Easier to swap in a used engine or do a head gasket replacement?

Discussion in 'Gen 3 Prius Technical Discussion' started by weapon, Jul 9, 2026 at 9:37 AM.

  1. weapon

    weapon Junior Member

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    Looks so simple to swap in a used engine vs the head gasket.

    Am I correct?

    What are some of the pitfalls of a swap?
     
    #1 weapon, Jul 9, 2026 at 9:37 AM
  2. JC91006

    JC91006 Senior Member

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    a pitfall would be the used engine you put in will have more problems than the one you're replacing. But since you have a 2010, considered the worst engine year for 3rd generation, it probably would benefit you more than the potential pitfall to swap engine
     
    #2 JC91006, Jul 9, 2026 at 10:44 AM
    Last edited: Jul 9, 2026 at 12:24 PM
    Mendel Leisk and weapon like this.
  3. weapon

    weapon Junior Member

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    Yes that is a major concern I do have right off the bat. I have been watching the head gasket replacement videos and it seems really labor intensive and lots of places for user errors if not careful.

    When I did the manifold/egr swap, I was looking at the engine and it seemed like a relatively simple engine swap. It just seems to be a very well enclosed process. I would for sure try to get a low milage 2015 replacement.
     
    #3 weapon, Jul 9, 2026 at 10:51 AM
  4. ASRDogman

    ASRDogman Senior Member

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    How many miles do you have on the engine? Is it burning oil?
    Replacing the head gasket is less expensive. As long as the head is not warped.
    Did the engine overheat? If you are replacing it because it JUST started leaking, you're likely okay.

    Replacing the engine is not really a "hard" job, just a lot of steps. If you go slow and take your time,
    you'll be able to do it if you have the ability.

    But putting a used engine in, is risky. Do you KNOW it's from a 2015? Do you KNOW if the mileage is
    actually the REAL miles. How well do you trust the people you'll getting the engine from?

    It would be best to get a remanufactured engine.

     
    #4 ASRDogman, Jul 9, 2026 at 11:48 AM
  5. weapon

    weapon Junior Member

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    It is the one with the pink goop issue from my other post. Almost 200k. Been burning oil for the last 5 years. 1& 3 spark plugs were coated in oil when removed during the cleaning. Got it all back together and the pink goop has returned. I also noticed that the torque power is lower on this one vs my 2010 with only 160. Every day I drive it, she just keeps hinting to me it has head gasket issue. Not fully blown but small leak.

    After more research, with the oil burn and the head gasket, I might be better to just find a 2015 engine and do a swap instead of putting a bandaid over the probably ring issue.
     
    #5 weapon, Jul 9, 2026 at 12:30 PM
  6. Mendel Leisk

    Mendel Leisk MMX GEN III

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    Maybe ask @Tideland Prius to merge threads?
     
    #6 Mendel Leisk, Jul 9, 2026 at 12:33 PM
  7. weapon

    weapon Junior Member

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    [QUOTE="ASRDogman, post: 3618873, member: 165042"

    But putting a used engine in, is risky. Do you KNOW it's from a 2015? Do you KNOW if the mileage is
    actually the REAL miles. How well do you trust the people you'll getting the engine from?

    It would be best to get a remanufactured engine.[/QUOTE]


    At this point, there are tons of these on/off the road. There is a makeshift cottage industry near my area where the local Russians and Serbians have full lots of crashed gen 3. A lot of them still with lower mileage running engines (60-100k). So finding a good donor is not really a problem. 2015 specific might make the search a bit harder. Since the car is still running, not overheating and driving fine, I can keep going for a long while i search.

    A remanufactured engine is $4k+. I can get a whole new used prius for near that price and not have to do any work.
     
    #7 weapon, Jul 9, 2026 at 12:42 PM
  8. weapon

    weapon Junior Member

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    Different question entirely than that thread. Not trying to diagnose an issue but to get opinions on an engine swap vs head gasket.
     
    #8 weapon, Jul 9, 2026 at 12:44 PM
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