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Head Gasket Engine Rebuild?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by SuperSqrl, Jan 19, 2023.

  1. SuperSqrl

    SuperSqrl New Member

    Joined:
    Jan 19, 2023
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    Location:
    Michigan
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Advanced
    Unfortunately....I've joined the Gen3 Head Gasket club at 180k miles with my 2012 PIP. I've been browsing the forums for a few days now, but I haven't quite found what I'm looking for (this post seems to be the closest). The main concern is, since everything is already taken apart, should I move forward with rebuilding the bottom half of the engine purely as preventative maintenance, and if so, how far down the rabbit hole should I go?

    The things holding me back are as follows:
    • No oil loss/burning, so isn't yet necessary
    • I'm working on pretty limited space in my single stall apartment garage (not sure how an engine hoist / stand would fit in there).
    • It would likely be another 1-2 weeks waiting for parts/etc, whereas I could get everything back up and running on Saturday if I just bundled it all back together
    • This HG is my first foray into engine work, so I'm limited in experience. That said, the only way to learn is by doing, and I figure as I take my time and do the proper research (Repair Manuals included), I should be good to go. But I know there's a lot of "can't screw this up" procedures to it.
    However, here's what's making me even consider going to this depth (pun intended):
    • Since we're almost 200k, we won't have to worry about doing this again if oil burning does become an issue, and more peace of mind about the overall state of the engine
    • Since the short block is already exposed, it's not a crazy amount of work to do
    • I've heard of several people who have blown holes in their engine block starting ~225k miles, which would make me really sad to do all of this work and have it do all of this work again so soon.
    • Cylinders 3 and 4 along with exhaust valves and spark plugs are white (the HG failure was on Cylinder 1). I'm guessing this means things overheated and possibly weakened even though I stopped driving as soon as the failure was apparent (lost coolant and misfire on initial startup or after sitting for 30 seconds at a stoplight), and no temp lights ever showed. Worth noting, the head is not warped and is in great shape overall.
    If I did move forward, there's two approaches:
    1. Replace only the necessary parts (ie, bearings and rings)
    2. Upgrade pistons/rings to the 2015 version to effectively "bulletproof" the engine
    I figure if I go all out, I could see another 200k out of the car (even when the Lithium battery dies), but I don't know where to draw the line here, or if I should take more of a "if it aint broke don't fix it" approach. Once we're at 300k, I imagine it'll be a lot more than just the engine to worry about.

    The first approach would cost ~$500 for bearings / rings / thrust washers, whereas the full piston rebuild would be $1300 with Pistons/Rods (a short block is running $2250 right now). Between Timing Chain/HG/machining/etc, I'm already around $700 invested in parts alone.

    Also if there's anything else I might be missing, feel free to mention it!
     
  2. SuperSqrl

    SuperSqrl New Member

    Joined:
    Jan 19, 2023
    2
    0
    0
    Location:
    Michigan
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Advanced
  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
    Just replace head gasket and leave the block alone?

    be sure to clean the full EGR circuit.