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Round 3 Overheating issues

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Joele3, Jul 30, 2019.

  1. Joele3

    Joele3 Active Member

    Joined:
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    Location:
    Bay Area
    Vehicle:
    2010 Prius
    Model:
    III
    Took a break from troubleshooting. But i'm back at it once again. Got an IR gun to measure temps all the different hoses. Pretty much all of them read around 176 degrees. Only big drop I noticed was the hoses going from heater core they was a 20 degree drop on one of the hoses. Interesting, so I decided to bypass the heater core.

    Slapped in a new water pump. I ordered a different brand. Advance Auto/ Carquest locally here in the Bay area. 230$ with 20% off online. Ended up being an Aisin brand with usual markings scratched off. Came in a carquest premium box.

    Reservoir wouldn't bleed properly until I raised it above then I started seeing bubbles rise up.


    Noticed my temps stabilize and drop down. Wow everything looks good. Before they would just keep increasing at idle over 100c I would just shut off after that. Went for a drive 30-45mph, no high temps. Ok lets try the freeway, went 65-80mph nice temps comparable temps to my V. All looks normal. After 20 minutes a few loops back and forth i'm not getting too far from home. I noticed the temps start increasing at 3/4 throttle. Going up passed 95c hitting 102c woah. As soon as I let go of throttle the temps drop quick. 5-10c drop within 2-3 seconds. Get home let it idle, water pump starts whining. Shut off let cool down. Jump back in the 2010 drove one block temp started at 85c to 101c in a quickness. Water pump code P261b car shuts off. I limp back home. Next day I pressurized the system up to 15psi and it held pressure no leaks. Pulled the water pump off, it seized up! I checked all my grounds coming from the harness that normally bolts up on the valve cover on 2010 motor. On the 2016 you have to move the grounds.



    I decided to check thermostats. I boiled all of them. They all opened up later than what its stamped on them. 95c fully open at 85c no movement not till around 92c I start to see some movement. I have 3 OEM and 1 Motor Rad brand which states 82c on the inside and oem has it stamped on the plastic housing. The aftermarket brand thermostat the spring is so stiff compared to oem.

    My question is if I were to bypass the heat exchange. What direction does the coolant flow out of the EGR cooler? Just trying to find out where my issue is. Thermostat and or heat exchange staying open while hot when it should be blocking flow out of exhaust. Water pump just can't keep up coolant flow. I did replace the thermostat located in heat recovery tank.

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    SFO and Raytheeagle like this.
  2. tankyuong

    tankyuong Senior Member

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    Vehicle:
    2012 Prius c
    Model:
    II
    Sounds like air still in system
     
  3. Raytheeagle

    Raytheeagle Senior Member

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    Vehicle:
    2019 Prius Prime
    Model:
    Prime Plus
    I have 2 used water pumps here with me if you want them;).

    Have you tried using the bleed screw at the top of the egr cooler to make sure there isn’t a pocket of air there?

    Good luck and keep us posted (y).
     
    SFO likes this.
  4. Joele3

    Joele3 Active Member

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    2010 Prius
    Model:
    III
    I have it loose while filling the system till coolant drips out then close up. I'll pop it loose with car running until I see a steady stream of coolant. Whats weird is sometimes coolant will just stop flowing out of it other times it spits out. I'm leaving it open for a good 30 seconds. Coolant will flow then stop a few drips then nothing. I"m not trying to make a mess of coolant all over my firewall. The hose coming from the T near the reservoir. The hose near driver side would get hot but not the one going down to radiator and reservoir. I pulled the hose off drivers side and coolant sprayed everywhere I was surprised how much pressure that little hose has.

    The spigot comes from the EGR cooler and back to the recovery system. I hit the EGR cooler with a pressure washer in all orifices. Where the coolant goes in also where the carbon builds up. So much easier with a pressure washer.
     
    Raytheeagle likes this.
  5. Joele3

    Joele3 Active Member

    Joined:
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    2010 Prius
    Model:
    III
    I took out the thermostat and bypassed the heat exchange. Been driving last few days 10-15 minute drives. Today had the courage to drive it to work 30 min drive on the highway. Water pump still going, temp peaked going up the Sunol grade at 82c but been hovering around 65c. 25 mins into the drive I started to smell smoke. Smoke coming from one of the heat exchange pipes. Most likely residue from the coolant. I blew it out a few days ago. Once I got to work I used compressed air and another half cup came out.

    I plan on driving it like this for another week. Going to put thermostat back in and leave heater exchange out of the loop. Weird thing I jacked the car up to inspect the heat exchange. Make sure the spring operated door for the back pressure exhaust was open. The actuator was stuck open fully extended. The car has been sitting for a few days so it was cold.

    Haven't been able to set catalyst or oxygen sensor monitor. The EGR monitor set no pending codes. Cold start up seems to be the same.

    The smoke didn't smell like coolant. Very similar to a new catalytic converter smell fresh metal getting heated up.
     
  6. Joele3

    Joele3 Active Member

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    Vehicle:
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    III
    I put the thermostat back in, rerouted hoses into the heater core but bypassed the heat exchange recovery system. Temperatures are in line what I see as normal operating temps. I compared to my 2014 V anywhere from 85c to 94c. I've put 500 miles on since. Drove in 103 degree weather with AC full throttle going up the Sunol Grade. I'll be taking a trip down to Recycle road and looking for an exhaust pipe. I seen one on craiglist for 250$ which was a steal in Sacramento. Its the catalytic converter + heat exchange system all in one. All monitors set no pending codes. Its funny the prius with all the sensors doesn't have one for the thermostat. I know some cars if you pull the thermostat it will throw a code for coolant temp under thermostat rating.
     
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  7. Boston2008Gen2

    Boston2008Gen2 Junior Member

    Joined:
    Sep 7, 2012
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    Location:
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    Vehicle:
    2012 Prius v wagon
    Model:
    III
    Can you please explain "rerouted hoses into the heater core but bypassed the heat exchange recovery system."?

    I want to bypass heater core but wanted to understand what you have posted here.