Need help! Gas engine overheating. Cannot resolve.

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Sergey K, Apr 1, 2019.

  1. jzchen

    jzchen Senior Member

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    If you have a diagnostic scan tool it's time to watch/record live Data as you drive around...

    moto g(7) power ?
     
  2. Ragingfit

    Ragingfit Active Member

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    Hey, I thought about all that too. Here's a video about the subject.
    Take a look at 14:30




    Then cut the jiggle pin from the thermostat.
     
  3. Ragingfit

    Ragingfit Active Member

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    I agree with what you said about the EGR and I would like to say the reason for the EGR cooler is so the intake can be made of plastic..
     
  4. ChapmanF

    ChapmanF Senior Member

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    How would you like to say they do it for fuel economy?

    But yes, the "so the intake can be plastic" idea is a good additional example of the kind of "alternative explanation" we can spin out with a "plausible" sound—cooler makes the gases cooler? check ... plastics have temp limits? check—and then blow a lot of PriusChat breezes about it with none of us looking up the numbers in question to see whether the temp difference made by the cooler is really anywhere near what would make a difference to the manifold.
     
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  5. jerrymildred

    jerrymildred Senior Member

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    They spent a pile of money developing the EGR system and the manufacturing process to pave they way so they could spend another pile of money on new materials and manufacturing processes for the intake manifold.

    Nah. Only a government would do something that stupid.
     
  6. Ragingfit

    Ragingfit Active Member

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    Old EGR systems had no cooler. They were cast iron pintle valves plumbed directly to the cast iron manifold. It's more efficient to have a plastic intake for many reasons. I had nowhere to insert the reason for these coolers until your post. Thanks for the opportunity.
    - Fix That Prius !!!
     
  7. ChapmanF

    ChapmanF Senior Member

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    Forum readers are best served when the reason being inserted is the actual one.
     
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  8. Grit

    Grit Senior Member

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    no way, these scholarly people are too smart to put themselves in that situation!!! :ROFLMAO:
     
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  9. Jacob Bonner

    Jacob Bonner Member

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    Thanks for the video.

    I forgot to include that I backflushed the heater core with no success in fixing the overheating - it didn't appear to be clogged. Maybe it's not a clog but a small leak, preventing the system from pressurizing? Long before my engine swap in 2019, I had noticed that my windshield would fog up (a faint greenish color) in a parking lot even if nobody else's was fogged. My coolant is pink so I'm not sure why it would be a greenish fog. I may reroute the hoses to block off the heater core and see if that solves my overheating problem, to decide what to do further. I may end up trying to replace the entire heater core if I get any kind of success from blocking it off.
     
    #169 Jacob Bonner, Mar 11, 2021
    Last edited: Mar 11, 2021
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  10. Ragingfit

    Ragingfit Active Member

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    Replacing the heater core on a Prius is a VERY big job.
    Good Luck!
     
  11. Mendel Leisk

    Mendel Leisk Sand Pounder

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    I’ve seen pics, and it looks like open heart surgery on the dash.

    Just to gripe: WHY is that? Heater cores, and other heat/vent components, do fail. Follow the money I guess.
     
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  12. Ragingfit

    Ragingfit Active Member

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    It is installed as an assembly. Can't replace pieces of it, like a heater core, without pulling the whole thing.

    https://toyotaparts.mcgeorgetoyota.com/oem-parts/toyota-evaporator-assembly-8705047150?c=Zz1odmFjJnM9ZXZhcG9yYXRvci1hbmQtaGVhdGVyLWNvbXBvbmVudHMmbD0xJm49QXNzZW1ibGllcyBQYWdlJmE9dG95b3RhJm89cHJpdXMmeT0yMDE1JnQ9dGhyZWUmZT0xLThsLWw0LWVsZWN0cmljLWdhcw%3D%3D
     
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  13. ChapmanF

    ChapmanF Senior Member

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    I had a 1984 Ford Bronco II where the heater core really was a less-than-ten-minute job. The heater case was in two halves, one each side of the firewall. Take off a little cover on the inside (just reaching under the glove box), undo the hoses in plain sight on the engine side of the firewall, give the core a little tug and there it was.
     
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  14. Willy Toast

    Willy Toast Junior Member

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    My Oldsmobile 1984 was simple and easy to repair but it rusted completely away. All the wires and connectors were corroding in its 12th year. It had a head gasket leak ever since I overfilled the oil. It finally drove off with a temporary topping up of brake fluid to a guy who wanted the steel block engine. Those were the days when you knew exactly what was wrong. Now it is all quite mysterious.
     
  15. Jacob Bonner

    Jacob Bonner Member

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    @Ragingfit

    Hope you could advise on something: I blocked off the heater core and it seemed to run fine for about an hour. Next time I started up the car it resumed overheating like before. Strange, but okay. So my next plan is to block off the heat exchanger. The only way I've ever seen this done is by blocking it off near the valve, underneath the car. Is this necessary or can I just block it off in the engine bay, at those two aluminum pipes?
     
  16. ASRDogman

    ASRDogman Senior Member

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    What are you typing about???
    What gave you the notion to block the heater core?
    If you mean the engine was overheating.... You should check the water pump,
    and the thermostadt. Are you loosing engine coolant? You should be able to see
    the coolant flowing, while the engine is running, in the overflow tank. If you don't see
    movement, the water pump would be the thing to check.
    How many miles are there?

     
  17. Shahzad Nayyar

    Shahzad Nayyar Junior Member

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    When the temperature hits this high and youblift the bonnet, have u seen the coolant boiling? I went through all your posts. What if you have a faulty temperature sensor? The water pump can over rev to compensate for any faulty high temperature reading...
    Posted via the PriusChat mobile app.
     
  18. Jacob Bonner

    Jacob Bonner Member

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    Water pump has been replaced twice. Thermostat replaced twice. Heater core flushed. No coolant leaks. Replaced radiator. I've seriously done about everything else anyone ever mentions. I've taken it to dealership and they're stumped - they just want to replace the same parts I've already replaced. That is why I decided to block heater core (and because I suspect I have a slight leak in it - not enough to notice difference in coolant levels but enough to not be able to build pressure... at least that was my hypothesis. Didn't really work out though.)
     
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  19. Jacob Bonner

    Jacob Bonner Member

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    I have wondered that (about temperature sensor). I would have thought that if the sensor was faulty then I would be getting wild readings. In truth, I'm not sure what a faulty sensor would look like on an OBD device. I do know I am having an overheating problem though, because the coolant boils above 220ish degrees F. I have also checked the rubber hoses with my infrared temperature gun and they seem to match the readings that the temp sensor is giving (give or take, depending on the location of the hose). Nothing about this makes sense to me. I can try replacing the temperature sensor - I might as well since I've tried virtually everything else.
     
  20. ASRDogman

    ASRDogman Senior Member

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    Have you flushed the radiator? Flushed the block?
    Or a blocked hose? Don't remember, but was any sealer put in the collant?
    That would eliminate all the physical stuff.
    A bad sensor would give you false readings.
     
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