Death Rattle... clean manifold & EGR, new plugs, no change

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Nor'easter, Oct 13, 2021.

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  1. ChapmanF

    ChapmanF Senior Member

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    Rattling is caused by misfiring. Misfiring is caused by lots of things.

    There are some posters who will give more or less confident narrower opinions on the cause based on exactly when your rattling comes and goes. That's one available clue. There are some tests that can identify whether the oft-suspected head gasket is the cause.

    Other than that, it's a matter of misfire diagnosis, which is a big topic, with other posts giving more ideas already. Here's one.
     
    #101 ChapmanF, Jan 30, 2022
  2. Nor'easter

    Nor'easter Member

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    #102 Nor'easter, Feb 9, 2022
  3. ChapmanF

    ChapmanF Senior Member

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    Those look like pictures of a transmission damper whose coil springs have all been pounded to smithereens (lying in the bellhousing in the lower picture).

    Once that has happened, the car will make clatters and rattles just because the damper's got no springs.

    Something else was the original cause of the clatter that pounded the springs.
     
    #103 ChapmanF, Feb 9, 2022
  4. Nor'easter

    Nor'easter Member

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    I think Aisin used crappy springs that lost their preload over time. And indeed, the rubble you see is the remains of the springs, seasoned with bits of cast aluminum from the transmission housing, lubricated with ATF from where the trans housing wore through. I'm hopeful that the updated part I bought from Japan has better springs.
     
    #104 Nor'easter, Feb 9, 2022
  5. ChapmanF

    ChapmanF Senior Member

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    I would be pretty surprised ... that aspect of how the Prius 'damper' is built is shared with pretty much every manual transmission clutch disc ever, kind of a mature product space.

    I see the mileage was 121k at the start of this thread. One really just doesn't hear of clutch discs turning their springs into rubble over 121k miles for no reason. Could it happen? Well ... never say never.

    By the same token, the Prius powertrain does have the feature that any misfiring for any reason, possibly even just in some earlier period of the car's life, works those springs like crazy.
     
    #105 ChapmanF, Feb 9, 2022
  6. Nor'easter

    Nor'easter Member

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    The Prius bumps starts it's engine... every single time. That right there is a lot of wear and tear on the torsion damper.
     
    #106 Nor'easter, Feb 10, 2022
  7. ChapmanF

    ChapmanF Senior Member

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    And yet the number of Prii that pass 121,000 miles without having pounded their springs into confetti seems rather large.

    The "bump" comes from MG1, which can be spun with any amount of torque the ECU chooses to apply.
     
    #107 ChapmanF, Feb 10, 2022
  8. Mendel Leisk

    Mendel Leisk Senior Member

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    Give it time, make sure the cold start shakes are gone. The damper plate failure "may" have been a consequence of head gasket allowing uncompressible coolant into a combustion chamber. You've remedied the damper, but keep an eye on it. Leak-down test?
     
    #108 Mendel Leisk, Feb 10, 2022
  9. ChapmanF

    ChapmanF Senior Member

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    It was near-certainly a consequence of something causing uneven engine rotation over some period of time; a head gasket issue would be one of the many candidate somethings.
     
    #109 ChapmanF, Feb 10, 2022
    Last edited: Feb 10, 2022
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  10. Nor'easter

    Nor'easter Member

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    Car never had any cold start shakes, never set any codes, leak down numbers were 100/98 ish, borescopic inspection was fine, plugs were perfect, the EGR was cleaned out end to end and found to be dirty at 120K (of course) but without obstruction. Consumes neither coolant nor oil (synthetic since new). It's always returned 48 - 60 mpg. The only "roughness" we've experienced with the engine was after the damper had obviously loosened up and was rattling like crazy, but only under certain light load conditions, e.g. climbing a shallow grade at 20 mph. It -always- ran great at full throttle, and it -always- ran smooth at no load.


    I agree that there's no excuse for such a failure. It's literal 100 year old technology. But out in the real world, the first two pros that looked at the car ID'd "failed transmission input damper" immediately, neither suspected misfiring, both had seen this failure before. And the original 2010 part is obsolete, superceded by a later part #. You can find videos on Youtube that show loose and busted dampers. It happens.

    Anyhow, I expect the car to run like a top now. We pick up tomorrow morning.
     
    #110 Nor'easter, Feb 10, 2022
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