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Headgasket replaced and failed shortly after? Do anything different next time?

Discussion in 'Gen 3 Prius Main Forum' started by AmazingFacts, Nov 5, 2021.

  1. AmazingFacts

    AmazingFacts Member

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    I'm about to replace the HG and have heard of HG failing again shortly after replacement. I've called a few repair shops regarding this and one shop won't even bother with HG replacement and will do an engine swap. Anyone have any insights and tips regarding this? I'm assuming HG fail again for the second time for the following reasons:

    1. Didn't check piston height for bent rods....and possibly hole or crack in block.
    2. Didn't check head and block for warpage with straightedge.
    3. Reused cylinder head bolts and didn't torque and in proper sequence.
    4. Used cheap HG instead of OEM Toyota or Felpro.
    5. Didn't replace water pump.
    6. Radiator clogged...possibly with HG sealer. Also didn't flush out coolant properly from coolant/HG sealer properly.
    7. Didn't leak test cylinder head.
    8. EGR/intake manifold/EGR valve plugged up.

    Anything else to add to the checklist?
     
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  2. rjparker

    rjparker Tu Humilde Sirviente

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    Oil consumption and miles would be my number 1 engine or no engine decision factor. If I did a hg only it would be with a rebuilt head from a qualified machine shop. Of course any of the points your list would have to be done right in either case.

    A lot depends on how long you will keep the car and how many miles per year. Fix it and sell in a couple of months? Or try to get two or more years out of it in a high mile per year usage case?

    Even the replacement engine choice has two options. Rebuild or as is. For me "use as is" would have to be a low mile 2015-17 gen3 US engine. Otherwise rebuilt.

    If I were in San Jose I would let Gasketmasters do it at their shop and get a guarantee. Nothing beats experience for doing it right. They can help you decide.
     
  3. Mendel Leisk

    Mendel Leisk Senior Member

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    I watched one video where the guy (describes himself as a "master mechanic") said something along the lines of: "I'm not sure if it's necessary, but I like to put a few drops of oil on the new head bolt threads". Repair Manual says oil the threads, and the space between bolt head and washer*.

    Anyway, Read up all you can. There's some repair manual excerpts linked in my signature, the "head gasket" ones.

    Also linked is @The Critic's thread, if you haven't found it already.

    * In "Cylinder Head Removal" pdf, linked in my siganature, under "head gasket...".
     
  4. AmazingFacts

    AmazingFacts Member

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    Thanks for the feedback. Mine has 250k miles and plan to keep it for 4-5 years. There's no oil consumption and getting 50 mpg city/highway with gentle driving.
     
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  5. AmazingFacts

    AmazingFacts Member

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    One more thing to add to the checklist would be to make sure oil doesn't pour into where the headgasket bolts goes. There will be some pooling of oil in the cylinder head area so be sure to soak up the oil before removing the bolts. If bolts are tightened with oil inside, it can damage the head and create a chain of failures. So take a quick peak inside each of the 10 holes with flashlight or boroscope before installing the bolts.
     
  6. Mendel Leisk

    Mendel Leisk Senior Member

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    Though the head bolts should have oiled threads, and oil between washer and underside of head.
     
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  7. AmazingFacts

    AmazingFacts Member

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    Another thing to add: Make sure no critters make a nest or burrow in any openings (coolant hoses, fuel lines, etc), if you're taking more than a day on the project. Block off the holes with rags, etc.
    Also this is a good time to inspect and clean fuel injectors and install a oil catch can if you haven't done so yet.

    So far, I was able to remove the head and inspect for warpage on the block and head (with one of these aluminum straight edges from Amazon POWERTEC 71213 Anodized Aluminum Straight Edge Ruler | 18" | Metal Straightedge Machined Flat to Within 0.001”) and .004 feeler gauge. Block is straight but cylinder has a very slight warpage towards the edge. Will have machine shop take care of that this week, along with possibly have them install new valve seals and lap the valves.

     
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  8. Mendel Leisk

    Mendel Leisk Senior Member

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    How much is the variation? Here's the spec (and more complete excerpt attached:

    upload_2021-11-7_11-46-19.png
    That last sentence; Toyota doesn't recommend machining?
     
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  9. AmazingFacts

    AmazingFacts Member

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    Ok thands Mendel.
    The cylinder block side passed the .05mm, but didn't pass the .04mm.
    Intake manifold side passed the .1mm.
    Exhaust manifold side passed the .1mm as well.

    So looks like I'm good. Should I still take the head to the machine shop? Maybe not machining, but maybe a clean, leak test and check if the valves need lapping?
     
  10. AmazingFacts

    AmazingFacts Member

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    Another tip: When checking for cylinder head/block/manifold for flatness, use BOTH sides of the straight edge. One side may not be true as the other.
     
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  11. Mendel Leisk

    Mendel Leisk Senior Member

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    Sorry, no hands on experience. :unsure:

    oh, linked in my signature, is @the Critic’s head gasket thread; there’s discussion of machine shop.
     
  12. rjparker

    rjparker Tu Humilde Sirviente

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    Absolutely take the head to a machine shop.
     
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  13. ChapmanF

    ChapmanF Senior Member

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    If one side of the straightedge shows it's flat and the other side shows a gap, which side do you believe?
     
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  14. burrito

    burrito Active Member

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    That wouldn't surprise me since it came from Amazon. At a B&M store, you can hold one up against the shelving or anything else prior to purchasing. I always check levels before purchasing, as well. Hold it against anything stable and check the position of the bubble, then spin it, flip it and check again. If the bubble changes position, it isn't level!
     
  15. OptimusPriustus

    OptimusPriustus Active Member

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    I think he meant hydrolock type of thing. Not the oiling of bolt threads
     
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  16. ChapmanF

    ChapmanF Senior Member

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    If it doesn't lie flat on the shelving, which do you conclude isn't straight?
     
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  17. Mendel Leisk

    Mendel Leisk Senior Member

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    I was looking at my assortment of levels, aluminum rails, slotted angles, thinking: if I just lay them out on a table, put some of them edge to edge and check for gaps with a feeler gauge, I should be able to sort out if one or two of them are pretty good.
     
  18. ASRDogman

    ASRDogman Senior Member

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    That is "nice person"uming the table is straight... :whistle::whistle::whistle:

    Maybe lay some dental floss out and tie the ends to nail hammered in something to hold them firm.
    And have some clean glass between them. Then lay the straight edge close to the floss and have
    a light shining through. Then you could see if light shines through. Not exactly perfect, but at least
    you would know the floss is straght, if it's tight.

     
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  19. Mendel Leisk

    Mendel Leisk Senior Member

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    I'm not sure the table is a factor, if it's just supporting to straight edges lying side by side. If you press two items gently together, then test with feeler gauge?

    19AC32A2-AEAF-4FB8-A2DF-E82B4D4BF5C2.jpeg

    the slotted angle tested very straight btw: pressed against the long level 2/1000” feeler wouldn’t pass anywhere along its length.
     
    #19 Mendel Leisk, Nov 8, 2021
    Last edited: Nov 8, 2021
  20. ASRDogman

    ASRDogman Senior Member

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    I guess you could flip ends of one. And if there is no gap, I guess both of them would be straight.

     
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