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Strange road humming sound

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by hmd, May 14, 2019.

  1. hmd

    hmd Junior Member

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    Driving in city around 30-35mph, I've been hearing a weird humming sound--seems like it's coming from the right front. It's the sound your tires make when you drive over smooth and then uneven asphalt or concrete. It's a new hum, which occurs randomly. At first I thought it might be bearings, but it occurs only when I'm driving straight on. Car has new all-seasons, which I just had remounted. So the tires themselves are properly inflated. Thoughts? Suggestions? Thanks.

    (Car has 225K miles.)
     
    #1 hmd, May 14, 2019
  2. bisco

    bisco cookie crumbler

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    could also be the constant velocity joint. or maybe you got a bad tire.

    first try rotating the tires to see if the sound changes. if not, put her up and see if the is any play in the wheels.

    check the cv boots for cracking or leaking.
     
    #2 bisco, May 14, 2019
  3. hmd

    hmd Junior Member

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    Thanks. I'll have it checked. Any chance it could be wheel bearings?
     
    #3 hmd, May 14, 2019
  4. bisco

    bisco cookie crumbler

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    yes, that's why you check free play. sometimes they have to get really bad before you can identify them. a good mech should be able to from experience.
     
    #4 bisco, May 14, 2019
  5. ChapmanF

    ChapmanF Senior Member

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    Here's a thread (and its continuation thread) on some ways of judging what hums might be what.

    Caveat: it was for a Gen 1, so the Gen 2 bearing specs (and resulting pitches) might be different.

    If the pitch of the hum changes with road speed, and you have a way of matching what it is at, say, 30, 40, and 45 miles an hour (at those speeds, it should be the first, fourth, and fifth notes of some diatonic scale—Western music's favorite progression) it might give you some evidence. My Gen 1 front bearing made g, c, and d at those speeds, while the rear made e, a, and b. A little bit flat, but close enough.

    Also, the ChassisEar turned out to be a really effective tool for pinning down just what was making the noise.
     
    #5 ChapmanF, May 14, 2019
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