camshaft markings/valve timing

Discussion in 'Gen 3 Prius Main Forum' started by donzoh1, Feb 2, 2019.

  1. donzoh1

    donzoh1 Junior Member

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    P.S. I can also see that the small hook has sprung open toward the timing chain cover. When tight, the top segment of the chain rubs against the upper chain guide but some slack remains depending on cam position.
     
  2. Mendel Leisk

    Mendel Leisk Sidewalk Supervisor

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    You've watched around the 33 minute mark, in that video?
     
  3. ChapmanF

    ChapmanF Senior Member

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    I remember the video (maybe around the 33 minute mark) suggesting the tensioner gets the benefit of oil pressure behind it once the engine starts, in addition to its own spring, and the chain might sound a little slappy for a few seconds until that happens. Maybe the oil pressure will be enough to extend it one more click.
     
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  4. cnc97

    cnc97 Senior Member

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    The oil pressure will finish tensioning the chain on startup. It might move a couple clicks when fully pressurized initially.
     
  5. ChapmanF

    ChapmanF Senior Member

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    Kind of a clever design, that. They could accomplish the same thing just by making the spring stiff enough inside the tensioner, but then it'd be really hard to install by hand.
     
  6. donzoh1

    donzoh1 Junior Member

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    I see it as more of a design problem. Maybe it's not enough to damage anything. But, if a stiffer spring was used, it could be compressed with a vise or channel lock pliers. Or how about just a little more access in the timing cover where the tensioner is located? I'm guessing it's not enough to skip a tooth but that's the problem...I'm guessing.
     
  7. cnc97

    cnc97 Senior Member

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    If you want to be “sure” the chain won’t jump on initial startup, you can take a moderate size screwdriver and push toward the exhaust cam gear on the top of the tensioner. But as long as you can not lift the chain off the gear, it’s not loose enough to jump off the gear.

    That’s where the multiple rotations of the crankshaft come in. The tensioner provides a constant amount of spring pressure. The rotations ensure that all the slack gets taken out by the moving guide.
     
  8. donzoh1

    donzoh1 Junior Member

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    I have done multiple crankshaft rotations and i dont think the chain has enough slack to jump. I'm not understanding where you recommend pressing with a screwdriver though.
     
  9. cnc97

    cnc97 Senior Member

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    Anywhere in the circled area in this photo. Gently pry the guide toward the chain. Listen for the tensioner to click. If you get one or two clicks out of it, you will be good.
     

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    #29 cnc97, Feb 9, 2019
    Last edited: Feb 9, 2019
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