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Did Prius do away with the the thermos.

Discussion in 'Gen 4 Prius Technical Discussion' started by padroo, Dec 30, 2017.

  1. padroo

    padroo Senior Member

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    My old 2008 Gen 2 had the thermos to hold hot coolant for quicker warm up. Did they do away with it?
    I don't hear the Gen 4 making the sound.
     
    #1 padroo, Dec 30, 2017
  2. Elektroingenieur

    Elektroingenieur Senior Member

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    There is no coolant heat storage tank on the fourth-generation Prius. I assume Toyota’s engineers decided the improved exhaust heat recirculation system (developed jointly with Sango Co., Ltd., and described in SAE Technical Paper 2016-01-0184) and the new active grille shutter system made it unnecessary.
     
    #2 Elektroingenieur, Dec 30, 2017
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  3. Fester

    Fester Active Member

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    I think the thermos was dropped after the gen 2. My '08 did have one and I always knew the sound the thermos pump made for a few seconds following shutdown. Although lengthy, YouTube has some excellent videos by Weber Auto showing systems and changes from each generation of Prius and one I linked (on the active shutter thread) shows the gen 4 coolant system with the shutters and a detailed look at the exhaust system heat exchanger for faster warmup.
     
    #3 Fester, Dec 30, 2017
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  4. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    No thermos on 3rd gen. I believe it was the gen that introduced coolant heating through the exhaust, too.
     
    #4 Mendel Leisk, Dec 30, 2017
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  5. padroo

    padroo Senior Member

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    I must have missed that episode that John Kelly does for Weber State in Utah. I will be looking for it today, thanks for the info.

    I found the YouTube video about the Gen 4 Prius cooling system, excellent video.

     
    #5 padroo, Dec 30, 2017
    Last edited: Dec 30, 2017
  6. pilotgrrl

    pilotgrrl Senior Member

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    One of my sisters called that sound "the dialtone".
     
    #6 pilotgrrl, Dec 31, 2017
  7. Tideland Prius

    Tideland Prius Moderator of the North
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    Yeah just the Gen 2 had the thermos.

    The exhaust heat recirculation system took care of the warm-up cycle.
     
    #7 Tideland Prius, Dec 31, 2017
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