Need help! Gas engine overheating. Cannot resolve.

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

  1. Grit

    Grit Senior Member

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    :ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO:
     
  2. rjparker

    rjparker Senior Member

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    Partial from
    4th-Generation Toyota Prius Teardown (Part 1) - MarkLines Automotive Industry Portal

    Stronger airflow in combustion chambers
    [​IMG]
    The re-designed intake port shape (Source: Toyota)
    The first improvement was changing the shape of the intake port based on an analysis of the "tumble flow," which is the vertical swirl of air-fuel mixture entering the combustion chamber. As illustrated in the image on the right, (1) the airflow was made straight and, (2) the inverse tumble component that blocks the tumble flow was reduced. As a result, the tumble ratio was improved from 0.8 to 2.8, the combustion velocity increased, and induction of a large volume of EGR (exhaust gas recirculation) gas became possible.

    The shapes of the combustion chamber and the piston-top surfaces account for the tumble flow described above.

    Large-volume cooled EGR
    The EGR distribution passage in the intake manifold has been restructured to a tournament design. This allows a larger amount of EGR gas to enter evenly into each cylinder.

    [​IMG]
    The intake manifold cross-section (Source: Toyota) [​IMG]
    The aluminum pipe at the left connects to the EGR passage


    [​IMG]
    An external view of the intake manifold[​IMG]

    The throttle valve (center)
    The intake manifold that directs air into the intake port is shaped so that it branches into two passages from the throttle valve, and supplies intake air into the respective ports after converging once at the collector located immediately before the cylinder head. This design ensures a smooth flow of intake air by increasing the cross-sectional area that the incoming air passes through, which minimizes air resistance and interference between cylinders.



    [​IMG]
    The EGR cooler configured at the back of the engine [​IMG]
    The EGR cooler unit


    A newly-designed water jacket spacer optimizes cylinder bore wall temperature
    [​IMG]

    The structure of the water jacket spacer (Source: Toyota)
    In order to achieve optimized cooling by means of the cylinder bore region, a water jacket spacer consisting of stainless steel and foam rubber has been adopted. This involves a foam rubber with a brand name of EXPAD being placed in the coolant passage at the bottom of the cylinder bore. This allows a large amount of coolant to flow over the upper part of the cylinder bore, which becomes very hot, and ameliorates knocking by raising the cooling effect. At the same time, allowing a smaller amount of coolant to flow to the lower half portion of the bore to maintain a high temperature. With these techniques, fuel efficiency is achieved by making the expansion factors of the upper and lower cylinder bore even, and piston action friction is standardized at a low level.

    Plus new inverter and hv battery design.
     
    #202 rjparker, Jul 6, 2021
    Last edited: Jul 6, 2021
    Raytheeagle, Mendel Leisk and jzchen like this.
  3. Mendel Leisk

    Mendel Leisk Sand Pounder

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    I think the “tournament flow” of EGR gasses through intake was adopted in a (2012 model year) revision, at least the concept: 1>2>4 passages, instead of previous 1>4.

    that was touted as a cure for the EGR blues for a while, then not so much.

    there are other improvements in 4th gen Exhaust Gas Recirculation though, intake location and increased volume.
     
  4. アレン・スピクタロン

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    I know this is quite an old thread, but it could simply be a stuck thermostat, have you tried removing the old one and replacing it with a new one?
     
  5. Jacob Bonner

    Jacob Bonner Member

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    Update: So I've been driving around the last few days with the thermostat taken out of the thermostat housing, running about 150-160 degrees Fahrenheit. I ordered a Dorman thermostat to see if I had any better luck with that than the Toyota thermostat. Replaced it today, gave it a test run and it was back to running at 220 degrees and higher... so I do think there is a separate issue causing the heating, apart from the thermostat. Perhaps it is the 3rd gen computer not being compatible with the 4th gen engine, as has been suggested.

    Anywho.. I removed the Dorman thermostat and put the Toyota thermostat back in. This time, I cut the jiggle pin with wire cutters and drilled the hole out to 3/16". Then I drilled two new holes about 1/8". Test drove it and it stayed around 175-185 degrees on the highway (upwards of 195 degrees when accelerating). I'm hoping to take it on the interstate in a few days to test it. It's slightly cool, but I'm not going to worry too much about it at this point. If I were to do it over again I'd probably just drill one additional hole.

    Note: not sure how I commandeered this thread. :oops: ... I'm thinking I moved to this one because I thought the problem was the water pump, which had been an ongoing conversation here. It's also entirely possible I'm a little a.d.h.d. :D
     
  6. michael hochmeyer

    michael hochmeyer New Member

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    HI SERGEY DID YOU EVER FIND OUT WHAT WAS THE CAUSE OF YOU OVER HEATING IN THE CAR ? I HAVE SAME SENERIO I ALSO TOOK APART THE EGR SYSTEM AND CLEANED EVERYTHING THIS OUT NO CODES JUST STILL OVERHEATS SAME AS YOURS . IF IF FOUND ANYTHING ELSE OR RESOLVED IT COULD YOU PLEASE LET ME KNOW ? THANK YOU MIKE
     
  7. Shahzad Nayyar

    Shahzad Nayyar Junior Member

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    Please check post 35
    Posted via the PriusChat mobile app.
     
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