How common is Gen 2 Head Gasket Failure after 300,000 miles?

Discussion in 'Gen 2 Prius Main Forum' started by PrimalPrius, Feb 6, 2026.

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  1. PrimalPrius

    PrimalPrius Member

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    I'll simplify the question: The only places where coolant can enter oil are:

    1) Head gasket

    2) Timing chain cover (RTV seal or damaged cover).

    3) Pipe plug in head.

    4) Crack/hole in head.

    5) Crack/hole in block.

    Surely someone here can confirm or dispute.
    I'm 99.9% sure, but the reason I am asking is to avoid that "Do'h! All this time it was actually leaking at the ____________!" moment.
     
    #61 PrimalPrius, May 9, 2026 at 11:10 AM
  2. rjparker

    rjparker Tu Humilde Sirviente

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    You act like this a game show. Jeopardy has prizes but, unlike you, the host has no risk.

    My guesses and answers:

    Diagnostic steps lead to answers:

    We can't see it, put our tools on it and are not getting paid to diagnose or repair. Pay somebody.
     
    #62 rjparker, May 9, 2026 at 11:55 AM
    Last edited: May 9, 2026 at 12:44 PM
  3. PrimalPrius

    PrimalPrius Member

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    You sound like a smart guy, but post some odd replies, at leat from time to time, in this case completely missing the question.

    The question is: Are the paths/interfaces listed the only places on a gen 2 prius where coolant can theoretically enter the oil?
    I think they are. There is no oil cooler in the radiator, for example.
     
    #63 PrimalPrius, May 9, 2026 at 12:50 PM
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