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Head gasket vs engine, a few questions

Discussion in 'Gen 3 Prius Technical Discussion' started by IndianaJim, Apr 17, 2024.

  1. IndianaJim

    IndianaJim Junior Member

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    Hi all.
    I have a few questions after searching the subject for a few days.

    we have a 2012 with 238,000 on it.
    It’s been using a small bit of coolant (like a few ounces) the last few oil changes, but last week I got a cylinder 2 misfire code. Thinking it was just that, I replaced plugs and coils, as the coils were original, and #2 seemed to have an arc mark on the boot.
    A few days later the code came back, and the coolant is down again, which now leads me to believe head gasket failure.

    I was originally going to just do an engine swap, but getting a good one isn’t what one might call cheap, though my local yard has a Gen 3 with 139,000 for $2400. I won’t go the Gen 4 route.

    Then I got to thinking about the head gasket/oil usage of a replacement, and got to thinking head might be the best route. it would certainly be cheaper, even if I got a reman head.
    The current engine uses between 1/4 and 1/2 quart fairly consistently between oil changes which are 6-7000 miles with Mobil 1 0w20 AFE, so certainly not excessive and quite a bit less than what seems “normal” here.

    I have concerns about possible engine damage from the leak in the form of a bent rod though.

    FINALLY the questions!
    I think I should be able to tell a bent rod by a compression test, but would like confirmation.
    If I have a bent rod, all of this doesn’t matter much.

    Assuming I can do just the head, is it best to have it gone through (or even get a rebuilt head) or just checked over?
    if rebuilt, is there a known good place to get one ready to go that you all recommend?

    If engine, some mention doing the head gasket as a preemptive procedure. Is it worth it?
    we need the car about one more year, but would like to get two, which means about 60,000 more miles.

    no matter what, I plan to replace the water pump and probably the egr cooler too, or at least clean it, but I believe Toyota did that when we had the intake replaced due to buildup (their diagnosis and fix, and they mentioned egr).

    Anything else I’m missing about this?
     
  2. Tombukt2

    Tombukt2 Senior Member

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    I think you can buy the reciprocating mass for this engine ready to go for like $1,300 somewhere in there then bolt your girdle your pan your timing cover I've seen remanned heads actually in the $400 range I'm not sure if that's with cams or not your cam should suffice. Then of course that assembly is balanced and all of that business ready to go check your cam phaser and get your timing all set up and you should be good to go.
     
  3. IndianaJim

    IndianaJim Junior Member

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    I don’t think I’d do a short block. If I were that far into disassembly, I’d just rebuild it myself at that point.
    I’m going more for speed of repair, or rather minimum downtime, vs longevity.
    Right now I’m going to do the compression test, and go from there I guess.
     
  4. ASRDogman

    ASRDogman Senior Member

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    IF you caught it early enough, you shouldn't have a problem with the
    head or rods. You can measure the piston heighth with the spark plugs removed.
    When you have the head off, lay the head on a clean dry rag, then spray some wd40
    into each intake and exhaust port and wait about 5 minutes. Then carefully lift the head
    and check for leaking valves. If all are dry, don't mess with it. If you see the wd40 leaking through,
    then you need to seat the valve in with valve grinding compound. Since you're going to
    replace the valve guide seals anyway, you might want to do it anyway. And clean any
    carbon off the valves also.

    Clean the piston tops off while you're at it. The engine doesn't seem to be burning any oil
    so the block should be in good shape.

    You can clean the egr cooler with oven cleaner and a pressure washer and clean out the
    ports for the intake with a .22 cal. bore brush and gunk and a drill.

    I have 34,000 miles on my new head gasket.


     
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  5. IndianaJim

    IndianaJim Junior Member

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    Just finished measuring the piston height with my custom made tool, lol.
    All looks great on that end.
    The “tool” is an M12 x 1.25 (spark plug thread) to 1/4 npt fitting, a 1/4” female to female, a 6” piece of 1/4” pipe, another female to female, and a 1/4” air hose fitting. This will allow a 3/16” diameter rod to slide fairly easily through it, and gives a nice edge to measure from to the top of the rod. Obviously this could be modified to one’s liking.

    I’m now debating replacing the timing components while I’m there, as the stretch test seems a bit harder to measure, though I suppose I could attempt the measurements with it in place before removing.
    If I replace them, should I go with OEM Toyota or something good aftermarket (if such a thing exists)?
     
  6. rjparker

    rjparker Tu Humilde Sirviente

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    You have to take the chain off anyway. Getting it back on properly if the usual problem since you can’t tension it until the cover is back on.

    Prius gen 3 timing chain max length.jpeg
     
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  7. heh

    heh New Member

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    I was told that I needed a head gasket repair on my 2015 prius. I opted with a new used engine instead. Once they got it in, the hybrid system would not kick in so they car would not start. Another shop told them to disconnect the a/c compressor and then the car started and ran. It is not even close to how well it ran before. I now have it in the shop to get the compressor fixed so that my air conditioner works, and figure out why my gas mileage is terrible. I wish I would have just done the head gasket, or junked the car. I have over $9000.00 into fixing it and now they want 1200.00 more. The car was $8000.00 when I bought it about four years ago.
     
    #7 heh, May 1, 2024
    Last edited by a moderator: May 2, 2024
  8. ASRDogman

    ASRDogman Senior Member

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    Obviously the shop doesn't know what it's doing.
    And when you get a used engine, it's always a gamble. It's not a good idea.
    If that engine is bad, it's not the fault of the shop. If the are the ones who got
    the used engine for you, then they are responsible for it and will have to get you
    another one, that hopefully works, or give you your money back.
    If they didn't install it correctly, that's on them.
    Did you get your original engine back? Maybe replace the head gasket, it's very
    easy now that it's out of the car. And have them swop it back.
    Or get the car to a place that knows how to do the job correctly.

    Possible the only other course of action is to get a lawyer...



     
  9. rjparker

    rjparker Tu Humilde Sirviente

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    The first shop got the ac compressor mating connector dirty which causes a high voltage leak. Fairly common.

    Where did the used engine come from? A junkyard or a JDM engine dealer? Did your shop rebuild an engine? For that money they should have. I would respectfully ask them to cover all repairs or give your money back. When that fails have a lawyer draft and send a certified Demand Letter. This is not a lawsuit. Yet.

    Listing your location helps. Where in the US are you? You might get recommendations on where to go. This forum is primarily populated with diy guys who think everyone should do it themselves. But there are options like having a quality rebuilt engine shipped to a shop for installation and still save $3k-$4k.

    Bottom line - in most states it is buyer beware with little legal recourse. Most regular shops are clueless on hybrids. Sometimes it is better to drive 2 hours to get quality at a value price. Some of us can give you good advice but you do better by asking first.

    For better results on forums:
    Start your own thread - write all the details - don't ask questions at the end of other threads with little context. Answer all questions you get promply.
     
    #9 rjparker, May 2, 2024
    Last edited: May 2, 2024
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  10. IndianaJim

    IndianaJim Junior Member

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    I’m part way into tear down, and no issues yet, other than getting to some of the bolts/nuts by the inverter side.
    tackling the timing cover tonight after work, and hope to have the head off tonight too if all goes well.

    I decided to just replace the chains, guides, and tensioner, as it wasn’t too expensive for the parts vs taking mine out, then measuring and possibly having to wait to get the parts for several days.
    At nearly 240,000, I figured why not, it won’t hurt a thing.

    Stories like the poster above make me glad I have the ability to do these kinds of things myself. I find it hard to trust many shops, and feel for those that are at their mercy.
     
  11. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Buying a car and expecting the manufacturers to stand behind them is becoming more and more of a crap shoot. Maybe it’s always been thus? The world needs somone like Ralph Nader on this, for:

    1. thorough testing of new vehicles prior to retail production.

    2, reliable, reasonably priced parts supply, with counterfeit policing.

    3. Crack down on preposterous measures needed for common repairs.

    4. Incentives to car makers who concentrate on sensible/practical, lower cost vehicles.
     
  12. rjparker

    rjparker Tu Humilde Sirviente

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    We live in the US where freedom for trolls and scammers has grown to anything goes for businesses. Buyer beware. I try to warn people about gen3 but too many here are apologists. Until it happens to them like Bisco.
     
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