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Engine swap question

Discussion in 'Gen 3 Prius Technical Discussion' started by cnc97, Jun 29, 2018.

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  1. ChapmanF

    ChapmanF Senior Member

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    Did I understand right that the main reason it won't directly go in has to do with the coolant hose fittings pressed into the head being shaped differently and in the way of the EGR?

    Are the locations they press into the same, or is that also different from the old to new head?

    And the Gen 4 valve cover doesn't have the support clips in the right places for the Gen 3 decorative cover?

    -Chap
     
    #121 ChapmanF, Jul 19, 2018
  2. cnc97

    cnc97 Senior Member

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    The water outlet is a bolt on for the Gen 4 and points forward. The Gen 3 is pressed in and points straight to drivers side wheel. It connects to a pipe that goes to the lower hose. The cam bridge( top portion of head just below the valve cover) casting provision for a stud is in the wrong place for the Gen 3 EGR cooler stud.

    Those are the major differences that won’t allow it to be a direct fit.
     
    #122 cnc97, Jul 19, 2018
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  3. cnc97

    cnc97 Senior Member

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    Everything is all clean for reassembly. I have my head cleaned and reassembled with the valves and springs from the purchased engine. The intake manifold and EGR cooler were very dirty. I got very aggressive with cleaner on the EGR cooler. Acid wheel cleaner followed up with an oxyclean soak.
    The intake I soaked in oxyclean for a bit and scrubbed the ports the best I could with a brass toothbrush. Hard enough to get the majority of the deposits without scratching the plastic.

    I can easily see thru the EGR cooler and the intake is almost clean enough to eat out of. Two days off in a row and I feel I accomplished a lot. Head bolts and a couple miscellaneous gaskets NOT offered in the set are due at the dealer tomorrow. Maybe I get two more days off in a row this coming week and get it done.
     
    #123 cnc97, Jul 19, 2018
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  4. ASRDogman

    ASRDogman Senior Member

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    The Gen4 head design is different, obviously, but is the block the same? Not sure if I understood what you were writing.
    If they would have included the EGR system, do you think it would have been a straight switch with the Gen3?
    Did you seat the valves in the head?
     
    #124 ASRDogman, Jul 20, 2018
  5. mjoo

    mjoo Senior Member

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    Gen 3 (2010_cyl_head.jpg) versus Gen 4 (2016_cyl_head.jpg). Notice the mounting studs for the EGR assembly are in different spots.
     

    Attached Files:

    #125 mjoo, Jul 20, 2018
  6. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    There's several interfaces between the EGR system and adjacent components. If I'm understanding correctly, @cnc97 is reusing the (3rd gen) intake and exhaust mainifolds, just the engine is swapped?

    In that case I'd think he's going the safest route using his (3rd gen) EGR cooler/valve/pipe. Everything at both ends of the EGR will fit (obviously*), but there's still the issue of mounting the system securely to the side of the (4th gen) engine, and clearance from that engine, the aforementioned coolant pipe for example. Also, hopefully all the coolant lines connecting to the EGR cooler will still work.

    * This presumes the 4th gen engine when installed, has interfaces for the connection to the intake and exhaust manifolds exactly (shape, location and orientation) per 3rd gen. I think this is the case; if not he'd be in a world of hurt.
     
    #126 Mendel Leisk, Jul 20, 2018
    Last edited: Jul 20, 2018
  7. ASRDogman

    ASRDogman Senior Member

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    Might as well drop the oil pan and clean everything. And the pull the pistons and clean the rings/pistons.
    If you put everything back in the same order you shouldn't have to hone the cylinders.
    Overall, I think it was a good risk for the rewards. And you've gain a lot of experience!
    You'll know what to tell someone who wishes to use a 4th Gen in a 3rd Gen car.
    I have found so far working on a Prius is very easy! I expected cleaning the EGR system would be a royal pain,
    it was actually simple. The original owner said he never drove over 65mph unless he passed someone.
    And it was garaged. He did all the maintenance and had all the paperwork.
     
    #127 ASRDogman, Jul 20, 2018
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  8. mjoo

    mjoo Senior Member

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    Emphasis added:
    So, 3rd gen head, manifolds, EGR on top of 4th gen block. 3rd gen head fixed with 4th gen parts. New head bolts.

    I think that's right, @cnc97 please correct me if it's wrong
     
    #128 mjoo, Jul 20, 2018
    Last edited: Jul 20, 2018
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  9. padroo

    padroo Senior Member

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    So basically he installed a short block.

    11400-37280 - Genuine Toyota BLOCK ASSEMBLY, SHORT

    Next question is if you bought a new short block from Toyota would the oil pan and other parts needed from the old engine bolt up or would it be a nightmare? Would other parts from the old engine fit the new one?
     
    #129 padroo, Jul 20, 2018
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  10. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    3rd gen head is what the EGR connects to, still there's something fouling the EGR valve/cooler, coolant spigot on the 4th gen block.
     
    #130 Mendel Leisk, Jul 20, 2018
    Last edited: Jul 20, 2018
  11. padroo

    padroo Senior Member

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    If someone were into casting aluminum an adapter could be made that you could unbolt the Gen 4 water inlet and make the new one like Gen 3 and just bolt it onto the Gen 4 head.
     
    #131 padroo, Jul 20, 2018
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  12. cnc97

    cnc97 Senior Member

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    It would need to come straight out. Have 3/8 fitting pointing forward, and a 5/8 fitting pointing straight out as well.

    Plus and adapter plate fashioned out of the Gen 4 EGR cooler to bolt the Gen 3 cooler too. LoL
     
    #132 cnc97, Jul 20, 2018
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  13. cnc97

    cnc97 Senior Member

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    You got it. Just the Gen 3 head castings.
     
    #133 cnc97, Jul 20, 2018
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  14. padroo

    padroo Senior Member

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    Are the flywheel's the same?
     
    #134 padroo, Jul 20, 2018
  15. cnc97

    cnc97 Senior Member

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    Flywheel and damper are different. But they interchange between crankshafts.
     
    #135 cnc97, Jul 20, 2018
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  16. cnc97

    cnc97 Senior Member

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    The amazing thing to me is how little resistance to turning there is on the crankshaft of the Gen 4 block. This car is going to drive so much differently then I was used to.
     
    #136 cnc97, Jul 20, 2018
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  17. cnc97

    cnc97 Senior Member

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    The bolts holding the cam bridge to the head have finally arrived. They were on back order. I had the thread pitch and length, so I checked about getting them from a nut and bolt store here, and they were almost double the price. So tomorrow I should get the head, cams, and timing chain back on it. If I get time, I may stab it back into the car.
    I also had to locate the oring seal for under the valve cover for the VVT solenoid. So it’s been a few days of no progress. Hopefully it’s back to driving the end of the week.
     
    #137 cnc97, Jul 25, 2018
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  18. ASRDogman

    ASRDogman Senior Member

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    mmm, seems you should have more resistance because it's newer.
    I do hope you get it running for the weekend! And that everything works as it's designed to work!
     
    #138 ASRDogman, Jul 25, 2018
  19. VintageGold

    VintageGold Junior Member

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    I've been hunting for a lower mileage Gen3 engine and recently found a Gen4 with only 41k miles which was priced better than the Gen3s I've been looking at. I know they both use the same 2ZR-FXE engine but between the Gen3 and Gen4, there would be differences. I came across this thread and read through it hopeful that the Gen4 engine would work.

    Assuming I had access to all the parts from a Gen4 Prius (water pump, EGR cooler, intake manifold, exhaust manifold, etc.), what would I need for the best possible outcome to swap the engine into a Gen3...with the least amount of modification?
     
    #139 VintageGold, Jul 26, 2018
  20. padroo

    padroo Senior Member

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    The big thing looks like the head. He is using his Gen3 head. It looks like it has mostly to do with the water connections on the drivers side of the engine. I'm sure he will chime in when he sees this.

    It would be nice if we could get someone like Doreman to make a part to make everything hook up.
     
    #140 padroo, Jul 26, 2018
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