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Thread: Mystery noise when driving

  1. #1
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    Mystery noise when driving

    I have a 2013 CX-5 that was purchased new in April 2012. I replaced the tires once maybe two years ago. I also had the ECU replaced when the car started stalling a couple of years ago as well. I started noticing a noise after the ECU was replaced but I can*t say that the two things are connected. My wife drives the vehicle more than I do.

    The noise is a low frequency *thrumming* that increases in tempo slightly as the speed increases. It sounds like *dum-dum-dum-dum-dum...*. My first guess was that maybe one of the tires is out of round or is imbalanced somehow but the they have been rotated and balanced and the alignment has been done a couple of times since I started noticing it. The noise seems to be coming from the rear of the car, not the front. I even stuck my head out the window when my wife was driving to see if it was more noticeable from the outside, but I couldn*t hear anything besides the wind noise.

    The noise is there no matter which road I*m on (streets or highway) so it*s not a particular bumpy or poorly paved road that I*m hearing. It*s not there when I*m idling.

    I tried recording the noise on my phone. I apologize that the video is only showing my radio dials, but I just stuck my phone on the vent clip to record. You probably have to wear headphones or have a good audio set up to notice it. Around the 30 second mark is where you can hear it the best, but it*s very subtle.

    Here is the video

    I*m afraid if I take it in to the mechanic, he*s going to tell me that I need to do some major repair to fix it (shocks, bearings, who knows) or they*re going to charge me to look at it and not find anything and would like some ideas before going.
    Last edited by hooked; 10-10-2018 at 07:52 AM.

  2. #2
    Work in Progress sm1ke's Avatar
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    Do you have any mechanic friends, or have any friends who know a "shade-tree" mechanic? They would likely be able to look at it for a much cheaper price (if not free). A certified mechanic will always be better.

    Not all shops/mechanics are crooks. There are some great ones out there, you just have to find them. Check out the reviews on your local shops and take a visit to the best one to see what they're about. They might even be nice enough to hop in the car with you for a quick drive so you can point out the sound.

    This sound can be hard to figure out because it seems to be coming from under the car. Since it changes with speed/acceleration, it could be tied to the differential, transmission, CV joints or wheel bearings. To me, this sounds like it could be a bearing issue. If it were me, I'd tighten all lug nuts and go for a drive to see if that helped (it's just something I do, unrelated to the bearings). If not, I'd jack the car up and try pushing/pulling the wheel in and out from the top or bottom of the wheel. If there is any play, the bearing should be replaced. I had this exact same noise on a 99 Accord I had, and it turned out to be the wheel bearings.

  3. #3
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    Thanks. I*ll try what you suggest. I know it*s been a while, but how much would fixing the bearings cost?

    Edit: I do not know why quotes and double quotes are showing up as asterisks for me. I*m not trying to be fancy or anything.

  4. #4
    Work in Progress sm1ke's Avatar
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    Quote Originally Posted by hooked View Post
    Thanks. I*ll try what you suggest. I know it*s been a while, but how much would fixing the bearings cost?

    Edit: I do not know why quotes and double quotes are showing up as asterisks for me. I*m not trying to be fancy or anything.
    Don't worry about it, it seems to happen randomly and is a minor issue with the forum that mods are looking into.

    I don't know what a shop would charge for wheel bearings. I went to a family friend who happened to be a shade-tree mechanic at the time, he replaced the bearings on the driver's side in 1-1.5 hours I believe. He was happy with the bottle of Crown Royal I gave him as payment.
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  5. #5
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    So I jacked up both sides in the rear and there was no play in either wheel. However, I spun them and I could hear scraping/grinding noises from both sides and increased in tempo the faster I spun them. This seems to indicate, according to YouTube, an issue with the bearings.

  6. #6
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    Quote Originally Posted by hooked View Post
    So I jacked up both sides in the rear and there was no play in either wheel. However, I spun them and I could hear scraping/grinding noises from both sides and increased in tempo the faster I spun them. This seems to indicate, according to YouTube, an issue with the bearings.
    Are you sure that's not the sound of the brake pads on the rotors? Usually a wheel bearing noise is a whining noise that increases as the car goes faster, can notice it going around turns also.

  7. #7
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    ^^ Yep, could be something sticking in your brake system. Maybe even a small pebble that got stuck between the pad and rotor or something.
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  8. #8
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    Oh man! Just when I thought my diagnosis was complete. I should have gotten a recording of the noise. The noise I hear when I spin the wheels by hand (remember these are the rear wheels) is a low pitched humming(?) sound like wrrr...wrrr...wrrrr that increases in frequency as I spin it faster. There are some scratchy/scraping noises as well, but that humming is definitely there. However, it*s not a whining noise as described above. From the videos I watched, there should be hardly any noise coming when I spin the wheel if the bearings are good.

    I*ll try again tonight maybe. It*s a pain because I don*t have a floor jack and I have to use the pitiful tiny jack that came with the car.

    Other than the noise, what do I need to look for if it was some sort of brake pad/rotor contaminants? The rotors don*t seem to have any major gouges in them. Do I need to pop the pads to check?

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