Engine replaced, but new issue?

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by fos4110, May 20, 2026 at 12:23 AM.

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  1. fos4110

    fos4110 Junior Member

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    Hello all - I hope you can help with a dilemma I'm having with my 2014 Prius Plug-In.

    I bought the car used three years ago with 133K miles on it. It ran fine until I started experiencing engine issues.

    I replaced the engine in February and right after I replaced it I started noticing I slight "whirring" noise, especially when I coasted in drive and "b" mode. I especially hear it when I'm driving over 50 mph.

    I've been told by at least two sources it is the transmission, and one transmission shop told me it could run like this forever, or could go out at any time.

    I'm sure someone besides me have had this issue, and am hoping I can get some idea what my next step would be. FYI, the car currently has 260K.

    Thanks for your time!

    Mike in Tacoma
     
    #1 fos4110, May 20, 2026 at 12:23 AM
  2. Brian1954

    Brian1954 Senior Member

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    It could be a wheel bearing.
     
    #2 Brian1954, May 20, 2026 at 2:09 PM
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  3. bisco

    bisco cookie crumbler

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    post this in the appropriate gen 3 forum for more eyes, the drive train is the same, and there aren't many pip owners around anymore.
     
    #3 bisco, May 20, 2026 at 2:19 PM
  4. bisco

    bisco cookie crumbler

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    who did the work? what engine did you replace it with? I wonder if it could be the clutch.
    have you replaced the tranny fluid?
     
    #4 bisco, May 20, 2026 at 2:26 PM
  5. Brian1954

    Brian1954 Senior Member

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    I disagree. Do not create duplicate threads for the same problem for the car. Information is then scattered across two different threads, which becomes very confusing.
     
    #5 Brian1954, May 20, 2026 at 2:28 PM
  6. bisco

    bisco cookie crumbler

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    agreed. but he's not likely to get knowledgable engine advice here
     
    #6 bisco, May 20, 2026 at 2:32 PM
  7. Brian1954

    Brian1954 Senior Member

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    Who says it is an engine problem? It could be a drive line problem or a wheel bearing problem.
     
    #7 Brian1954, May 20, 2026 at 2:35 PM
  8. bisco

    bisco cookie crumbler

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    very possible, but still not likely to get much help in this dead forum
     
    #8 bisco, May 20, 2026 at 2:37 PM
  9. Brian1954

    Brian1954 Senior Member

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    Many people browse this PriusChat forum and look at "recent posts". They will see this thread just like you and I did.
     
    #9 Brian1954, May 20, 2026 at 2:40 PM
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  10. fos4110

    fos4110 Junior Member

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    Thanks for the reply. It was done by a reputable shop - used engine.

    He said that the transmission fluid was pretty dirty. They replaced it but it seems like it’s still dirty after some driving l. That’s why they think it’s a transmission


    was told I could either keep driving it and nothing would ever happen or it could go out at any time I’ve had it looked at a couple different shops, but I still have my suspicions
     
    #10 fos4110, May 26, 2026 at 4:45 AM
  11. fos4110

    fos4110 Junior Member

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    oof I’ve been checking this thread- not sure if I should repost?

    Wheel bearing sounds like a possibility but I’m no expert- please note that this sound was noticeable after the engine was replaced. Unsure if coincidence.
     
    #11 fos4110, May 26, 2026 at 5:00 AM
  12. rjparker

    rjparker Tu Humilde Sirviente

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    Don't use B mode as it will create noise on its own and has no legit purpose.

    Wheel bearing noise is most likely. These bearings will not get loose; they just make a noise that gets louder as you speed up. Normally with the engine running the noise is drowned out above 55. A decent mechanic would know the sound. You could get this diagnosed for free from a good independent suspension shop. Another possibility is the drive axle cv joints. There is nothing different in these parts from a non hybrid. Brake noise is also possible.

    Most transmission shops know nothing about a Prius eCvt transaxle which has no clutches, hydraulics or torque converter. They almost never fail. However I would ask the shop who swapped your engine if they changed the transaxle at the same time. Hopefully they did not.

    Sometimes it makes sense to have it diagnosed by a dealer and then seek advice on how to repair it.
     
    #12 rjparker, May 26, 2026 at 6:39 AM
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  13. ChapmanF

    ChapmanF Senior Member

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    B mode is kind of expected to come with a whirring noise, because it can make more use of the engine for slowing the car than D mode does. So you could just be hearing the engine doing what it's supposed to.

    But you're presumably using B mode about as often as you did before the engine swap, and you're saying the sound is more noticeable now? There could be various explanations for that....

    Maybe the replacement engine just sounds a little different. Maybe the way the shop tightened down the engine mounts is transmitting a little more sound to the cabin. Maybe B mode is making a little more use of the engine than before, because of aging of the battery or seasonal temperature changes or something.

    Can you record the sound?
     
    #13 ChapmanF, May 26, 2026 at 9:26 AM
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