Noise when cruising in neutral

[sourapple]

I don't know if this is normal. I've seen a few vids but they all talked about different problems.

When I'm coasting in neutral or clutch in. I hear my s2k make a med/high pitched whine/hum. I cant really notice it when i am accelerating. But I'm curious, is it a differential going out? Or just a normal sound? Just tell me what I should be looking for, I could probably give more details than this.

[repiv]

I generally try to stay away from "noise" questions, especially when so little information is given. You say nothing about year of car, mileage, mods done to it, what speed the car is going or what rpm the engine is at. You don't say which end of the car it's coming from or if it's left, right or central. You don't say if it changes pitch or frequency as you slow down or it it's different when you are going faster. You don't say what kind of tires you are running or if you've checked the pressure. You should mention if the noise changes much when you lightly apply the main brakes or the ebrake. Can't really say if it's "normal" or not. This car makes a lot of normal noises. When it comes to "noises", the better question will generally result in a better answer.
Now, I hope you don't usually drive by coasting with the thing in neutral or with the clutch pushed down. This is not a good way to drive and I hope you are only doing it to hear the noise. That being the case, your noise should be confined to everything downstream of the tranny output shaft as these are the only things that turn with road speed and is independent of the engine. It could be any of the wheel bearings or the diff. Until you give more details, that's about all I would venture to guess or to suggest in terms of further diagnosis.

[sourapple]

2005 S2000

about 32K on the odometer
No Mods. just Stock.
Has new Falken Ziex tires

The sound starts off sorta high pitch, then whines down. When I am coasting, it starts to lower in volume and pitch as it slows down. I only started to notice it on deceleration. At first I thought it was just part of the buzz, so as an experiment i just coasted in neutral to see if it went away. The sound doesn't really change with brakes/ebrake. It more or less seems related to the speed I am traveling at. I only REALLY hear it when i have the top up.


Tire pressure checks out fine.

I have 2 questions mostly,

If it is a bearings - what should I do and look for?

If it is differential - Same question as above.

Hope this helps in details.

[repiv]

Another thing you need to comment on. Has this noise always been there as long as you've owned the car or is it something that has developed over time? If you've always had this noise, why are you concerned about it now? If it developed while you've owned the car, was there any landmark event about the car that you can think of where the noise began?
Can you rule out tire noise? I've never heard of the Ziex tire. Perhaps they are particularly loud. I don't know. Altering the tire pressure to excess just for a test will rule this out. The sound will change.

3 things that I can think of at the moment can be cause the noise you describe but given the miles and year of your car, I find these remote but not impossible. Was the car bought brand by you? Or did it have a previous owner?
1. Transmission output shaft bearing. Hard to test except perhaps that the sound will be more central to the car. You can also go under there and give the output flange a really good pull in all directions to see if there is excessive play. When was the last time the tranny fluid was changed? What's in there now?
2. Differential. Again, if there was a previous owner, could there be aftermarket gears in there? Does it make any odd noises when you do tight figure 8? Fluid? When done last? Sound would be centralized to the rear. Really bad gear whine in a normally quiet diff might show as a lot of excessive crud on the diff drain plug magnet.
3. Wheel bearing. Sound would be off to one corner. Bad wheel bearing noise can be aggravated by loading or unloading as when you take a moderate corner or curve while you hear the sound. Usually, a bad wheel bearing will heat up that hub more than the other corners.

[sourapple]

I am the 2nd owner of this vehicle, purchased from a dealer.

In terms of location, it seems to come from my rear center if not just under my right arm.
I will try loading/unloading on a curve.

The only other observation I have, is that the noise seems a bit more pronounced since it got much colder in the last week. Frost/Black Ice warnings in Southern California are quite the rarity.

Falken Ziex ZE-912 tires. They are considerably quiet compared to the Nitto's on my friend's 06 S2K.

I'm going to change my oil/Diff. Fluid this weekend. So I'll keep an eye out for any weird things coming out of my Diff.

[sourapple]

So i just noticed one new thing this morning pulling into work. When I pull into a parking space, turning left into the stall, i hear a clicking noise. Is that the bearings?

[repiv]

So i just noticed one new thing this morning pulling into work. When I pull into a parking space, turning left into the stall, i hear a clicking noise. Is that the bearings?

Pulling into a parking stall is a slow turn so you're not loading up the corner much, so wheel bearing is remote but still can't be eliminated yet. Could you tell which corner it was coming from? Or was it centralized to the rear? You can help a lot by trying to pinpoint the area the sound is coming from. We can't do that.
A clicking on a tight, slow turn is also an indication of diff problems. Have you ever changed the diff fluid? This should be done annually or every 10 to 15K. When you do it, it will be very useful to do a close scrutiny of the magnet and the fluid that comes out. It could be revealing.
Also check the torque on all your lugnuts and see that all your wheel weights are on firmly. We had a fellow years ago with a clicking noise. It turned out that one of his wheel weights were slapping around. The adhesive wasn't holding.

[sourapple]

So it turns out.... I just needed Differential fluid.... Everything is fine now....

[repiv]

So it turns out.... I just needed Differential fluid.... Everything is fine now....
Was it low or contaminated?

[sourapple]

It was blacker than the friday after thanksgiving.

[repiv]

You should change it again in the spring and then once a year after that. Fluid that black will leave enough residual to quickly contaminate the new fluid. One more change should take care of it.

[Miles69]

The diff fluid will be allways be that black, even after just 5K miles. Scared me the first time I changed it. Now I change mine every 10K ~ ish.
Did this also fix the clicking you heard when turning left?

[repiv]

The diff fluid will be allways be that black, even after just 5K miles. Scared me the first time I changed it. Now I change mine every 10K ~ ish.
Did this also fix the clicking you heard when turning left?
The first change is always the worst. In some cars, it'll be black after a few thousand miles. If you change it annually or every 10K, it shouldn't go that dark anymore.

[sourapple]

It did fix the clicking. I never hear it anymore.. even on the really cold days.