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Deep resonating rumble in 2004 Prius

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Todd Kamens, Apr 26, 2019.

  1. Todd Kamens

    Todd Kamens Junior Member

    Joined:
    Apr 26, 2019
    3
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    Location:
    Arnold, MD
    Vehicle:
    2004 Prius
    Model:
    IV
    I have a low mileage 2004 Prius (120K) that is suddenly emitting a deep rumble when the engine is at the transition between starting and stopping by the hybrid system. The sound is most pronounced when the engine is at its lowest rpms and under load. It is similar to trying to accelerate a manual transmission car when the car is in a gear that is too high. Otherwise, it accelerates quietly and smoothly, brakes well, and battery charging system seems to be functioning normally. Any suggestions?
     
    #1 Todd Kamens, Apr 26, 2019
  2. JC91006

    JC91006 Senior Member

    Joined:
    Nov 10, 2013
    16,470
    8,384
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    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    Maybe someone has stolen your catalytic converter. Look under your car and see if something has been cut off
     
    #2 JC91006, Apr 26, 2019
  3. caravan2429

    caravan2429 Junior Member

    Joined:
    Sep 21, 2018
    64
    19
    0
    Location:
    Sandy, UT
    Vehicle:
    2007 Prius
    Model:
    II
    Rear muffler rusted or broken. Check your chassis first.
     
    #3 caravan2429, Apr 26, 2019
  4. Todd Kamens

    Todd Kamens Junior Member

    Joined:
    Apr 26, 2019
    3
    0
    0
    Location:
    Arnold, MD
    Vehicle:
    2004 Prius
    Model:
    IV
    I have already replaced the muffler and the upstream pipe that has a heat shield welded to it as that weld had let go. Rest of exhaust looks intact. Problem persists after the exhaust repair.
     
    #4 Todd Kamens, Apr 29, 2019
  5. JC91006

    JC91006 Senior Member

    Joined:
    Nov 10, 2013
    16,470
    8,384
    0
    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    The shop is probably not a professional shop, forgot the donut gaskets for the pipes.
     
    #5 JC91006, Apr 29, 2019
  6. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    54,835
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    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Noise commenced before the repair then?
     
    #6 Mendel Leisk, Apr 29, 2019
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