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PCU coolant at low level

Discussion in 'Gen 4 Prius Technical Discussion' started by ykbj, Mar 6, 2019.

  1. ykbj

    ykbj Junior Member

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    In light of the event of Engine coolant inside catalytic converter | PriusChat

    Is it normal that my PCU coolant is just right above/almost touching the low level line. My Prius is only at 17k km and it's less than a year old.

    Prius Engine Compartment.png

    Part #7
     
  2. CooCooCaChoo

    CooCooCaChoo Senior Member

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    I think the dealership only fills it to the low level line at cold. If they were to fill it to the top, it would overflow when hot.

    So, as long as it isn't empty. Keep an eye on it.
     
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  3. alanclarkeau

    alanclarkeau Senior Member

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    Mine is a tiny bit below FULL - but the engine is hot - I've only been home a little while after a ½hr drive.
     
  4. kithmo

    kithmo Couch Potato

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    It should be between LOW when cold and FULL when hot, that's why it has two level indicators.
    If it's under LOW then it needs topping up (top up to Low level when the engine is cold), if it's over FULL then it is overfilled, if it's between then leave it alone.
     
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  5. alanclarkeau

    alanclarkeau Senior Member

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    I've been out for most of the day - just looked up the manual:
    upload_2019-3-6_23-14-16.png
     
  6. kithmo

    kithmo Couch Potato

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    OK, but according to that, when the engine warms up, the coolant will be over the full level.:unsure:
     
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  7. alanclarkeau

    alanclarkeau Senior Member

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    Could be - but there is heaps of space above "FULL" for it to expand. Not sure if it expands as much as the engine coolant - you can touch the top of the inverter (just), you're not going to touch the engine when it's hot.
     
  8. unigeezer

    unigeezer Member

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    the diagram shows the engine coolant reservoir, but where is the reservoir for converter coolant?
     
  9. ChapmanF

    ChapmanF Senior Member

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    See callout ⑦ in the illustration in post #1.

    If it is low, go ahead and top it to the FULL line. At operating temperature it doesn't expand as much as kithmo thinks.
     
  10. unigeezer

    unigeezer Member

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    If the engine coolant reservoir is a little bit below the full line, when the engine's cold, should I top it off to the "B" line?
     
  11. ChapmanF

    ChapmanF Senior Member

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    Only as one step in the process of refilling an empty system. It should end up at the FULL line once it has traded places with the air in the system.
     
  12. unigeezer

    unigeezer Member

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    Ok, thanks.
     
  13. a2058

    a2058 Junior Member

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    I overfilled it when I changed the coolant on the PCU by about 1/4 inch over the full mark with everything cold, that was 40000 miles ago. There it sat, never overflowed and it’s been totally ok.