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173k, head gasket time, darn it.

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by taupehat, Jun 13, 2021.

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  1. The Critic

    The Critic Resident Critic

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    Even Clamping force is critical for the longevity of the head gasket. The HF Quinn digital torque wrenches with angle are surprisingly good for the money. $169 for 1/2” one, iirc.

    Head bolts only. Ballpark isn’t accurate enough, I would encourage the OP to buy the HF digital torque wrench or one of those brownline torque angle gauges.

    Example of my angle torque wrench in action (attached).

    Also, I might be local to the OP. Maybe I can pop over and help him torque the head bolts?
     

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  2. taupehat

    taupehat Junior Member

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    I'm in Sonoma County. Right now I'm still tearing the motor down and need to measure piston depth before I even bother buying gaskets to torque down. If it comes to that I might take you up on the offer though.
     
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  3. Mendel Leisk

    Mendel Leisk Senior Member

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    The attached Toyota TSB has part no’s for gasket kit and head bolts. The kit contains Toyota head gasket and more or less every other gasket, O-ring and seal. Head bolts, while not strictly necessary to replace, IF they’re still within spec (see my previous post #8 link; one has bolt inspection specs), using new bolts may be prudent course.
     

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  4. wheezyglider

    wheezyglider Active Member

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    Perusing Amazon today I noticed that they seem to be selling the CTA Tools head bolt wrench for the Prius(*) in a standalone listed as: "CTA Tools 9292 Head Bolt Wrench, 10mm - Compatible with Toyota" (It's ASIN B00U1N20RC if you don't like forum-munged links.)

    I know that previously PCers had recommended CTA Tools 9295, which is a set with both 10mm and 8mm. In a reasonable world this solo unit should be a cheaper option (and at the moment it is on sale for $6.82).

    * Since the listing is a couple years old I'm wondering if I missed some detail that makes the 9292 not suitable for the 2ZR?
     
  5. Mendel Leisk

    Mendel Leisk Senior Member

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    “10 mm bi-hexagon wrench” is Toyota’s description. It is slightly different than the 12 mm triple square Gasket Masters advocate. See first link in my post #8, then attachment #5 in that link. In that thread I believe I also post acad sketches of the two, showing the diff. The angle of the points is diff, 60 degrees vs 90.

    8C465470-F6F1-44B7-9C39-0E28F9105216.jpeg
     
  6. wheezyglider

    wheezyglider Active Member

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    Thanks Mendel, I vividly recall that cad sketch -- it left an impression. I was able to find something on the CTA Tools website that confirms that the 9292 is indeed the same 10mm "double hex" that they include in their 9295 item.

    So we can safely consider it an option for recommendation. :)

    upload_2021-6-18_9-53-1.png
     
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  7. taupehat

    taupehat Junior Member

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    Had to take a couple days off from working on the issue due to a heat wave, but got back at it today and I'm this far along - feel like this was the hard part. Now I just need to get the EGR cooler out, camshaft assembly, exhaust manifold, then the head.

    Top of the motor looks great for the age, no gunk depositing anywhere and the camshafts are in perfect condition, completely unworn. Crossing my fingers about the rods though - won't know until the head comes off.
    [​IMG]
     
  8. ASRDogman

    ASRDogman Senior Member

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    ??"Crossing my fingers about the rods though - won't know until the head comes off."??
    Pull the plugs, if they aren't already out. Put 2 of the pistons at tdc. Place a dowl, or screw driver,
    or any "stick" on the top of the piston and place a mark where the top of the spark plug tube is.
    Remove it and place it in the other spark plug hole of the other piston that's at tdc. The mark
    should be in the same place.
    Remove the "tool", rotate the engine so the other 2 pistons are at tdc, and check the other two.
    If all for are exactly the same, no bent rod. If one or more are different, bent rod(s).
     
  9. Mendel Leisk

    Mendel Leisk Senior Member

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    Try to minimize variables as much as possible too: ensure the dowel is consistently perp to cylinder, maybe by pressing against spark plug hole wall. Ensure you’re as TDC as possible. Mark the dowel with maybe a razor blade, on flat atop the spark plug well
     
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  10. taupehat

    taupehat Junior Member

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    You all don't think I'm going to have a problem now that the timing chain is off?
     
  11. Mendel Leisk

    Mendel Leisk Senior Member

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    Rotating the crankshaft and pistons? Or you're concerned to get it out of synch? I think if the chains put back on all the marks, crankshaft and cam sprockets, especially if you did Gasket Master's lock-the-camshafts trick (with shop towel bits on the camshaft races), there's no problem.
     
    #31 Mendel Leisk, Jun 21, 2021
    Last edited: Jun 21, 2021
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  12. taupehat

    taupehat Junior Member

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    Cool. I did the camshaft lock trick so maybe I'll take that approach.
     
  13. Mendel Leisk

    Mendel Leisk Senior Member

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    I should caution: I'm a complete greenhorn in such matters, but that's never stopped me. Just don't come gunning for me if the valves turn into a orchestral percussion section. :ROFLMAO:

    I'd be inclined to rotate the engine by hand, after assembly and before starting it up, with the plugs out to make it easier. Just to verify nothing's colliding.
     
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  14. ASRDogman

    ASRDogman Senior Member

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    You can't bend any valves by turning it by hand, or hand wrench....
    I had thought about the timing chain shortly after I posted, but was off doing other things.
    You'll need to install it or one of the pistons will most likely press against a valve and you won't be able
    to rotate the crank.
     
  15. Mendel Leisk

    Mendel Leisk Senior Member

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    Or lift off the cam shafts first, then all valves will be closed?
     
  16. ASRDogman

    ASRDogman Senior Member

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    If reusing the head, might as well remove the camshafts, and replace the valve guide seals.
    And might as well remove the head, have it checked and make sure it is not warped.
    Then you can rotate the engine without worry, and SEE if any rod is bent...

     
  17. Dilbone

    Dilbone Member

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    I have been told otherwise in terms of being able to bend valves by hand cranking a motor. I have never done it because I don't crank a motor without a timing chain on it; however, I would not be willing to test the theory of whether you can or can't bend a valve while hand cranking with a wrench.

    If you locked the cams down with paper towels and the chain is off then I would absolutely NOT hand crank that motor. Just get the head pulled off and measure them.

    The pistons don't have to be at TDC to measure them...you could just as well measure them at any position since you're just comparing them to each other using the dowel method. Go ahead and measure them with the dowel method if you can't wait until the head comes off to find out.

    SM-G981V ?
     
  18. ASRDogman

    ASRDogman Senior Member

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    I imagine if you tried hard enough and were strong enough and bounce hard enough on the
    wrench, you might be able to bend the valve, but more likely crack the piston.
     
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  19. taupehat

    taupehat Junior Member

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    I've damn near got the head off now. I'll just measure depth once I'm done.
     
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  20. Mendel Leisk

    Mendel Leisk Senior Member

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    That’s a beautiful picture up the page, btw. (y)