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2016 gen 4 no cabin heat no leaks

Discussion in 'Gen 4 Prius Main Forum' started by Loots, Dec 17, 2022.

  1. Loots

    Loots Junior Member

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    Three Touring
    After hours of searching I guess it’s time I start to ask questions.

    About 2 weeks ago I started to hear what I can only describe as gurgling sounds from under the dash while sitting warming up. I still hear it but now no cabin heat. I have lost no fluid in the system and controls seem to work fine. No work has been performed to the cooling system since new as I bought the car new in 2016 and have 170k on it. I have maintained the car such as oil changes every 5k miles, air filters and spark plugs but haven’t touched the cooling system. At first I thought possibly the thermostat, but after a TON of reading here, I’m not so confident that is actually the problem. Water pump perhaps? An ideas where to start looking?

    I have owned old cars (currently a ‘36 Dodge pickup) and have worked on most all my vehicles, but this Prius has me absolutely stumped. I do own a lift as well, so getting under it if necessary is no big deal.

    Thank you for any help or ideas where to start before I throw in the towel and pay a local to perform the work (which I hate to do).
     
    #1 Loots, Dec 17, 2022
  2. jdenenberg

    jdenenberg EE Professor

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    Since you have not done any cooling system maintenance in 170k miles of use, you are about 70k miles overdue. At this point you should do a full cooling system flush and hope that there are no blockages in the two separate cooling systems in your Prius (one for the engine and the other for the hybrid synergy drive and the power electronics). Each has its own water pump as well as ecu controlled valves.

    I stick to using Toyota's super long life coolant which is good for 50k miles after each coolant drain/refill.

    JeffD
     
    #2 jdenenberg, Dec 17, 2022
    Doug McC likes this.
  3. sclevine

    sclevine Active Member

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    I had the same EXACT symptoms before I noticed my coolant tank was empty. Coolant leak. Double check that. Catalytic converter needed to be replaced. Happening to many of us now it seems.
     
    #3 sclevine, Dec 17, 2022
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  4. BiomedO1

    BiomedO1 Senior Member

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    Yep; the 2016 and 2017 exhaust heaters are notorious for leaking coolant into the tailpipe. Some dealers has actually talked people into replacement engines and head-gasket jobs on their misdiagnosis.

    The gurgling sound means it's unlikely the water pump; since that needs to be turning to make that sound - assuming the coolant is making the gurgling sound. Check both coolant reservoirs. Turn on the car and set the heating system for front wind shield defrost. This should start the ICE and let you more closely diagnose the problem. Run the torque app and keep an eye on your engine temperature and feel the hoses for coolant movement. If still no heat; check to the coolant valve @ the internal heat exchanger. Make sure it's opening up.

    If you engine thermostat is stuck open; you'll likely have a pending P0128 or it will soon throw a P0128.

    Hope this helps.....
     
    #4 BiomedO1, Dec 18, 2022
  5. Jburner

    Jburner Member

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    I’ve heard the gurgling sound from the tailpipe. Is that normal?
     
    #5 Jburner, Dec 18, 2022
  6. jdenenberg

    jdenenberg EE Professor

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    That probably means that you are losing coolant in the catalytic converter heat exchanger. You can bypass that heat exchanger as was discussed in some other threads and avoid replacing your catalytic converter. This problem is common in 2016 and 2017 Prii as they age.

    JeffD
     
    #6 jdenenberg, Dec 18, 2022
    BiomedO1 likes this.
  7. BiomedO1

    BiomedO1 Senior Member

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    That may be normal; condensation boiling- out of your exhaust system.
     
    #7 BiomedO1, Dec 19, 2022
  8. Jburner

    Jburner Member

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    There isn't any condensation or coolant loss. I just hear it. I assume that that's normal? I just never noticed it before because I'm always in the car driving. :)
     
    #8 Jburner, Dec 20, 2022
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