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RATTLING SOUND IN THE DRIVETRAIN

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Former Member 68813, Oct 31, 2015.

  1. Former Member 68813

    Former Member 68813 Senior Member

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    I have 70,000 miles and this weird rattling somewhere in front, probably drivetrain, only audible at 60-70 mph, medium load, so no pinging. worse on high speed right turns, like highway entrance, and in this circumstance audible at about 50mph.
    i recently did cleaning of intake manifold, EGR pipe, and TB and an oil change and no change.
    the noise is totally absent in city/suburb style of driving with speeds up to 50mph.
    what could that be?
    it's clearly getting worse. could it be connected to the CV clicking noise i have at slow speeds?

    update: i searched some more and there are few threads about noise that sounds like pinging, but doesn't behave like pinging. no resolution except for the standard advice about higher octanes and gas additives:

    Engine ping under load | PriusChat

    Higher octane gas for fuel pinging | PriusChat

    engine pinging: anyone else have this | PriusChat
     
    #1 Former Member 68813, Oct 31, 2015
    Last edited: Nov 1, 2015
  2. bisco

    bisco cookie crumbler

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    exhaust heat shield?
     
    #2 bisco, Nov 1, 2015
  3. Former Member 68813

    Former Member 68813 Senior Member

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    i don't think so, the sound is from front and most likely engine compartment.
    BTW, thanks for replying.
     
    #3 Former Member 68813, Nov 2, 2015
  4. Former Member 68813

    Former Member 68813 Senior Member

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    update. it's getting worse. sometimes (rarely though) i can hear it while driving in city at 35-45 mph. no impact of AC, or engine load, turning, or road irregularities. just comes and goes. sounds like transaxle to me but not sure. i will change the ATF in a few months to see if it helps. i previously changed ATF at 22,000 miles, so it's under 60,000 miles on the fluid.
     
    #4 Former Member 68813, Jun 11, 2016
  5. bisco

    bisco cookie crumbler

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    that would be highly unusual, but as they say, things happen.
     
    #5 bisco, Jun 11, 2016
  6. Robert Holt

    Robert Holt Senior Member

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    I have heard of old school mechanics putting a small microphone mounted temporarily under the hood at different places and then listening to it as they re-create the conditions for the suspicious sound. Done carefully, that procedure may allow you to home in on the faulty part. The poor man's alternative is to ride with all windows down and long-suffering DW in the passenger seat, and then carefully listen for the rattle sound bouncing out from underneath the car.
    BTW, if you are getting any kind of vibration or jiggling in the steering wheel that occurs with the sound, I would suspect then drivetrain and more specifically the constant velocity joints between the tranny and one wheel. But if absolutely smooth when the rattle occurs, then I would suspect a resonance problem where some part such as the heat shield around the catalytic converter, is gradually working itself just loose enough to resonate when the correct frequency and strength of input pulses is hitting it.
     
    #6 Robert Holt, Jun 11, 2016
    bisco likes this.
  7. RyanFlorida

    RyanFlorida Member

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    I have heard similar problems on some of my other cars and even my motorcycle. From I can figure, it is the tires! Are your tire treads getting worn properly? It sounds like you do your own maintenance, do you rotate your wheels properly? And with 70K miles you should be on your second set or tires possibly nearing the third set.

    From experience on my motorcycle, I can hear a humming noise, especially in turns and at certain speeds it gets louder. I have yet to replace my tires on my motorcycle, but I am confident that's what it is.
     
    #7 RyanFlorida, Jun 13, 2016
  8. bisco

    bisco cookie crumbler

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    i'm getting this at 40,000 miles on the oems. tread looks okay, i wonder if cross rotation would help? might need balancing too.
     
    #8 bisco, Jun 13, 2016
  9. Former Member 68813

    Former Member 68813 Senior Member

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    mine is quick rattling (sounds more like hard drive crunching noise) and not humming. i have that humming from the tires alright, but that's different.

    are you talking rattling or humming?
     
    #9 Former Member 68813, Jun 13, 2016
  10. bisco

    bisco cookie crumbler

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    definitely more of a hum/drone. and it feels like there's a flat spot on one of them. a little vibration. depends on the type of asphalt as well.
     
    #10 bisco, Jun 13, 2016
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