Engine rumbling on start up and while driving

Discussion in 'Gen 3 Prius Main Forum' started by Cherry Killingsworth, Sep 24, 2025 at 7:41 AM.

  1. Cherry Killingsworth

    Cherry Killingsworth Junior Member

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    I have a 2010 Gen 3 Prius with 269,483 miles (as of posting). It started a few months ago. We changed the spark plugs last Saturday (an ordeal for another time) and it seems like it got worse. It's also had a recent oil change. We have noticed that the antifreeze is starting to run low after just a few days. We keep refilling it. We are at our wits end because we can't afford another car and we love this car. I tried to attach a video of the engine noise, but the file is too large.
     
    #1 Cherry Killingsworth, Sep 24, 2025 at 7:41 AM
  2. ASRDogman

    ASRDogman Senior Member

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    The head gasket has failed..... That's why you are loosing coolant.
    That's why it knocks on cold starts. It has likely failed between #1 and #2 cylinders.

    If you fix it now, you might only need to have the head gasket, and hope the head is not warped.
    If you wait, and continue driving it like it is, you risk bending a rod, or having it go through the block.

    If you are able to replace it yourself, it will cost you a lot less money. Labor is a lot.
     
    #2 ASRDogman, Sep 24, 2025 at 7:57 AM
    PriusCamper and Brian1954 like this.
  3. Tombukt2

    Tombukt2 Senior Member

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    Another car and soon another engine in the car you love . Quite costly for 300K mile car.
     
    #3 Tombukt2, Sep 24, 2025 at 8:26 AM
  4. Tombukt2

    Tombukt2 Senior Member

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    Tough love
     
    #4 Tombukt2, Sep 24, 2025 at 8:26 AM
  5. Grit

    Grit Senior Member

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    Good run. Replace head gasket and do the illegal commieformia oil catch can install or replace vehicle.
     
    #5 Grit, Sep 24, 2025 at 10:54 PM
  6. Mendel Leisk

    Mendel Leisk MMX GEN III

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    #6 Mendel Leisk, Sep 25, 2025 at 9:01 AM
  7. Mendel Leisk

    Mendel Leisk MMX GEN III

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    Since new, recently acquired? That’s a LOT of miles for a gen 3. Head gaskets, on ones without regular EGR cleaning, usually fail around 150~200k miles.
     
    #7 Mendel Leisk, Sep 25, 2025 at 9:05 AM
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