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Old 07-01-2013, 12:26 PM   #1
Dabrador
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Default Humming noise...what is it?

Need some help figuring out what might be causing a noise. Here are the details...

It started one winter day this past January. I was turning on a snow covered road at about 20 mph. The car slid sideways and the passenger wheels hit the curb. I got out to look at the wheels and they were scuffed from contact with the curb. The car still drove perfectly but after that, when the car is above 45 mph, I hear a slow, rhythmic humming noise. The noise is very subtle, but I can hear it.

I had the alignment checked...it was perfect. I took it to the dealer for the next oil change and told them about the noise. They couldn't hear anything (it is very subtle) so they didn't get into anything to check. I mentioned it again when I picked up the car and the tech said it was most likely the tires making the noise (I have 40,000 miles on the tires). He ran his hands over the tires and said they were starting to 'cup'. At highway speeds, he said that would cause the rhythmic humming noise.

Any thoughts? I just want to make sure that there's nothing serious going on. Thanks all.
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Old 07-01-2013, 12:47 PM   #2
sgoldste01
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My first guesses would be tires or bearings.
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Old 07-01-2013, 01:54 PM   #3
Dabrador
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Originally Posted by sgoldste01 View Post
My first guesses would be tires or bearings.
I asked the tech about bearings and he said (again, without looking) that if the bearings were going bad, the sound would be heard at low speed in addition to highway speed.
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Old 07-01-2013, 02:27 PM   #4
sgoldste01
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Quote:
Originally Posted by Dabrador View Post
I asked the tech about bearings and he said (again, without looking) that if the bearings were going bad, the sound would be heard at low speed in addition to highway speed.
OK, that's possible. So now I'm wondering:
  • Why are the tires cupped? Do you check your pressure regularly? Do you rotate your tires?
  • If the tires are cupped, why didn't they make this noise until after you hit the curb? If the alignment is good, the cupping should have already been there before hitting the curb, right?

Anyway, you have 40k on the tires, so they are getting old. It's not uncommon for tires to get noisier as they get older. So the tire theory is probably right.
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Old 07-01-2013, 02:45 PM   #5
Dabrador
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Quote:
Originally Posted by sgoldste01 View Post
OK, that's possible. So now I'm wondering:
  • Why are the tires cupped? Do you check your pressure regularly? Do you rotate your tires?
  • If the tires are cupped, why didn't they make this noise until after you hit the curb? If the alignment is good, the cupping should have already been there before hitting the curb, right?

Anyway, you have 40k on the tires, so they are getting old. It's not uncommon for tires to get noisier as they get older. So the tire theory is probably right.
Rotated tires every 7500-10000 miles. I don't regularly check the air pressure. It gets checked when the oil is changed (I know...need to get better at this).

You're second point is the one that's causing me to wonder. Is the curb incident coincidental with the humming noise or did it cause it?

There has not been an increase in the noise since January. It's the same subtle sound today as it was then. In addition, the car tracks perfectly on the highway.

If the tires are truly cupped and are causing the humming noise, would it also happen when the roads are wet?
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Old 07-01-2013, 03:02 PM   #6
sgoldste01
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Quote:
Originally Posted by Dabrador View Post
If the tires are truly cupped and are causing the humming noise, would it also happen when the roads are wet?
I don't know. It's possible that they ARE making the humming noise when the roads are wet, but the sound is so subtle that you simply can't hear it over the extra noise that wet roads create.

Does the noise come from the front, the rear, or both (or can't you tell)? If the noise is coming from one end (for example, the front of the car), then you can try rotating the tires and see if the noise moves (for example, from the front to the rear of the car).
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Old 07-01-2013, 03:17 PM   #7
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Quote:
Originally Posted by sgoldste01 View Post
try rotating the tires and see if the noise moves (for example, from the front to the rear of the car).
Already tried that and yes, the noise continued. I just crossed over 42000 miles so I'm hoping it is the tires since I'll be purchasing soon.
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Old 07-01-2013, 03:34 PM   #8
G2Spfld
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I'd bet its the tires. And you probably wouldn't hear it if the roads were very wet, as you would hear the water over the low subtle noise your describing. If roads were just damp and tires were hot you would prob hear it. That's kinda specific but I've found on here sometimes things get very specific. Only other thing I'd consider would be brakes, or slight rubbing if you maybe bent a rim slightly. I'm not sure how the hubs are on these cars as mine is too new, but I've seen issues like that ( when I did same thing with rear tires on my vette but on dry pavement) where a rim hits curb and slightly bends rim enough its closer to the brakes and just the noise from rubbing or the air between the two created a new resonance in the cockpit.
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Old 07-01-2013, 03:38 PM   #9
Dabrador
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Originally Posted by G2Spfld View Post
where a rim hits curb and slightly bends rim enough its closer to the brakes and just the noise from rubbing or the air between the two created a new resonance in the cockpit.
Hmmm...would a wheel alignment check uncover a slightly bent rim?
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Old 07-01-2013, 04:07 PM   #10
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Not necessarily. My alignment guy has a pad under tires and a tool that wedges inside rim lips. That piece is like 3-4 points of contact. I'm thinking his is only 3 points of contact. If the rim is bent slightly depending on where they happened to hang the device it wouldn't show. Now, if you watch it going down the road and you track your vision on the edge of the treads you should see a variation even if slight. I'm not saying that's your issue, its probably just tires, however I've seen it happen so its a possibility and worth a look. If its slightly tweaked it prob will not hurt anything except an uneven wear pattern on new tires over time. It wouldn't be a life and death thing that you need to replace before you drive it or anything.
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Old 07-01-2013, 04:15 PM   #11
Dabrador
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Thanks for the insight. I'm due for an oil change so I'll have them check the rims as a precaution.
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