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2010 Head Gasket replacement - questions before reassembly

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by bdc101, Oct 22, 2023.

  1. bdc101

    bdc101 Member

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    Ok, all three of these photos were taken at the same time (without rotating the crank at all). Is my timing sure to be good based on this evidence ? Or do I need to remove the timing cover to check the colored link on the crank pulley?

    Your continued help is much appreciated...!!!

    PXL_20231127_023443497.jpg PXL_20231127_023440079.jpg PXL_20231127_023435536.jpg
     
  2. bdc101

    bdc101 Member

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    FWIW, apparently I had two o-rings on that one fitting between the valve cover and the intake cam phaser. One was stuck to the valve cover and then one that stayed on the cylinder head was cut in half.
     
  3. bdc101

    bdc101 Member

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    Further elaboration... With the crank in its position shown, the exhaust cam mark is almost at its top dead center, and the intake cam mark is about two teeth ahead of its top dead center. Just wanted to elaborate since it may not be perfectly visible in the pics.

    I understand that ASRdogman says regardless of the painted links, when the crank is at TDC the cam sprocket marks should line up with something, I just don't know what. There are no marks on the cylinder head to guide me. The factory manual doesn't show any marks either, it just has a picture with the marks in roughly the same place that I do.

     
  4. rjparker

    rjparker Tu Humilde Sirviente

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    I think your marks look good including the harmonic balancer. I would fix the oil passage orings and test drive again.
     
    #64 rjparker, Nov 26, 2023
    Last edited: Nov 26, 2023
    bdc101 likes this.
  5. ASRDogman

    ASRDogman Senior Member

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    Okay, do you see where the marks are, where the chain fits? Look at it in relationship to the
    cam cover. THAT is where they should line up when you are on TDC for the
    INTAKE stroke of cylinder #1. No matter where the colored marks are.

     
  6. bdc101

    bdc101 Member

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    This duplicate post brought to you by PriusChat.com
     
  7. bdc101

    bdc101 Member

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    I put it back together with the one O-ring that wasn't trashed (didn't look great but didn't look terrible either) and buttoned it up. Will drive it around tomorrow a bit and see how it does! Got the underbody put back together tonight as well, but didn't have time to put the wiper cowl on. Fortunately I live in the desert so no precipitation is expected anytime soon.
     
  8. Mr. F

    Mr. F Active Member

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    The intake and exhaust camshafts are correctly timed to each other, but until you verify that the yellow mark plate on the chain lines up with the timing mark on the crankshaft sprocket, it would be impossible to say for sure whether the camshafts are correctly timed to the crankshaft—you would indeed need to remove the timing cover to check this. It does "look" correct assuming the chain is properly tensioned.

    I am not sure if I would be able to follow ASRDogman's instructions to set the timing. Those instructions seem to boil down to "Orient the camshafts exactly as in this picture while cylinder #1 is at TDC", and are problematic for the following reasons:
    1. there are no objective guidelines to help the installer judge whether or not the orientation matches what is shown, and
    2. even if the camshafts are oriented perfectly, allowing slack in the chain in the wrong locations will result in incorrect timing.
    I still don't see any reason why anyone would set the timing without the aid of the colored links on the chain (or alternatively, by counting the links between the timing marks on the sprockets).
     
  9. ASRDogman

    ASRDogman Senior Member

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    For some reason, you are not comprehending what I am stating.
    I have not idea how to get you to understand. I could not explain it any easier.

    Hundred's of thousands of engine's have been timed without colored marks, and check
    to make sure the timing is correct. The colored link are ONLY their for putting the on,
    not after the engine has turned 1 or more revolustions.

     
  10. bdc101

    bdc101 Member

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    I read and thought on this more last night and still can't find any way to accurately time the engine without the links.

    I think, ASRDogman, that you are slightly confusing the factory service manual's instructions (attached by rjparker on the previous page). When reassembling a disassembled engine, it says to put the cams in and line up the marks "as shown in the illustration." But it just provides the general location of the marks. There are no identifying features on the head that allow you to position them exactly, and that's ok because that is not the last step in timing the engine. (Many engines have indeed been timed without painted links, but I can't see how this one could due to the absence of marks). The next page, when putting the chain on, it shows you how to put the timing chain on and the links will ensure that the cams and crank are perfectly aligned.

    The general location of the marks that the FSM shows tells you to put the cams on before the timing chain is installed are not exact but will get you close enough that they are off by no more than one link. Then, putting the chain on will ensure that they are correct. I think this is the sticking point here that we have all been getting wrapped around the axle with.

    That said, having done this three times now in the past two weeks, I don't think I could say for sure if the timing was right without the painted links being on the correct places. For the simple reason that there are no identifying marks on the cylinder head area to say so. I could say they are in the correct general area but I wouldn't trust that they are right just by sighting the marks in the general area shown in the tiny illustration in the FSM. If I was assembling the engine with a timing chain that had no painted links, I would not trust myself to be able to do it.

    Timing chain stretch, the amount of tension, wear on the guides, and resurfacing/milling of the head can all affect this alignment and when you get down to it, the correct way to time the engine is whether there are the correct NUMBER of LINKS between the three sprockets.

    That is the conclusion I have come to -- I hope I made a bit of sense!
     
    #70 bdc101, Nov 27, 2023
    Last edited: Nov 27, 2023
  11. rjparker

    rjparker Tu Humilde Sirviente

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    You can time it without colored links when the chain is fully exposed by counting the links as shown in Saneauto’s video (post 55) above. 9 on top, 25 on the right side. At that point you could mark them.
     
  12. Mendel Leisk

    Mendel Leisk Senior Member

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    For me a testament of video value is "have I downloaded this", and yup, I had.

    My drill, involves VLC Media Player:

    1. In browser, copy address of the Youtube video
    2. Start VLC Media Player
    3.Pulldown: Media>Open Media Stream
    4. Paste in "network URL" field. *
    5. Pulldown: Tools>Codec Information
    6. In Codec Tab, copy field "Location"
    7.. In browser, open new tab and paste
    8. Previous video will be there; right-click it and choose "download"

    * Every so often this stops working, apparently due to some revision at Youtube. When it happens, searching will usually find an updated config file for VLC Media Player.

    This is getting to be a go-to thread for chain install, btw.

    Oh, and subscribe to that guy's channel, helps him out.
     
    #72 Mendel Leisk, Nov 27, 2023
    Last edited: Nov 27, 2023
  13. bdc101

    bdc101 Member

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    Indeed you could, if you knew the number of links (though that is not published anywhere in the FSM, at least that I saw).

    My local dealer had the O-ring in stock so I am gonna pick it up later today. Unfortunately the car threw the P0016 again this morning while taking the kids to school. I'll swap a brand new O-ring in and see what happens.

    Car stinkin' drives great though. Rides really good. The engine sounds and feels strong. Feels like a big car inside, but handles like a smaller car, and turns on a dime. MPG is averaging 42.5 since I got it running (including lots of idling when I started it up). It doesn't feel at all like a car with over 260k on it.
     
  14. ASRDogman

    ASRDogman Senior Member

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    This is where you are gettind confused.


    They do show you where each cam goes, BEFORE you install the chain.

    I have been trying to get you to understand that AFTER installing the timing chain.......
    You do NOT need those colored links any longer.
    Those colored links are for INSTALLING the chain.

    Soooooooo AFTER You've installed the chain, you will notice WHERE the cams are, AFTER................
    you've installed the chain.

    Then AFTER you install the timing cover, and tensioner, and AFTER you released the tensioner...
    you can (SHOULD) rotate the engine twice, 720 degrees. The mark on the pully should be at "0", zero....

    If the chain did not slip a tooth, and the marks on the cams and crank had the colored link in the correct spot,
    when installing it, you will be able to tell if the timing is STILL correct and has not skipped a tooth.

    HOW do you do that????? By looking at the cams and see if they are in the SAME place they were when
    you installed the timing chain onto the sprockets.

    NO, there are NO marks on the cam cover, but you do not need them. Just notice where they are when you
    put the chain on.

    I locked the cams in place before I took the chain off, so they didn't move.
    But I also noticed WHERE they where, so if they had moved, I knew where to put them,
    so it would be easier to install the chain. And if it was off, I'd be able to remove the tensioner,
    and move the chain off the cam and move the cam and put the chain on, WITHOUT having to
    remove the timing cover!

    But when I rotated the engine twice, 720 degrees, AFTER installing the timing chain cover and released the tensioner, the cams where in the correct spot. The engine started, rattled until the oil filled the lifters and has been running smoothly for just over 18,000 miles.

    And since yours is running smoothly, the timing must be correct. It's the other issues you need to be
    concerned with and resolve them..
     
  15. bdc101

    bdc101 Member

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    The FSM posted earlier in this thread just has a small, grainy picture that says to "align the marks as shown in the illustration." There are no marks on the head to align the marks on the sprockets to, like we have discussed.
     
  16. ASRDogman

    ASRDogman Senior Member

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    You aren't reading the whole post.
    And not understanding.....
    "
    NO, there are NO marks on the cam cover, but you do not need them. Just notice where they are when you
    put the chain on."

    "By looking at the cams and see if they are in the SAME place they were when
    you installed the timing chain onto the sprockets."

    I'll just take have to except you don't want to understand. You're too hung up on the colored links....




     
  17. Mr. F

    Mr. F Active Member

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    The timing marks do exist, but the other marks being referred to do not on a stock engine. This is throwing everybody off.

    If one were to create those marks on the head or valve cover, perhaps by a paint marker, they would first need to ensure that the timing was set correctly. But most people have the timing cover off because they're in the middle of a HG job, or because they want to check the timing, so this method doesn't help them because those imaginary marks don't yet exist. And most people probably wouldn't want to simply eyeball the positions of the timing marks on the sprockets and go "That looks about right" at the risk of having to take the cover off again for a redo.

    Once the timing has been set correctly, those marks could be created, and they could help verify timing after it had first been set correctly using the colored links (or by counting links between the timing marks), and people wouldn't have to eyeball the positions anymore and could instead confidently say "The timing marks on the sprockets now line up exactly with the marks I'd put in the last time I had the timing cover off".
     
  18. ASRDogman

    ASRDogman Senior Member

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    No eye balling needed. You can see by where the cam is. Where the lobs are.
    Move the cam one tooth either direction and the lobs are off...
    It's just not important anymore.

     
  19. bdc101

    bdc101 Member

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    Took the car out today and picked up the O-ring. Threw the code again but driving good. I find this car really fun to drive, especially trying to keep the ICE off. My cumulative mileage since I started the car up is up to almost 45 MPG now. Going to replace the O-ring tomorrow, hoping that fixes it. Otherwise it's probably time for a new timing chain and new guides (since the timing chain is on correctly).
     
  20. Mr. F

    Mr. F Active Member

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    I don't think it is possible to verify that the chain is on correctly without removing the timing chain cover. Yes, the orange links may be on the timing marks on the camshaft sprockets when the harmonic balancer is at the 0° mark, but the yellow link may be still be off by a tooth.

    Also, you can actually measure the chain stretch to see if it still within spec; that way you don't throw away a perfectly good chain.
     
    bdc101 likes this.