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Which engine would you pick JDM gen 3 or used or gen 4?

Discussion in 'Gen 3 Prius Technical Discussion' started by daley, Mar 24, 2024.

  1. daley

    daley Junior Member

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    I had the head gasket go on my engine and I am going to be replacing the engine this week. I will rebuild the engine after and keep it around or sell it but I need to get the car back on the road quickly.

    I have found locally a gen 4 engine from a 2017 Prius Prime that has 90k miles on it.
    Apparently it was running but I have no way of testing this. It is sold from a private party so I guess I get what I get with no warranty.

    For $100 more I can get a JDM Gen 3 engine with 90 days warranty and supposed 50k miles on it.

    I would like to do the gen 4 swap but was wondering what folks opinions and choices on here would be.
     
  2. Tombukt2

    Tombukt2 Senior Member

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    Some of the JDM engines when they're pulled or not treated very well they can be stored and wet locations and all kinds of things that he wouldn't really want to hear about and you can see it in some of the engines that get imported lots of rust You can see there's been water around the outside of the engines quite a bit whether they've been sitting in it or what's been going on once they're pulled in Japan they're like scrap literally salvaged so they can be rained on and in wet locations and it's a numbers game so nobody really cares That's one issue with JDM imports and this goes on through front clips and all of it You can just see it when the stuff arrives in the States not much care has been thawed out or given at all so there's always that a Gen 4 engine might be an okay thing they've added some sleeves and changed the rings and some few other things I don't know if we know any of that is really working yet this stuff generally doesn't rear it's ugly head until around 150 K for most it seems like maybe a little more mileage so the Gen 4's en masse. Are just starting to get up in this mileage. It also looks like on the Gen 4 they have drastically reduced the amount of EGR flow or something Just look at the ports that feed the engine.
     
    DieselHammer likes this.
  3. DieselHammer

    DieselHammer Junior Member

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    Neither. I just had this issue and almost fell for the JDM supposedly low mileage low cost pitch. Let’s face it, we all own a Prius because we enjoy getting our bang for our buck. I sure hope my first car is a Prius said no 16 year old kiddo ever! As time moves on we learn to appreciate the value of the dollar bill. I was referred to a shop in the DFW area called Hybrid Car Clinic http://www.hybridcarclinic.com They steered me away from an unknown history engine. They had a Lexus fresh out of the 12 month warranty that was a JDM installed by the local Lexus dealership. Unfortunately, Lexus dealership was not going to help out on the $8400 new engine bill they issued this customer 14 months earlier. The customer was now paying again! Talk about pi$$ poor luck! To earn my business they were willing to put in a JDM for cheap although they weren’t giving me a labor warranty on a JDM motor and JDM only offers a 45 day mechanical warranty. So … after 45 days … maybe pay again?!?! I chose it was worth the extra fee to get it fixed right the first time. They had another car in that had just had the head gasket repaired by an independant shop. There were holes in the side of engine … crazy! I’d only heard of these things. The shop invited me in to see their machining setup and engine rework to new standards. You can learn more talking to these guys regardless if you are close to them or not. Super nice approachable guys and knowledgable. Very fair price and I got a 24 month unlimited mileage warranty too! No one came close to the warranty or the value. I hope this helps.
     
    #3 DieselHammer, Mar 24, 2024
    Last edited: Mar 24, 2024
    Danno5060 likes this.
  4. daley

    daley Junior Member

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    Thanks for the tips guys.

    I have to get the car running this week and budget is limited so I don’t see how rebuild is possible right now.

    I’m leaning towards the Jdm for now and the reason being I will be picking it up in person so can see the engines condition before I buy it, obviously I can’t see inside it but I’ll can see something about it. The seller isn’t that far away from me and offers 90 day warranty on the engine. I’ll be installing it myself so no labor costs other than my time.

    The gen 4 worries me as I don’t really know it’s history, looks like an auction car being parted, I don’t want a major headache if it doesn’t work. I’m also concerned about overheating issues, I haven’t seen any conclusive swap stories that make me feel confident about the coolant set ups when putting in a gen 3.

    I need the car to work for the next 3-6 months so I’m thinking $1200 on the Jdm is worth the gamble. If I get 3 months out of it it’s cheaper than renting a car!
     
  5. Tombukt2

    Tombukt2 Senior Member

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    So the hybrid car clinic is talking 8400 for their machined rebuilt whatever it is two ZZ fxe assembly . Actually that sounds about right and if your generation 3 is worth that to you and what's your standing there looking at then by all means carry on my Gen 3 neither of them I don't see that kind of money any kind of way of course I don't live in California and pay tens of thousands of dollars in basic property tax either or any of that kind of nonsense so yeah I won't see $8,000 in it I don't know 12-year-old car absolutely not of course that's what some of y'all are paying for generation twos with supposed low mileage so you know just what makes you happy hell I don't even think Alexis CT 200h with low mileage on it is worth $8,400 they're selling for 10 and $12,000 but that doesn't mean anything to me what that tells me is about a lot of people don't know what they're doing and it shows because right after not long after they do that they're buying a terrain or a Tahoe. And the Gen 3 and it's clones sitting out in the parking lot looking for the highest bidder to start the process all over again and boy you people just keep coming out of the woodwork to restart the process it's kind of hysterical but hey whatever makes you happy.
     
  6. ASRDogman

    ASRDogman Senior Member

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    If you're low on money, and time. Putting a Gen 4 motor in place of the Gen 3, you'll have
    issues. You'll have to reroute the egr pipes, which requires heating it up, and I think the coolant
    lines have to be modified also...And over heating... From those who've done it, it's a lot of work, and extra money.



     
    #6 ASRDogman, Mar 25, 2024
    Last edited: Mar 25, 2024
  7. Seymour1

    Seymour1 Junior Member

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    I read every post to learn what "JDM" means. Does it mean a car built in Japan? Are they better than American made, or the same?
     
  8. C-in-DC

    C-in-DC Member

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    think it comes down to the condition of the car. Is the interior immaculate or a flower child’s paradise?
     
  9. Eddie25

    Eddie25 Active Member

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    I'd at least take the cylinder head off and measure it. You might get lucky. A gasket slap without a machine shop involved could be done for $250-400 and a days work. I'd rather have an engine with a new multi-layer head gasket anyways.
     
  10. StarCaller

    StarCaller Senior Member

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    JDM stands for Japanese Domestic Market, which refers to Japan's home market for vehicles and vehicle parts /
     
  11. rjparker

    rjparker Tu Humilde Sirviente

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    All gen3 Prius vehicles were made in Japan. A JDM engine is from a Prius that was sold and driven in Japan. When the car was junked, the engine was removed and sent to America for resale.

    Supposedly Japanese owners junk their cars with 50k miles or less on the engine. The pitch is they take care of the engine better so you get a used engine that needs nothing. The concerns include - Is it really a JDM engine or simply a worn out US driven 1.8L? Did cars destined for Japan somehow have better engines - say better rings and pistons? What year is a given JDM engine? No vins on these engines.

    Regardless many mechanics say they have good results with JDM engines. They claim no oil burning and high miles without further issues.
     
    #11 rjparker, Mar 26, 2024
    Last edited: Mar 26, 2024
  12. rjparker

    rjparker Tu Humilde Sirviente

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    #12 rjparker, Mar 30, 2024
    Last edited: Mar 31, 2024
  13. daley

    daley Junior Member

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    I got a JDM engine from Charlotte NC for $1287, it looks great on the outside, all the electrical and coolant connections look immaculate.

    intake and egr and intake ports all need a good clean, I wouldn’t like to guess the exact mileage but will keep you posted once its in.

    It does have tan colored injectors where the original ones are green, I will try the tan ones and see how they do.

    I am two bolts and a fuel line away from lifting the old engine out, probably get the new one in and finished up by middle of next week.
     
    bisco likes this.
  14. daley

    daley Junior Member

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    So I finally got the Jdm engine installed, went to start it today, it sounds pretty rough.

    when I rev it is sounds good but there is a loud knocking and vibration from what seems to be the transmission side of engine. this goes away when I rev it.

    Codes are for misfire on all cylinders.

    would there be a sensor in supposed to swap over onto Jdm engine?

    also could it be the egr valve? Car ran rough like this last time I swapped egr valve out, it went better when I put the old egr valve back. I’m tempted to try this first.

    any tips would be great
     
  15. rjparker

    rjparker Tu Humilde Sirviente

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    I would certainly check the egr, pcv (disconnected?), maf, map. Hopefully you did not have to do the timing chain?
     
  16. daley

    daley Junior Member

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    Could it be low battery voltage causing havoc?

    my 12v is at 11v, I’ve put it on charge and will try again later/tomorrow to see what’s happening.

    when I first started it I had throttle response, now I do not, it just runs rough and peddle does nothing.
     
  17. rjparker

    rjparker Tu Humilde Sirviente

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    If you get Ready the inverter supplies 13-15vdc power. Check all connections and hoses, often one or more is disconnected.

    Did you open the timing chain cover for any reason?
     
  18. daley

    daley Junior Member

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    No I havent touched the timing chain cover and everything looks like its connected properly.

    I do get ready mode so I guess my theory about 12v is out, although when I look with my scanner the ‘control module’ voltage is only at 11.4v

    I will see what happens after it’s charged a while, then I guess I will change out the injectors for the known working ones from original engine.

    I might throw a new set of plugs in too while I am at it.
     
  19. rjparker

    rjparker Tu Humilde Sirviente

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    11.4v in Ready is not right. It “runs” for more than 10 seconds?

    I would check the inverter connections as well.
     
  20. daley

    daley Junior Member

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    So i have tried swapping pretty much everything, injectors, sensors, map, maf egr, all came off known running engine. Battery showing 12.3v

    It seems to me like its not even trying to fire, peddle does nothing, even in power mode and all I get is a bunch of clatter from the engine in the transmission area.

    Could there be something wrong with the flex plate going to the transmission? It looked fine and lined and bolted up no problem.

    I’m stumped and I really don’t think this is a bad engine, but I guess it could be. Last thing to rule out is a new set of plugs.

    Is there anything I can look for using techstream that could show me what the car is looking for and not finding? .