn't going to find it but yeah....it's a "cold air inlet damper"...read post #48 in thread.
https://g35driver.com/forums/engine-...en-cold-4.html


I've seen threads about this matter even long after this post was posted. Hopefully, the more we spread this info, the easier it is to find/search.

Keep in mind that the thread had three different noises being observed. So it's a little difficult to tell if everyone is talking about the same noise.

 

i'd be very interested in seeing theis flap thread as well.

wheel bearings only makes sense to me if the issue is that the grease in them is getting warm enough to lube the bad bearing after awhile. mostly i just wanted it to be that because it's a much easier fix than a new transmission.

bflemi: please let us know whether the new transmission addresses the noise.

rbull: have you talked about the option of a transmission with your dealer? if so, what has their response been?

car came with an injen intake, but no other mods that i'm aware of. I don't believe it's related though. A) i can hear the intake and its definitely not the same noise, and B) the noise is present when i'm not on the throttle at all. unless the intake has just shifted things in the engine bay and caused the howl, i don't think the intake itself is making the noise.

 

it sounds exactly like wind rushing, so that's a marvelous theory.

anyone know where this thing is on the car?

 

I can't really answer your first question as I don't have any factual evidence that it does. But that doesn't mean that it doesn't. I was reading over a previous post and remembered that the top of the transmission has a small breather hose (diameter is very small, maybe 2/4 cm). I suppose that air rushing out of the hose could cause a whistle/whine, but I haven't actually heard of that being the cause before and wouldn't think there would be enough air flow to cause a whistle that loud.

I would suggest googling transmission whine or something like that and see what you get. At least you could have some info you can bring to the dealer.

 

ok, so i'm poking around the Sewell site and i'm not seeing anything called the "cold air inlet damper" or anything called a damper other than the hydraulic damper for the clutch. I also couldn't find anything in the HVAC dropdown. starting to feel a "pics or it didn't happen" moment coming.

EDIT: downloading the service manual now, will spend some time poking around on that later. if it's a PDF i'll get it on my iPod so i can keep looking while im out of town this weekend.