Loud droning noise when accelerating

Discussion in 'Gen 2 Prius Technical Discussion' started by tylerjames, Dec 10, 2018.

  1. tylerjames

    tylerjames Junior Member

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    hello, louder than normal droning when accelerating. No issue with speed, and no lights come on in my 07 prius with 180k on it. Ideas? Was hoping to go on a 1000 mile road trip next week and this happened..
     
  2. bisco

    bisco cookie crumbler

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    bad exhaust system?
     
  3. PAUL SCHULTZ

    PAUL SCHULTZ Member

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    ditto on exhaust leak

    Paul
     
  4. Kevin_Denver

    Kevin_Denver Active Member

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    If it changes pitch with the engine speed (which can stay the same as the vehicle accelerates due to the CVT-like-drivetrain), I agree, it's mostly likely your exhaust, this is where I would look. Pretty easy to jack up the car and then examine the exhaust system using a flashlight to see if there are holes.

    If the droning changes speed with the vehicle speed but not the engine speed, most likely cause is wheel bearings.

    Less likely is a bad motor mount. I've had a car where you could hear and feel the vibrations of the engine on acceleration when the motor mount failed (metal-on-metal inside the motor mount). This you can tell because it happens more at the start of accelerating, and especially when accelerating rapidly from a stop due to more g forces on the engine. The sound goes away or diminishes a fair amount as the vehicle picks up speed.
     
    #4 Kevin_Denver, Dec 10, 2018
    Last edited: Dec 10, 2018
  5. Skibob

    Skibob Senior Member

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    How does your battery level look when this is happening?
     
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