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2016 prius coolant issue

Discussion in 'Gen 4 Prius Main Forum' started by Sharnold, May 20, 2024.

  1. Sharnold

    Sharnold Active Member

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    2016 prius 170k miles client says overheated with white smoke coming out of the exhaust.
    Coolant and check engine MIL on dash.
    I scanned the car it had only one main P code P148F.
    After checking the oil ( no coolant mixture ) and the cylinders ( they was dry ).
    Tried using TIS to activate water pump and it would error out and fail.
    I pulled the water pump.
    It would not turn by hand.
    Replaced the water pump and the thermostat and plugs.
    Now there is no codes no rough idle but at 190⁰ the exhaust smokes terribly and there's no heat in the cabin nor does the system build pressure.
    The car runs smooth as silk.
    My ideology is the catalytic converter is busted leaking coolant into the exhaust system.
    Any other ideas would be appreciated.

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  2. BiomedO1

    BiomedO1 Senior Member

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    Yes, That would be my guess. Bypass the exhaust gas heat exchanger to see if your coolant levels stabilize. If it does, problem solved. 2016 and early 2017's has been know to have this issue, but at 170K - your probably outside TSB/OEM warranty on this.
     
  3. Sharnold

    Sharnold Active Member

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    With it still overheating I think it's just dumping into the exhaust and can't circulate the coolant correctly
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  4. bisco

    bisco cookie crumbler

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  5. Sharnold

    Sharnold Active Member

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    Unfortunately after I looped the system off the catalytic converter although it would build pressure and the heater core is circulating now it still overheats and the coolant reservoir tank is bubbling afterwards and the system looses pressure rather quickly so we all know what that means..........
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    #5 Sharnold, May 26, 2024
    Last edited: May 26, 2024
  6. bisco

    bisco cookie crumbler

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  7. Sharnold

    Sharnold Active Member

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    Yeah my guess is either the water pump failed and found the weakest spot which was the heat exchanger and the engine went low on coolant and overheated.
    The car lost all coolant through the exhaust causing water pump failure and it overheated.
    Either and or there's still no oil water mixture and the coolant will get to 250⁰ withing a 2 mile drive and it's still running smoothly.
    I think exhaust gas is circulating into the coolant system super heating it

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  8. jerrymildred

    jerrymildred Senior Member

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    That would be my 1st guess. There are tests for exhaust gas in the coolant.
     
  9. Sharnold

    Sharnold Active Member

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    Not the head gasket, so let's try to think about this logically. I replaced the water pump, thermostat, bypassed the catalytic converter that was leaking but im still overheating.
    Waterpump is coming on running TIS on active test.
    The cooling fans run fine but do shut off in park.
    I can't see any flow in the coolant reservoir but the lines do build pressure.
    But also loose pressure relatively fast.
    When it's doing properly the lower lines are stiff and hot
    When it's malfunctioning they get stiff but feel cool.
    The upper smaller lines on the radiator, radiator pipe to reservoir get hot everytime.
    Sometimes there's gurgling and flow bubbles coming off the small lines on that side of the reservoir will fill and empty on its own squeezing the larger hoses or by itself running ( the side with the bleeder Allen screw )
    I'm at my witts end.
    Bad new thermostat............ or?

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    #9 Sharnold, May 31, 2024
    Last edited: May 31, 2024
  10. Brian1954

    Brian1954 Senior Member

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    Did you buy OEM parts for the water pump and thermostat?
     
  11. Sharnold

    Sharnold Active Member

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    Pump yes thermostat no
    Pump failure would prompt a TIS fault and not run automatically or on active test.

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  12. Sharnold

    Sharnold Active Member

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    Replaced water pump and thermostat one more time still a no go.
    If I run water pump using TIS while driving the car set at 3000 it will stay cool
    If I let it do it's own thing is when it's overheating.
    Also checked and changed relays and fuses
    So I'm still not understanding wth is going on here

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  13. Brian1954

    Brian1954 Senior Member

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    What does Techstream show the pump is running at when the car is overheating. There should be two speeds listed. One for actual pump speed and a second one for requested pump speed.
     
  14. Sharnold

    Sharnold Active Member

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    It only registers the full 3k when you choose the 3k option
    If you turn off your active test it sits at idle
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  15. Brian1954

    Brian1954 Senior Member

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    Let me explain a little better what I was trying to ask you. You should be able to see live data in Techstream. I have not done it personally, but there should be a live data screen where you can view the actual engine coolant pump speed and also the speed that the ECU is requesting that the pump run at. So you can compare the requested speed versus the actual speed. This is not in the active test screen.
     
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  16. Sharnold

    Sharnold Active Member

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    I gotcha now
    I know how to access that easily
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  17. rjparker

    rjparker Tu Humilde Sirviente

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    How is exhaust gas still getting into the coolant? Did you bypass the exhaust heat exchanger at the exchanger? If not maybe the bypass is not right.

    Why is the water pump only running good under Techstream control? Bypassed temp sensor? Air is the system at the sensor or sensors?
    Gen4 coolant flow.jpeg
     
    #17 rjparker, Jun 4, 2024
    Last edited: Jun 4, 2024
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  18. Sharnold

    Sharnold Active Member

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    Bypass is correct
    Waterpump is running correctly after running live data.
    Still doing it
    I've done everything to bleed the air out of the system, including unbolting the reservoir and sticking it on top of the block squeezing hoses ETC.
    So am I having an issue with a selector valve malfunctioning, or is one of the temp sensors malfunctioning causing something to go amiss down the line.
    No leaks, no air getting pulled in.
    The heat is not working every time. And that whats throwing me off.
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    #18 Sharnold, Jun 4, 2024
    Last edited: Jun 4, 2024
  19. rjparker

    rjparker Tu Humilde Sirviente

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    Only overheats in traffic or when driving slow? Do radiator fans come on?
     
  20. Sharnold

    Sharnold Active Member

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    Fast or slow it overheats even in maintenance mode
    The fans cut on and off in maintenance mode and with driving they are on but in park will shut off
    If I pull from the garage and coolant temp is 165⁰ it'll hit 200⁰ within 2 miles and continue upwards to 230s with normal driving
    And of course the MIL will illuminate at 243⁰
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