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Know gen4 to gen3 engine migration issues

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Su Mo, Mar 20, 2023.

  1. Su Mo

    Su Mo Junior Member

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    Can you please post known inconsistencies/incompatibilities or issues gen3 runs into with a gen4 engine?

    Just trying to make a decision if it’s worth trying or no.
    Thanks!
     
  2. ChapmanF

    ChapmanF Senior Member

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    A couple that I know of:

    • The EGR systems are different. In Gen 4 it comes from a lower-pressure port on the exhaust manifold, so all of the EGR components are upsized from Gen 3 to continue to flow the right amount. If the Gen 4 EGR components are used in a Gen 3, supplied from the higher-pressure location on the Gen 3 exhaust manifold, the flow will be too much and the engine will run poorly. The best results seem to be with reusing Gen 3 EGR components, though some people have experimented with the Gen 4 components and some kind of improvised restriction to reduce the flow. I don't think I've seen any of those experiments end with complete satisfaction.
    • The cooling system plumbing has differences, and people come up with ways of adapting the plumbing to make things fit, and there are at least two different diagrams floating around for how to do that; one of them is clearly kind of bogus and has assumed flow directions backward, and one looks a little more plausible. People usually don't describe exactly what they've done, and the forums are teeming with reports of these swaps that are plagued by overheating issues afterward. The threads usually end trying to blame it all on something like trapped air or the thermostat jiggle pin, which looks a lot from the sidelines as if there's nobody who knows why yet.
     
  3. PriusCamper

    PriusCamper Senior Member

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    There's a guy from Oklahoma on here who travels around and can do these engine swaps in a day in your driveway for $1500... I'm not sure what his username is on PriusChat? Does anyone know?

    He goes by: @Bubbly-Ad2060 on Reddit's social network.
     
  4. Su Mo

    Su Mo Junior Member

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    I can’t find with @Bubbly-Ad2060 on reddit.
     
  5. PriusCamper

    PriusCamper Senior Member

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    Try commenting on his post... And please ask him how to find him on PriusChat. I used to have that info and now I can't find it!

     
  6. rjparker

    rjparker Tu Humilde Sirviente

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