Another head gasket or worse

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by tianmaire, Sep 12, 2025 at 5:36 PM.

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  1. tianmaire

    tianmaire Junior Member

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    TL: DR - my 2012 has 188k and the engine has been knocking occasionally upon start up. Dealer is saying either head gasket replace or worse case - engine replace ($6100). Also EGR valve for $750 (they just cleaned the ports recently and replace the intake gasket ($570) so why didn't they just do the whole job then!?)

    So I took my car back to dealer after the EGR port cleaning etc didn't fix the knocking. They found codes P0301 and P0302. Found low coolant level and excessive pressure in coolant tank. Performed "block test" which "failed", indicating need for a head gasket replace and cylinder head replace but won't know for sure until head is removed, of course. Then possible a full engine replacement. It also needs brakes ($700 per axle!?)
    They also mentioned 2 TSBs: T-SB-0169-16 (oil consumption) and T-SB-0027-16 (engine noise when starting after "cold soak".

    Do I give up on it, use Peddle and get maybe $1k? Do I drive it a little longer, knowing I can't fix or resell it and how dangerous is THAT?! Do I find a local shop and go forth with a 2nd opinion and possible new engine? The engines available in the area are all well over 100k miles on them and available from 1300-1900 (according one shop I've been talking with).
    I'm especially concerned after reading enough about 3rd gen issues to know the head gasket could fail again.
    I just hate giving up on a toyota without hitting the 300k mile mark ;)
    Both kind words and harsh reality checks welcome from y'all.
    Context - car was given to me by family member 2 yrs ago so besides about 1200-1550/yr in maintenance, I am not into the car too musch $$ wiser - I would not have chosen a 3rd gen but when someone hands it to you - you (I) take it!
     
    #1 tianmaire, Sep 12, 2025 at 5:36 PM
  2. Tombukt2

    Tombukt2 Senior Member

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    Gotta milk The cow slowly geesh! Good sense helps in this realm of things . Think a lil bit read etc . That's things ain't knew . The methodology is a lil different today . I mean we as a people believe a lot of things today just 30 years ago not possible . So beware . Many those beliefs created for a narrative . A certain dialogue . Etc . So when you talk to people now you have to record right down make a note of everything said so you can look back over wen that person or around . Then you can pick apart the dialogue not in front of them . And usually see how off rails things mite be getting . Of course if you're like same . Kinda like blind leading the......
     
    #2 Tombukt2, Sep 13, 2025 at 6:42 AM
  3. Mendel Leisk

    Mendel Leisk MMX GEN III

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    The knocking is the engine struggling to compress coolant in the combustion chamber(s).

    With long term neglect of the EGR system system carbon build-up prevents its proper function, engine overheats, unevenly, head gasket fails, coolant leaks, and here you are.

    At this juncture cleaning the EGR system, while a very good idea, is NOT going to somehow “heal” the leaking head gasket.

    Toyota is complicit in this mess: they rushed the system to production. Very evident in hindsight. And compounded the issue by not ‘fessing up.

    Who did the EGR cleaning, dealership? They’re typically not going to do it properly. Unless they just replace everything, which will set you back close to 2 grand USD.

    To clarify: by “another” head gasket, you’re meaning another head gasket case, chiming in, not that yours has had a previous head gasket replacement?

    The only way to avoid this nonsense is to thoroughly clean the full EGR system, that’s everything between the exhaust manifold and the intake ports, at least every 50k miles.

    (Apologies for Tom by the way, not sure what he’s on about lol. If you read his missives aloud it helps comprehension fwiw.)
     
    #3 Mendel Leisk, Sep 13, 2025 at 9:14 AM
    Last edited: Sep 13, 2025 at 9:25 AM
  4. Brian1954

    Brian1954 Senior Member

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    The knocking is not caused by the engine struggling to compress coolant in the combustion chamber. If that were to happen, the piston rod would be bent, or it would break. The knocking in most cases is caused by misfiring in the cylinder. There are many things that can cause misfires. In the case of a bad head gasket, coolant seeps into the cylinder and causes the spark plug to misfire. This has been pointed out to you many times. Why do you keep spreading bad information about what causes the knocking?
     
    #4 Brian1954, Sep 13, 2025 at 9:41 AM
  5. Mendel Leisk

    Mendel Leisk MMX GEN III

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    Either way, it’s coolant in the cylinder? Would that be good information?
     
    #5 Mendel Leisk, Sep 13, 2025 at 9:45 AM
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