gen 4 engine to gen 3. engine swap. Best practices, parts, etc?

Discussion in 'Gen 3 Prius Technical Discussion' started by Buyguy, Mar 8, 2021.

  1. Buyguy

    Buyguy New Member

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    Hey guys,
    I have a Gen 3 2011 Prius.
    I was losing coolant and couldn't find any leak. MPG loss so I changed the head gasket.

    I ran it about 1 mile and died, when it does start again it's blowing a crazy amount of sweet-smelling vapor out the exhaust. So I either screwed up the gasket (I would like to think this is not the case) or the block has a crack I couldn't see.

    I want to swap out the engine. Obviously, I have been looking at the cheaper gen 4. I also like the potential for fewer engine issues in the future.

    So its either
    JDM gen 3 for $1200 ~65K miles

    Local USA gen 4 for $600 ~50k miles


    Assuming I swap to gen 4 2ZRFXE

    Is there any difference between
    gasoline, 1.8L (2ZRFXE engine), Prius (VIN FU, 7th and 8th digit), VIN A (5th digit)
    gasoline, 1.8L (2ZRFXE engine), Prius (VIN FU, 7th and 8th digit), VIN B (5th digit)
    gasoline, 1.8L (2ZRFXE engine), Prius V (VIN EU, 7th and 8th digit), (VIN N, 5th digit)

    These are options when I go to buy on car-part. as long as I have a 2ZRFXE I'm ok?


    A lot of people here have been talking about using the Gen 4 intake manifold on the swap and having to modify it. This guy here says he used the gen 3 intake manifold and didn't modify anything.



    Combinations they used.
    Gen4
    Engine
    EGR
    Water pump

    Gen3
    exhaust manifold
    Flywheel assembly
    intake manifold
    o2 sensor
    wiring hardness
    Fuel rail/injectors


    They made it seem pretty easy.
    Thoughts? I want to attempt this coming week


    edit:
    and this guy uses the gen3 egr and intake
     
  2. ASRDogman

    ASRDogman Senior Member

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    It would have been nice if they showed HOW they did the modifications.
    The ground wire to the motor mount does nothing, except ground it to the head. They could
    have just connected it to the same place on the head. The motor mount does not have a
    metal to metal contact, it rubber.
     
  3. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    Was the coolant loss a lot more than before the head gasket change? If so I’d suspect the HG.

    1. What brand HG?
    2. Did you follow correct head bolt torque procedure?
    3. When placing the head back on, did you drag it laterally?
    4. Are you able to read codes, and do you have any, before and/or after HG replacement?
    5. Maybe not directly tied in but: did you clean the Exhaust Gas Recirculation and intake manifold?
     
  4. ASRDogman

    ASRDogman Senior Member

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    hhmmmmm I'm wondering if the torque for the head bolts would be different if using a Gen3
    head on the Gen4 block???
    If the procedure for the Gen4 is the same as the Gen3, and the installation is the same for both,
    and the torque measurments are the same, I guess they would be the same.
     
  5. Buyguy

    Buyguy New Member

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    Agree with what you said.
    I'm not sure what you mean by not having a "metal to metal" contact. I attaches to the block and the chassis via metal to metal.
     
  6. Buyguy

    Buyguy New Member

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    1. HS26515PT1 (HS26515PT-1) Felpro.
    2. yes i did it all correct
    3. hmm no. i was very careful
    4. yea. not throwing any codes ill try again in a bit here. besides the generic "engine not starting" code.. i thnk its p03xxx
    5. yes cleaned it
     
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  7. ASRDogman

    ASRDogman Senior Member

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    He put one ground wire on the motor mount, that attaches to the block.
    It doesn't ground to the chassis because the mount is rubber to absorb the vibration.
    He should have just attached the wires to the head like the other ground wires.
    He thinks the is a chassis ground, it is not.

     
  8. Buyguy

    Buyguy New Member

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    ahh yes. ok i agree with that..
    Im thinking of going JDM. it will just be easier for me. if I can save 5 hours of work then its worth a few hundred dlrs.
     
  9. Prii_Ownr

    Prii_Ownr New Member

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    Is it not possible to swap the entire 4th gen engine/exhaust assembly (engine, intake manifold, exhaust manifold, and entire exhaust all the way back to the end of muffler) into the 3rd gen and only be required to modify the wiring? Yes, the 3rd gen flywheel assembly will be required but this would be a quick swap (no mods required).
     
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