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Blown Head gasket rebuild....@297k

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by danlatu, May 8, 2017.

  1. schmuber

    schmuber Member

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    IMO lapping is the best way to visually confirm how the valve sits. And since I gonna have everything disassembled anyway, why not?

    That's the plan. The question is, should I lap with old seals or the new ones?…
     
  2. cnc97

    cnc97 Senior Member

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    Leave the seals off when lapping the valves. There’s really no need to have them on the valve when lapping them.
     
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  3. The Critic

    The Critic Resident Critic

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    The engine was running fine before the HG failed and there were no known valve-sealing issues, correct?

    If so, just leave it alone. Install new seals, check for straightness and reassemble.
    Take it to a machine shop to have the head cleaned and resurfaced would be ideal, but I certainly would not fuss with the valves if everything was previously working.
     
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  4. spiralhelix

    spiralhelix Active Member

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    Can’t an engine still perform fairly well with small leaky valves? Simply for the sake of having the engine torn apart, doing a brake cleaner valve check and fixing any small leaks seems more logical now than letting the problem get worse and having to do it later.


    -Spiral
     
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  5. schmuber

    schmuber Member

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    Right now the head is soaking in a tub of Simple Green. Once I finish with cleaning it, I'll literally inspect valve seats under the microscope and decide wether or not they need a bit of lapping with ultra fine compound. While the engine was working fine, at 240K I'd expect some pitting. And judging by how different they look (color/thickness of deposits), I'd say there were some developing issues.
     
  6. cnc97

    cnc97 Senior Member

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    The color and thickness of deposits is directly proportional to how much coolant/oil each cylinder was burning. Coolant deposits tend to flake off easily, where as oil deposits take more finesse to remove.
     
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  7. schmuber

    schmuber Member

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    How would that explain an extra oily goo in a cylinder 3 intake?
     
  8. cnc97

    cnc97 Senior Member

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    The PCV valve hose does dump into the intake directly below the passage leading to cylinder 3. That would make an engine with high blow by likely to ingest the oil primarily into cylinder 3. Although all cylinders would get some of the oil.
     
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  9. schmuber

    schmuber Member

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    Cleaned, slightly resurfaced, valves lapped, stem seals replaced. Ooooof.

    IMG_0966.JPG
     
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  10. The Critic

    The Critic Resident Critic

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    Do you have a solvent tank? How did you clean the head?
     
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  11. Patrick Wong

    Patrick Wong DIY Enthusiast

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    It looks like new.

    How about a photo of the bottom of the head so we can see the valves.
     
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  12. ASRDogman

    ASRDogman Senior Member

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    How off, if any, were the valves? Did you bother to check if they were sealing or did you just lap them?
     
  13. schmuber

    schmuber Member

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    Stripped of everything removable and soaked in a $5 plastic file bin with 50% solution of Simple Green overnight (edit: I'm talking about the head itself, not other parts). Hosed it off, then blasted the most stubborn stains with carb cleaner. Left the remaining stains alone.

    Valves look pretty much the same as when the head first came off. Carb cleaner removed oil deposits, so intake valves look substantially better… but the white residue on the exhaust side valves seems to be irremovable.

    I've inspected them under microscope in a good light and found some pitting, especially on the exhaust side. Nothing to be concerned about if it was a lawnmower or a bike, but since we're talking about Japanese puzzle box that took me 3 days to take apart… I lapped them lightly with the 800 grit compound. Pitting is gone, mating surfaces are like mirror now.
     
    #613 schmuber, Jul 18, 2019
    Last edited: Jul 19, 2019
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  14. ASRDogman

    ASRDogman Senior Member

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    The white is from heat, more than normal. I have seen this a lot of motors that have overheated.
    I've used a wire wheel on a bench grinder to clean them up.
     
  15. schmuber

    schmuber Member

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    Almost there, had to stop because it started raining nuts and bolts, I mean cats and dogs. Almost there though…

    Question. It seems that I was too enthusiastic with disassembly and took apart the entire engine mount. What's the torque for the bolt that goes through the dampener? Edit: nevermind, found it.
     
    #615 schmuber, Jul 19, 2019
    Last edited: Jul 20, 2019
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  16. schmuber

    schmuber Member

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    Aaaaalmost there! The oil is in, so far no leaks. Tomorrow will be installing the EGR system, intake manifold and trying to figure out which hose goes where (anyone has a decent pic of the hose that goes to water pump parallel to the engine? Where does it connect?)

    2019-07-20 23.45.28.jpg
     
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  17. IMkenNY

    IMkenNY Im just being nosy

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    Almost there!

    I rotate the completed engines 20 or so revolutions by ratchet just to get the oil circulating and check for any binding etc. before I push that start button.

    I've done ten plus major engine repairs/ swaps over the years and despite having great success I still get nervous starting these newly repaired engines every time.
     
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  18. Mendel Leisk

    Mendel Leisk Senior Member

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    Was listening to recordings of Neil Armstrong in Apollo 11, just minutes before they start the descent to surface burn. He says:

    "Okay. What else is left to do here?"
     
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  19. schmuber

    schmuber Member

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    That's a great idea! How soon do you change the fluids, by the way?

    It's my very first time, so I'm waaay out of comfort zone.
     
  20. cnc97

    cnc97 Senior Member

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    I ran mine 500 mile then changed the oil, then 3000(2500 more) then went to 5k interval.
     
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