2011 radiator pressure.

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by bob11x, May 19, 2025 at 10:42 PM.

  1. bob11x

    bob11x Junior Member

    Joined:
    Apr 28, 2011
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    Location:
    upstate ny
    Vehicle:
    2011 Prius
    Model:
    Three
    My son and I drove our 240k mile Prius to California from NY. Made it to east side of LA and in traffic noticed some wierd shaking on engine start.
    Went to Claremont Toyota and they were awesome. The tech explained that there are head gasket issues , usually around 150k. He’d never seen one go over 200k without the problem.
    Car is extremely rusty (NY salt tax) so not worth putting $$$ into.
    Anyway, car still runs fine, just loads up cylinder when hit and engine off. We took the cap off overflow- hoping to alleviate the pressure when shut off, but still pushes water in cylinder and creates rough start.
    These were the first to not have a radiator cap- is there anything else to do to lessen pressure?
     
    #1 bob11x, May 19, 2025 at 10:42 PM
  2. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
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    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    The reason you're not finding a separate radiator cap on a gen 3 is that the gen 3 cooling system isn't the overflow-bottle style. The bottle you found is the degas bottle and it is a full participant in the cooling system and its pressure cap is the only one there is. When you take that cap off you have depressurized the whole system.

    If you're still getting juice in the cylinder with the system depressurized, the gasket is just that bad. Not great news, I know.
     
    #2 ChapmanF, May 20, 2025 at 9:11 AM
  3. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
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    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Stop-leak product till engine fails, sell for scrap?
     
    #3 Mendel Leisk, May 20, 2025 at 9:11 AM
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