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Loud strange noise while driving in a straight line

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by djimbuser, Mar 15, 2021.

  1. djimbuser

    djimbuser Junior Member

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    So the previous time I drove the car this noise was absent.

    It seems the frequency of the noise is faster than a revolution of a wheel.

    When I turn a circle and drive the noise disappears.

    On a downhill the noise is the same driving vs coasting in neutral.

    It sounds like a single-prop airplane flying overhead.

    I inspected both front wheels/tires and the tires are free of foreign matter, inflated to 40psi.

    Please listen to this and let me know your thoughts? Post info | SndUp
     
    #1 djimbuser, Mar 15, 2021
  2. mr_guy_mann

    mr_guy_mann Senior Member

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    That noise is a bad wheel bearing (sounds something like a "growl"). Turning the car changes the loading on the bearing, so the balls don't ride on the worn spot of the bearing race. Finding which one is bad can be... interesting.
     
    #2 mr_guy_mann, Mar 16, 2021
  3. edthefox5

    edthefox5 Senior Member

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    Finding which side is bad is easy.

    if you turn left hard and the noise is worse
    It’s the right wheel bearing. If you turn hard right and noise is worse it’s the left bearing.

    My drivers side failed at 33000 miles and was fixed for free by dealer 3/36.

    Doing that test it was clearly obvious which side was bad.

    It’s speed dependent at first so find the speed it does not like and do the turn test.
     
    #3 edthefox5, Mar 16, 2021
  4. ChapmanF

    ChapmanF Senior Member

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    Yes ... yes, it can.

    I've seen where all of the "easy" tests that are supposed to make it "clearly obvious" were either completely inconclusive, or would have indicated the wrong bearing, and the only thing that really worked well was a four channel wireless stethoscope to listen directly at the bearings while the car is driven down the road.

    The good news was, that stethoscope made a positive ID of the failing bearing in about three seconds flat.
     
    #4 ChapmanF, Mar 16, 2021
  5. djimbuser

    djimbuser Junior Member

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    I have no problem changing them both from the get-go, lol. I prefer them being at the same wear level anyway. The load makes sense. When I raise the wheel and spin it in neutral as fast as I can it doesn't make the noise. I'd be so pleased if it's something as simple as wheel bearings. I'll check back once I replace the bearings. I also drained out the tranny fluid and putting fresh fluid in today.
     
    #5 djimbuser, Mar 17, 2021
  6. mr_guy_mann

    mr_guy_mann Senior Member

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    Given that it can be fairly difficult to replace the bearing assemblies due to corrosion build up in the aluminum steering knuckles, you might want to confirm that the noise is in fact coming from the front.

    Usually a bad front bearing will still make noise if the car is (safely) raised and supported, then driven with traction control disabled to 40 or 50 mph. If it makes noise then it will also cause the coil spring on that corner to vibrate a lot in comparison to the other side, but you must be extremely careful doing anything around moving parts on the car.

    A "chassis ear" remote microphone system is good for tracking down the source.

    Posted via the PriusChat mobile app.
     
    #6 mr_guy_mann, Mar 17, 2021
  7. djimbuser

    djimbuser Junior Member

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    The noise is LOUD and it's definitely coming from the front. I'd say almost certainly from passenger's side. The noise was so loud my wife could hear it from inside the house as I drove past at 25mph.
     
    #7 djimbuser, Mar 17, 2021
  8. djimbuser

    djimbuser Junior Member

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    A follow-up as I said I would do. I bought one bearing from AutoZone and replaced only the passenger side which was my belief of where the noise was coming from. It's now fixed! Thank you everyone that responded for sending me down the right path.
     
    #8 djimbuser, Mar 22, 2021
    Steph1972 likes this.
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