How do I piston soak? Only 1 cylinder fills up.

Discussion in 'Gen 2 Prius Main Forum' started by Bunce, Nov 3, 2018.

  1. Bunce

    Bunce Member

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    I've just pulled the plugs and poured in some marvel mystery oil. Only 1 cylinder filled up, I could hear the others just pouring through.
    How do I get the other 3?
     
  2. ChapmanF

    ChapmanF Senior Member

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    That sounds like there might be more ring or cylinder wall damage there than a piston soak will be able to solve. What prompted you to try a piston soak? What compression or leakdown readings do you have?

    Are you pouring into cylinders when the pistons are at TDC?

    -Chap
     
  3. Bunce

    Bunce Member

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    No idea if it's at TDC. How do I tell?
     
  4. padroo

    padroo Senior Member

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    Easy way to tell if a piston is at TDC is to drop a long screwdriver into the cylinder by way of the spark plug hole and rotate the engine until it starts to go back down.
     
  5. Bunce

    Bunce Member

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    How do I rotate the engine?
    It's in a tight parking spot right now and can't be moved until I put it back together.
     
  6. Bunce

    Bunce Member

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    Also, would they all be at TDC together?
    Why can I fill 1 up but not the other 3 if so?
     
  7. bisco

    bisco cookie crumbler

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    No, they each fire alternately
     
  8. bisco

    bisco cookie crumbler

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    Usually, you find your way to the nut on the front of the crankshaft to spin an engine. I’m not sure if Prius is similar
     
  9. Bunce

    Bunce Member

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    I managed to find my endoscope. There is MMO in all of the cylinders but for some reason on Cyl 3, it filled the spark plug hole. So it must be sealed up pretty damn well. Does that mean it's right at the top of it's stroke?

    I'll let it sit overnight then blow out the remaining by starting it without plugs and then put it all back together. Check the level, as long as it's below full, do an Italian tune up and then an oil change with Mobil 1 5w 30 high mileage oil and an OEM filter.
     
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  10. Skibob

    Skibob Member

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    Good advice but I would recommend a wooden dowel instead of a screwdriver. ;)
     
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  11. Skibob

    Skibob Member

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    What is an “Italian tune up”?
     
  12. Bunce

    Bunce Member

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    Drive it hard.
    Tough to do when you can't control gears but, flooring it up long steep hills to get it nice and hot should get the job done.
     
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  13. Skibob

    Skibob Member

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    Personally if I were to piston soak I would want all of the bores at the center of the stroke. Is a 1.5L Prius engine a flat or cross plane crank?
     
  14. Skibob

    Skibob Member

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    I agree. Sounds like what you have to do with a high performance engine. Like the original 911S. They just foul up if you drive it like a grandma
     
  15. Bunce

    Bunce Member

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    I think that's part of the problem with Prii and the oil burning issues, the drivers typically dordle around and the engines don't get driven hard enough. They don't get hot enough to burn all the crap that accumulates inside engines.
     
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  16. Bunce

    Bunce Member

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    Well the soaks done, the oil's changed. We'll see if any oil disappears.
    On a side note, the pistons are completely black. I could not see any bare metal on the face of them.

    I'm wondering if sucking in some water through a vacuum tube into the intake (while the engine is running) would help get rid of some of that gunk?
     
  17. Mendel Leisk

    Mendel Leisk Lapsed Cargo Cultist

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    Though a screw driver probably would be fine, I had the same thought. You could mark gradations on a dowel too, might help.

    Dowels are also handy to have on hand, for pushing a rag through a funnel, to clean it, stuff like that.

    Either angle out the front/passenger wheel, or remove it completely. Then look in behind: you need to get a socket and ratchet on the nut at the end of the crankshaft. I took a quick look at ours (albeit 3rd gen) and there doesn't appear to be an opening in the plastic splash-shield, so guess it would need to come off.

    I've never done it on our Prius; various Hondas over the years always had a small opening there. The Honda's were always screw-and-lock-nut valve adjustment, and that requires turning the engine over.
     
    #17 Mendel Leisk, Nov 5, 2018
    Last edited: Nov 5, 2018
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  18. sam spade 2

    sam spade 2 Active Member

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    Better off to LEAVE IT ALONE.
    And a much easier way to apply MMO is to drizzle it into the intake while the engine is running.
     
  19. Bunce

    Bunce Member

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    I wanted to soak the carbon deposits not just burn the MMO off. But, that's what I want to do with water, as that's supposed to clean the best.
     
  20. Skibob

    Skibob Member

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    My friend did that with his Miata, when he took it to get smogged it passed like a new car. Ran better too.
     
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