1. Attachments are working again! Check out this thread for more details and to report any other bugs.

2010 Head Gasket replacement - questions before reassembly

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

  1. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    22,782
    14,807
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    With the timing chain cover in place, if you slip the harmonic balancer/"pulley" off the crankshaft (after lining it up at 0°) and just peek in past the oil seal, you can manage to just barely see when the yellow link is aligned with the mark.

    [​IMG]
     
    #81 ChapmanF, Nov 28, 2023
    Last edited by a moderator: Nov 30, 2023
    Mr. F, Mendel Leisk and bdc101 like this.
  2. bdc101

    bdc101 Member

    Joined:
    Sep 23, 2023
    249
    85
    0
    Location:
    usa
    Vehicle:
    2010 Prius
    Model:
    ----USA----
    Was able to find time to replace the O-ring tonight... reset code but the P0016 was immediately present as a "pending" code after I started it up again.

    Mr. F, I have been wondering that, and it seems to me that what you're saying could possibly be true. Highly unlikely but possibly true. I was hoping not to take the timing cover off again, since I have to drain the coolant, but I guess I gotta do what I gotta do. A new chain and the lower guides is $311 plus shipping from Lithia. Won't be the end of the world. I'm sure I can find the procedure to measure chain stretch in Mendel's signature but if you happen to know where it is, let me know :p
     
  3. Mendel Leisk

    Mendel Leisk Patron saint of newly poured sidewalks

    Joined:
    Oct 17, 2010
    54,125
    37,923
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Last link in signature is full engine section.
     
    bdc101 likes this.
  4. bdc101

    bdc101 Member

    Joined:
    Sep 23, 2023
    249
    85
    0
    Location:
    usa
    Vehicle:
    2010 Prius
    Model:
    ----USA----
    Yeah, I checked and it's not in there unfortunately
     
    Mendel Leisk likes this.
  5. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    7,379
    4,311
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
  6. bdc101

    bdc101 Member

    Joined:
    Sep 23, 2023
    249
    85
    0
    Location:
    usa
    Vehicle:
    2010 Prius
    Model:
    ----USA----
  7. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    7,379
    4,311
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    It is part of the repair manual
     
  8. ASRDogman

    ASRDogman Senior Member

    Joined:
    May 29, 2018
    5,715
    3,075
    0
    Location:
    Florida
    Vehicle:
    2010 Prius
    Model:
    Two
    If it is just one tooth off on the crankshaft, and you align the crank at zero,
    both cam sprockets will be off. The chain colored marks can line up correctly
    on the sprockets, but they won't be positioned in the correct spot And the engine will
    not run smoothly. One or more of either intake or exhaust valve will likely be open
    slightly cause burn fuel/air to escape thus no having the full pressure to push the
    piston down. If the engine ran at all, it will be weak.

    Since his engine is smooth, with power, there is a 99.999999% chance the timing
    chain is correctly in place.

    Since the crank pully wll only fit one way, it's impossible to install it on the crank, without
    forcing it and damaging it and the crank shaft.
    If the chain was installed with the colored mark one tooth off, and the marks on the cams
    where installed one tooth off, to the left or right, as long as all 3 are equal to the left or right,
    the engine will run normally.

     
  9. bdc101

    bdc101 Member

    Joined:
    Sep 23, 2023
    249
    85
    0
    Location:
    usa
    Vehicle:
    2010 Prius
    Model:
    ----USA----
    Where does one go to find the repair manual -- is it what you have to pay the subscription to Toyota for? I was unable to find it by searching but I didn't pay the subscription to Toyota to look there either.
     
  10. Mendel Leisk

    Mendel Leisk Patron saint of newly poured sidewalks

    Joined:
    Oct 17, 2010
    54,125
    37,923
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    I checked, using search string based on @rjparker's posting; it is in the Repair Manual engine excerpt pdf (linked at bottom of my signature), commence on page 159. Title is "INSPECT CHAIN SUB-ASSEMBLY".

    For "Pull the chain with a force of 147 N (15 kgf, 33.0 lbf)", I'd be inclined to suspend the chain, connect a few dumbells to the bottom, take a measurement, reduce/increase the weight at the bottom, see if if makes an appreciable difference. If not, you're measurement is likely accurate.
     
    #90 Mendel Leisk, Nov 29, 2023
    Last edited: Nov 29, 2023
    bdc101 likes this.
  11. Mendel Leisk

    Mendel Leisk Patron saint of newly poured sidewalks

    Joined:
    Oct 17, 2010
    54,125
    37,923
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    I found the Repair Manual sketch a little vague, crunched this. It's basically the inside-to-inside distance from left-side pin in link one, to right-side pin in link eight:

    upload_2023-11-29_7-58-48.png
     

    Attached Files:

  12. bdc101

    bdc101 Member

    Joined:
    Sep 23, 2023
    249
    85
    0
    Location:
    usa
    Vehicle:
    2010 Prius
    Model:
    ----USA----
    Ok! So today I put the car in the air again and pulled the valve cover and crank pulley. I checked timing again and it was off a tooth on the crank pulley! I hadnt realized you could see the yellow link when the crank pulley was off. I had simply put the crank pulley to TDC and then checked the top two painted links. And it turns out, you CAN indeed have the bottom link off a tooth while at TDC and having the painted links in the correct positions on the cam sprockets. This is because without any marks on the head to line the cam sprocket marks up against (per our long and drawn out discussion), the painted links might be in the right place on the sprockets, while the crank is at TDC, but it doesn't mean the cam sprockets are in the right place. Verification of the painted link on the crank sprocket must also be made in order to time the engine correctly.

    So - After this discovery, I unfortunately learned that there is enough room to move the chain one link on the exhaust cam sprocket, but not on the intake cam sprocket (and you certainly can't move it on the crank sprocket with the timing cover on). So I had to take the timing cover off again, drain the coolant, and lost about a quart of oil when taking the timing cover off too. Added a couple hours of work. But when I got it back together, no codes! And no pending codes either! (It had always had the P0016 as pending as soon as I reset it, previously.) I havent driven it yet but got it all buttoned up, with the wipers back on and ready to drive in the AM.

    I am super happy I didn't need to buy a new timing chain. At least not yet. It's possible that I installed it wrong, or it's also possible that it skipped a tooth because it is worn out and if it's the latter, it would probably happen again. I'll find out shortly I suppose.

    Looking forward to driving this baby a lot this week! And now I can move into my next project, a homemade battery reconditioner!
     
    #92 bdc101, Dec 3, 2023
    Last edited: Dec 3, 2023
    Mendel Leisk likes this.
  13. ASRDogman

    ASRDogman Senior Member

    Joined:
    May 29, 2018
    5,715
    3,075
    0
    Location:
    Florida
    Vehicle:
    2010 Prius
    Model:
    Two
    Either cam sprocket can be off a tooth with the other two marks on, and also with the crank.
    Unfortunetly, you were off a tooth when you installed it. It does happen, other have done it too.
    The chain CAN be installed on each sprocket correctly without the marks on the chain,
    but it's tremendously easier WITH the marks on the chain! (y)

    But you should ALWAYS rotate the crank 720 degrees after releasing the tensioner to make
    sure it's still correct and had not jumped a tooth somewhere.

    There is tension from the crank to the intake cam and between the exhaust cam, but it's loose
    between the exhaust and crank sprockets until the tensioner engages, when you rotat the crank
    counter clockwise that little bit, which might cause slack between the crank and intake cam.

    "IF" the chain was worn, there would be a LOT of play so that you could move either cam back and
    forth and chain would not move, like on bicycle sprockets.

    Bottom line, you can the chain on correctly now, and no more codes!!

    I am very happy for you! (y)(y)(y)

     
    bdc101 likes this.
  14. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    22,782
    14,807
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    This sounds to me like a challenge.

    Sadly, I don't have any other reason right now to go out and mess with my timing chain, and don't really want to do it just for a challenge, but I'd love to see a video of someone else taking it up.

    I'm assuming you had the tensioner plunger removed?
     
  15. bdc101

    bdc101 Member

    Joined:
    Sep 23, 2023
    249
    85
    0
    Location:
    usa
    Vehicle:
    2010 Prius
    Model:
    ----USA----
    Yes, I removed the tensioner and then I even loosened the exhaust cam sprocket bolt, to get even more clearance. I worked at this for almost an hour before I gave up. I don't believe there is physically enough clearance between the intake cam sprocket and the timing cover to move the chain, even if you had it completely slack.
     
  16. bdc101

    bdc101 Member

    Joined:
    Sep 23, 2023
    249
    85
    0
    Location:
    usa
    Vehicle:
    2010 Prius
    Model:
    ----USA----
    Just drove it around town for a bit, no codes, and it drives super smooth. It's definitely a little bit quieter. If I had driven a Prius for more than 10 minutes before I started it back up, I would have been able to tell, but I thought it was just a raspy motor. A bit quieter now!
     
  17. bdc101

    bdc101 Member

    Joined:
    Sep 23, 2023
    249
    85
    0
    Location:
    usa
    Vehicle:
    2010 Prius
    Model:
    ----USA----
    Report after two weeks of driving: car runs great! Battery seems to hold a pretty good charge (Dr Prius says 59%), mileage on first 200 miles was 42.5, and this tank is looking more like 44 so far. The car drives really smooth, for something that has 263k miles now, it feels like a much newer car. No more check engine lights after I got the timing on straight. It's also quite fast for such an economical car. I'm really happy driving it and my kids like it too.

    I need to repair the paint on the roof, because it has cracked pretty bad and if I didn't live in the desert it would probably be very rusty. And I am trying to fix the CD player, which won't load any CDs. But the nav and backup camera work great. And I am also collecting parts to build a homemade battery reconditioner.
     
    CR94 and ASRDogman like this.