# Strange Noise Coming from Differential



## stratonick (Dec 4, 2007)

Just picked up a 2004 Certified Preowned 350Z (Manual 6 Speed) from Flemmington Nissan with 41K miles on it.

Everything seems fine except from the moment I start driving it in the morning until it fully warms up (approx 10-15 Minutes) I hear this strange "Whirring Noise" from what I can only assume is the rear differential... as soon as the car is FULLY warmed up this noise ceases.
Also, this sound will only occur when the car is moving....if I rev the engine a bit in neutral I dont hear anything unusual.
Any ideas? I know that the Enthusiast Edition (which is what i have) has a "viscous limited slip" read diff. (whatever that means....basically posi-traction i guess) but has anyone else ever had this issue?


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## rbo1577186 (Jan 16, 2005)

How are you sure it's the diff?


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## stratonick (Dec 4, 2007)

I'm not sure of anything..... but I'm hoping that someone else here may be able to give a point in the right direction. 
Also, there are no other issues that i can find, the car brakes fine, wheels are ok, exhaust is tight, the sound I'm hearing is definitely coming from somewhere in the back / underside of the car. 
This only happens in the morning, as soon as it warms up its gone. The brakes dont really warm up unless used quite a bit, and the sound doesnt change if i use them or not, and the exhaust pipes get hot within 3-5 minutes or so, and i hear this "whirriing" long after that.

Dont really know what else it could be.....


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## rbo1577186 (Jan 16, 2005)

You need to put it up on a lift or jack stands or something and pinpoint noise. You can remove the driveshaft to diagnose the diff or brakes. If it still persists, its in the tranny somewhere. You can use a long screwdriver as a make shift stethoscope to find the noise. Put the blade end on the diff or tranny (if on a lift) and the handle at your ear. Where the "whirring" noise is loudest, and you will find where your problem lies. 

Check your fluids also to eliminate that possibility. This is a vague description, so I don't know any other way to track it down.


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## stratonick (Dec 4, 2007)

UPDATE - Just got my car back from the dealership last night.....

Ok so i picked my car up from the dealership today after it was there for a little over a week.
They said that they wernt able to pinpoint where the whining sound was coming from but they replaced the "pilot bushing" and the "throw-out" bearing thinking that was the issue. Now i have my car back, the whineing sound SEEMS to be gone. But now the clutch is "rough" either starting out in 1st gear or reverse. It was VERY smooth to engage the clutch in ANY gear BEFORE i dropped my car off to the dealership.
It almost feels like the clutch is "shaking" when i let the pedal out into 1st or reverse gear. No matter how little / how much throttle i give it (usually dont need much to get into 1st gear). If i rev the engine up to about 1500Rpm then there's no rough/shaking when starting out in 1st, but my guess is that either the tech. who drove it had NO idea how to drive a standard shift car, or maybe there's some kind of clutch adjustment that didnt get done after the new throwout bearing was installed?
Either way i called the dealership on the way home and let them know that after christmas i'm going to be making a return visit so this can be fixed, but I'm wondering if anyone else has any knowledge on this, I dont want to walk back into the dealership without some info to tell them.


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## sport (Jan 16, 2011)

What was the resolution of this posting? It sounds like I have the exact same thing going on with my '06 350Z Touring model. I would describe the sound almost like a loose or failing bearing, a variable vibration noise. It only really becomes noticeable above 40 mph and really kicks in above 50. It is modulated slightly by throttle input when the transmission is engaged but is generally independent of transmission position. That is, when at highway speed, the noise is manifest regardless of transmission position (any gear or neutral, clutch in or out). It is definitely a cold condition phenomenon as indicated in the original post.


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## stratonick (Dec 4, 2007)

The resolution is basically...........nothing. Still have my Z, and i STILL get that same noise (though not as often as i used to) on cold days, where my Z hasn't fully warmed up. Typically before i head into/out of work, etc - car needs to be sitting out in the cold for some hours, before it happens.
Never had any issue in all this time that came from "the noise", but something that I DO KNOW is: that this whirring/vibration sound that some of us Z owners have noticed on cold days....that sound can be heard from outside the car as well, and it's much louder than you think. 
Actually it's embarrassing.......sweet car like the 350Z, wheeeeeezing past people on the street, especially on the morning drive into work.....ugh.

Never could get a straight answer on it, and i made several attempts over the years I've had this car to figure it out...Nothing from 3 separate dealerships....and sadly, nothing back from anyone here on this forum.

If you make any headway on this issue though, PLEASE let me(us) know!!!


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## sport (Jan 16, 2011)

OK. If I get anywhere with it, I'll be sure to post. In the meantime, I guess the good news is that you've been able to continue driving it all this time without incident, just the annoying noise, so apparently it doesn't indicate an impending failure of some kind.


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## sport (Jan 16, 2011)

I did find another post at
Transmission & Differential Oil Change! - Nissan 350Z Motoring Forums
by an owner who said he used Red Line diff oil which seemed to cure a noise he thought was coming from the rear, but I have not yet tried this solution.


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## sport (Jan 16, 2011)

*It's somewhere in the transmission, not the diff*

I took my Z to the Sheehy Nissan dealer in Waldorf, MD. They traced the noise to the transmission, not the differential, similar to one of the experiences you described. Since I had purchased the extended warranty, they simply replaced the transmission, which has worked quite nicely for me. I asked the service rep what exactly was the problem, but he said they no longer tear down items for such warranty work; they just pull the major component and send it to Nissan, who does the failure analysis. I'm afraid this might not help much if you're not prepared to buy a replacement transmission, but at least you have confirmation that it's a transmission problem. It is strange though that I too thought it was coming from the rear. Did you ever try the Redline fluids I mentioned from the other forum? I don't know if the fluid has ever been changed in your transmission, but you might also try putting a fresh batch of the Nissan spec oil in it. You can get it in quarts from Nissan, though it might need to be ordered. The part number is 999MP-MTF00P (those are zeroes, not O's).


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## stratonick (Dec 4, 2007)

@sport-Thank you for the followup info! That is a LOT farther then i ever got, when dealing with any of my local Nissan Dealerships.
Unfortunately for me, my manuf. warrantee just expired this January, so if i want any resolution on this issue now, I think that i'll go the "transmission fluid" route, as you suggested.

Nissan dealership keeps dangling their "Pre-Owned Security Plus" (4Yrs/48,000 miles) extended-ed warrantee package at me, now that I'm at 71K mileage on my Z, and out of standard warrantee.
It would cost me $2000 to purchase the coverage, and though it seems to cover all major components, it doesn't cover as much as the original Nissan Warrantee did.

Any thoughts from you fellow Z drivers on this? Is it worth it?

Thanks!


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## Shadao (Aug 14, 2007)

becareful with using that redline tranny fluid.... i know with my gtr32 if i use the redline heavy shockproof tranny fluid it will make shifts ALOT smoother but it will corrode and disolve the copper syncros...

the sound you guys are talking about makes me think " throw out bearing " my gtr32 has a twinplate clutch but the throwout bearing wasnt done when the clutch was, when the car is in gear or in nuetral you can hear a rattling but tends to go away when underpower and when warmed up... so perhaps look there


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## stratonick (Dec 4, 2007)

@Shado - Thanks for the heads-up, def. something to consider! Sorry to say that the throwout bearing is where i went looking as well, (one of my 5 visits to Nissan dlrshp) I even made such an issue out of it in the middle of the "customer service room" full of customers, that they agreed to replace my throwout bearing under warentee, even though it was in good shape........

3 days later on my way to work, this "noise" returned....same sound, same amount of noise--dammit!!!

So would ANYONE here be able to give me some advice on my previous post regarding "Pre-Owned Security Plus" extended warrante? Really dont want my Z staying in an unwarrantee'd-state for too long - Also dont like having to pay $300 for little things to be fixed, if they break!


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## rogoman (Dec 16, 2004)

stratonick said:


> Everything seems fine except from the moment I start driving it in the morning until it fully warms up (approx 10-15 Minutes) I hear this strange "Whirring Noise" from what I can only assume is the rear differential... as soon as the car is FULLY warmed up this noise ceases.
> Also, this sound will only occur when the car is moving....if I rev the engine a bit in neutral I dont hear anything unusual.


You might want to put the car on a lift; the type that has four adjustable arms so that the car's rear wheels are free to turn. Now start the car, put it in gear and listen to where the noise is coming from. It's easier this way since you can walk under the car and preciously pin-point the location of the noise.


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