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Gen4 to Gen3 engine swap using gen 4 intake and egr, DONE!

Discussion in 'Gen 3 Prius Technical Discussion' started by Dave Hanson, Aug 13, 2019.

  1. Dave Hanson

    Dave Hanson Member

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    I would too, but $450 is to much, for an experiment. Did find the headpipe and catalytic converter on eBay for just over $100, so may go that route.
     
  2. DaYooper

    DaYooper Member

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    image.jpg
    I have the intake, the EGR cooler and valve assembly, but not the exhaust manifold. How did you use the old throttle body? The wires are too short to flip it 180 degrees?
     
  3. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Here's a screen grab from @NutzAboutBolts video, his coolant hose revisions. It's an "extra" video, on his YouTube channel:

    upload_2019-9-1_9-51-13.png



    In the video's linked at Priuschat, he gets into coolant hose rework on video #13 IIRC.

    Addendum: I've attached a pdf with both @Ragingfit and @Dave Hanson 's sketches (with acknowledgements).
     

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    #23 Mendel Leisk, Sep 1, 2019
    Last edited: Sep 1, 2019
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  4. Dave Hanson

    Dave Hanson Member

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    When I changed to the gen4 wire looms I found enough extra wire.
     
  5. DaYooper

    DaYooper Member

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    Ah. Didn't catch that part. Did you have to use the Gen 4 dipstick too? Looks like the Gen 3 is in the way.
     
  6. Dave Hanson

    Dave Hanson Member

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    Yes, I used the gen4 dipstick, had to bend it back slightly to clear the gen3 air horn. Didn't try the gen3 dipstick.
     
  7. DaYooper

    DaYooper Member

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    Getting there.
     

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  8. DaYooper

    DaYooper Member

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    End of day one.

    1. Pipe bent
    2. Intake installed and throttle body wire fixed.
    3. EGR bolted in

    To do:

    1. Find a place for MAP sensor.
    2. Route the plumbing.
    3. Through it all back together
     
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  9. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Is that a gen 3 intake manifold?

    If it was gen 4 intake manifold, with gen 4 engine, and gen 4 EGR, I can't see how there'd be a fit problem, between the EGR tube and intake manifold.
     
  10. DaYooper

    DaYooper Member

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    It's the same as the OP. Gen 3 exhaust manifold with Gen 4 EGR system. Gen 4 intake system except for throttle body. Gen 3 air horn.

    One thing I have learned is that the MAP sensor is in a different place on Gen 4 intake. I am going to try to relocate using rubber hose from the Gen 4 MAP sensor location to the Gen 3 location.
     
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  11. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    It looks like a fit problem, between the EGR pipe and the intake manifold. Maybe because the EGR valve/cooler is so far NOT bolted to the cylinder head?

    I had pictured, that the way to do that exhaust manifold pipe bend, was to solidly bolt the EGR valve/cooler to (4th gen) cylinder head, also solidly bolt the (3rd gen) exhaust manifold on, and then start the heating/bending/twisting, to bring the exhaust manifold pipe to where it needs to be.

    @Dave Hanson recommends to do all this before engine install. Besides the obvious benefit of not using torches in the engine bay, having the EGR system attached to the cylinder head before putting the engine in eliminates a real PIA chore.

    I think you could even pre-install the exhaust manifold, with EGR connection pipe bent and bolted to the cooler: there's just enough room to miss the windshield when subsequently installing engine. But maybe too risky??
     
    #31 Mendel Leisk, Sep 2, 2019
    Last edited: Sep 2, 2019
  12. DaYooper

    DaYooper Member

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    Yes engine install was 6 months ago with Gen 3 EGR. Still had problems with the Gen 3 EGR system. When this thread came about, I was hopeful to use the Gen 4 system that came with the new engine. So retrofitting was the main option. I wasn't going to pull the engine again. Just getting down to the plumbing now will post results.
     
  13. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Ok.

    One question first, and I think I know the answer:

    If you have a 4th gen complete engine (including intake manifold), all except 3rd gen exhaust manifold, and install the 4th gen EGR valve/cooler assembly, just solidly bolt it to the cylinder head connection points: there is a gap between the EGR cooler flange and the exhaust manifold pipe it should connect to, correct? It's not an interference, it's a gap?

    If that's the case, I would do that: install the EGR valve cooler to the head (not the exhaust pipe connection), then start heating/bending the exhaust pipe that's supposed to connect, bring it over to the EGR cooler flange, and then further heat/rotate to get the flange holes aligned.

    There are maybe close to 10 connecting bolt/nuts/studs involved, and the only odd-man-out is that exhaust manifold connection; it's the only thing "3rd gen". Everything else is 4th gen, and fits, by design. So it would seem to me it's best to make all those connections first, and finally fix the exhaust manifold pipe, bring it inline with the rest.
     
    #33 Mendel Leisk, Sep 2, 2019
    Last edited: Sep 2, 2019
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  14. Dave Hanson

    Dave Hanson Member

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    Actually, this is the way I did it. The cooler gives you more leverage to get it just right. Bolt everything up loosely, heat it up again and tighten all the bolts up to get it in the final position. I also got rid of the studs, so the cooler can come out easier down the road for service. Sounds like DaYooper has gotten the final bending done and is just trying to get the last few steps done for the conversion.
     
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  15. DaYooper

    DaYooper Member

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    Dave. Do you know if the EGR wires are switched On the Gen 3 loom as well?
     
  16. Dave Hanson

    Dave Hanson Member

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    My post#7 on this thread covers that. Red and purple wires are swapped. Post # 14 covers this and the MAP sensor wiring changes.
     
  17. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Yeah I had lingering doubts as I typed my (100% armchair mechanic) instruction, lol.
     
  18. cnc97

    cnc97 Senior Member

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    Every one of these threads I read makes me wonder what if I had NOT done my swap. Would we be at the point we are with them now or no? It’s just crazy when I look back 15 months ago, I was told “No, it can’t be done”. Then John Kelly (Weber Auto) chimed in when I asked him what he thought.

    I too wish I could be in the service department when a tech raises the hood on a Gen 3 with a Gen 4 engine under the hood. That would be something to see.
     
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  19. cnc97

    cnc97 Senior Member

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    And by the way, 15k miles later it still hasn’t used any oil or lost any coolant. The oil pressure switch seeps just enough oil to get a wet appearance, but I’m not going to mess with it.
     
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  20. michaud85

    michaud85 Member

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    I have gen 4 throttle body... Can i use it?

    Im half way through the install today. New motor is prepped and ready to drop in I just have to practice depinning these things so i can swap sensor pins and harness heads.

    Thank you so much for this coolant diagram.

    Im going to try to drop this thing in fully rigged up with only the water pump removed, this way I can save the intake manifold gasket but i do have a new one incase. I might take the throttle body off to. At least this time if i cant get the clearance to drop it in i can just pull it out and easily remove stuff.
     
    #40 michaud85, Feb 1, 2020
    Last edited: Feb 1, 2020