2007 Prius Oil On Spark plug..

Discussion in 'Gen 2 Prius Main Forum' started by GenoJ, Jan 13, 2017.

  1. GenoJ

    GenoJ Junior Member

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    Hey all!! I just changed my spark plugs and one of the cylinders had oil in the plug hole.. Looked with a mirror and couldn't see any cracks.. Anyone know whats going on with this?? Engine has 230,000 miles and its been about 75,000 since i changed them last
     
  2. JC91006

    JC91006 Senior Member

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    If nothing is wrong with it, just put new plugs and continue driving
     
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Either the cyl head gasket has a leak or that plug was loose in the threaded hole...
     
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  4. edthefox5

    edthefox5 Senior Member

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    Or it may be cylinder #1 and oil got spilled on last oil change and got under the cop
    Or the oil scavenge ring on that particular cylinder is toast. If your car uses oil that's where it's going. May have blue smoke out the exhaust too.
     
  5. GenoJ

    GenoJ Junior Member

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    Yes edthefox.. It does use oil.. No smoke out the exhaust but it does use oil.. For about the last year, I had to put in a quart about every month.. mpg was good up till a couple weeks ago now mpg has plummeted.. What is oil scavenge ring? The piston rings??
     
  6. valde3

    valde3 Senior Member

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    If oil is inside the spark plug hole it really can only get there from either by accidentally pouring it over the engine or valve cover that’s leaking.

    -If oil looked clean it was probably it probably was just poured there by accident.
    -If oil looked like used oil then it was probably leaking by valve cover gasket. There are to parts in valve cover gasket. Outer part stops oil from leaking into the sides of engine. Inner part keeps oil from leaking into the spark plug holes.
     
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  7. edthefox5

    edthefox5 Senior Member

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    I've owned a lot of cars with plugs through valve cover and most of them had the valve cover gasket around that s plug hole or a separate additional gasket to seal the plug hole through the v cover.
    I have never had the v cover off a g2 so maybe someone can weigh in if that's the way his cover works because that gasket failure at the,plug hole is th main reason oil gets in the s plug hole.
     
  8. DGESSWIN

    DGESSWIN Junior Member

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    What ever happened to this ? Was it the gasket?
     
  9. M in KC

    M in KC Active Member

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    From the VC gasket images online for the G2 Pri there does appear to be integrated spark plug tube seals as part of the VC gasket. I as well haven't pulled the VC on my G2 Pri only looking at the online images. Thru the VC spark plugs have been known to leak oil in other models. Depending upon sealing designs some leak from the tube where it is fitted into the head others are the gasket itself or both.
     
  10. DGESSWIN

    DGESSWIN Junior Member

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    image.jpeg image.jpeg This is what I'm dealing with. Right now.
     

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  11. Mendel Leisk

    Mendel Leisk Sand Pounder

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    There's oil all around, in the camshaft/rocker arm area, and IIRC a gasket to prevent oil getting down into the spark plug tube? Maybe that gasket is just drying out, not sealing?
     
  12. DGESSWIN

    DGESSWIN Junior Member

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    Yeah, I may need to tear it down and fix it. Still thinking about it. Car is missing and gas mileage is down.
     
  13. DGESSWIN

    DGESSWIN Junior Member

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    I bought the valve cover gasket. Should be here on Monday. I will certainly take pics and try to do a write up. I hate doing documentation, but I feel I owe it to this amazing Forum!
     
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  14. Mendel Leisk

    Mendel Leisk Sand Pounder

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    The "Plug Tube Gasket" might be the culprit:

    upload_2017-7-20_16-31-32.png
    This is 3rd gen, but likely similar.
     
  15. DGESSWIN

    DGESSWIN Junior Member

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    Don't tell me those are the things that come out when I pull out my coil packs....? Because they all come out.
     
  16. Mendel Leisk

    Mendel Leisk Sand Pounder

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    No, those are gaskets in the valve cover, likely installed from the inside.

    It could be one of the existing is just a little off-kilter? If that is the way oil's getting in, I wouldn't sweat it too much.
     
  17. Naurill

    Naurill Junior Member

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    I have just changed my spark plugs at 111k. The left hand one was oily. As it is closest to the oil filler, it is most likely that it was from an oil spill during an oil change. The car runs very smoothly now -- very different to before. I hope it leads to an improvement in fuel efficiency too. N
     
  18. edthefox5

    edthefox5 Senior Member

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    Is that plug oil soaked at the firing tip because the hole was full of oil and it got wet pulling it out or is it oil soaked because the cylinder rings are gone? The other plug looks like it was sitting in standing water as there's a rust line around the plug porcelain so that engine has had a rough life.

    At the very least the cop that was siting in that level of oil or the one that was sitting in that level of water is probably blown. Did you look in the spring hole of the cop to see how corroded the spring tip end was?
     
    #18 edthefox5, May 26, 2018
    Last edited: May 26, 2018
  19. edthefox5

    edthefox5 Senior Member

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    No theirs not a rubber insert at the top of the sp hole on a G2 its all steel. Steel top steel hole. Only the cover gasket has o-rings attached to the main gasket seal to seal that plug hole.

    I found on my car the valve cover hold down bolts were all really loose. Didn't come that way from the factory but the rubber gasket and yes its rubber flattens out after years of use. I tightened mine up. I will see if that stopped the oil ingress I had in cyl #3 as I have all the parts to change that cover gasket soon.

    To the OP tighten up the valve cover screws. Not crazy tight as your up against rubber gasket and if your too tight it will damage it.
     
  20. Atharmiac

    Atharmiac New Member

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    Hi Ed! I’ve been reading about this oil issue and I made an account to message you. I have some questions. I don’t understand all of this car lingo is there a way to message you directly? Sorry
     
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