1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Seeking Guidance on a Persistent Car Cooling Issue

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Brickphx, Sep 13, 2023.

  1. Brickphx

    Brickphx New Member

    Joined:
    Sep 12, 2023
    3
    0
    0
    Location:
    Phoenix,az
    Vehicle:
    2011 Prius
    Model:
    Four
    Hello fellow car enthusiasts,

    I've been grappling with a rather vexing automotive issue for approximately six weeks now, and I'm turning to this forum in search of some much-needed advice and expertise. The problem initially manifested itself as the dreaded red coolant temperature warning light flickering to life while I was cruising along the freeway. Interestingly, I discovered that turning off the air conditioning during freeway driving (at speeds of 60-70mph) would typically extinguish the warning light after a couple of minutes. There were a few instances where I failed to notice the warning light and didn't deactivate the AC, which subsequently triggered the check engine light. Fortunately, the check engine light tended to disappear after a day or so, as long as I managed to avoid triggering the coolant temperature warning light.

    Upon closer inspection, I noticed dried coolant residue along the passenger side of my vehicle, and the coolant reservoir appeared to be consistently low on coolant. My initial response was to top up the coolant reservoir, and this seemed to alleviate the issue for about a week. However, the problem resurfaced, with the warning light recurring, followed by coolant spraying out of the reservoir. In an attempt to remedy the situation, I experimented with running the car in maintenance mode, raising the coolant reservoir and leaving the cap off to expel any trapped air, suspecting vapor lock as the culprit. Nevertheless, I'm still grappling with the issue, albeit in a somewhat different manner.

    Then, I stumbled upon this video (
    ) and decided to give it a try. Remarkably, it appears to have resolved the problem, at least for the time being.

    Here are my questions:

    1. Could there be any potential drawbacks or side effects associated with the YouTube-suggested fix, which involves removing the O-ring from the coolant reservoir cap?

    2. I've noticed a small hole at the back of the reservoir cap housing, which seemed like it might have been intended for a hose at some point. It acts as a funnel when refilling coolant, preventing leaks. Should this hole be there, or am I overlooking something? I'm considering sharing a picture for reference.

    3. I'm open to any additional advice or suggestions you may have to offer regarding this puzzling issue. Your insights would be greatly appreciated.

    Thank you in advance for your assistance, and I look forward to your input on this matter.
     
  2. JC91006

    JC91006 Senior Member

    Joined:
    Nov 10, 2013
    16,438
    8,372
    0
    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    what you have is probably a bad head gasket, which is very common for these Turd generation cars. I would try to add coolant in maintenance mode and bleed as much air out as possible and then monitor the coolant level. But honestly speaking, if you're losing coolant, it's already too late
     
  3. Brian1954

    Brian1954 Active Member

    Joined:
    Jan 31, 2021
    492
    190
    0
    Location:
    South Central PA, USA
    Vehicle:
    2011 Prius
    Model:
    III
    Does your engine shake, rattle, run rough during a cold engine startup? If so, you may have a bad head gasket.

    How many miles an your Prius? When did you buy it, and what was the mileage?

    Your description of the engine overheating and pushing coolant out of the tank could be caused by an engine water pump that is going bad. You will notice this mostly at higher engine loads, like driving 60mph+ on the highway.

    You need to get this fixed ASAP because overheating of the engine can lead to the head gasket going bad.

    Posted via the PriusChat mobile app.
     
  4. Mendel Leisk

    Mendel Leisk Patron saint of newly poured sidewalks

    Joined:
    Oct 17, 2010
    54,032
    37,894
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    What’s the miles?

    have you had the car since new?
     
  5. BiomedO1

    BiomedO1 Senior Member

    Joined:
    Mar 27, 2021
    1,189
    646
    0
    Location:
    SacTown, Ca
    Vehicle:
    2021 Prius Prime
    Model:
    LE
    Welcome!!

    There's a very good chance it's a head gasket issue. If you don't know how to properly test for a head gasket issue, you should take it to a professional, that's a Prius specialist.
    It could also be a occlude radiator. Probably from someone putting a head gasket sealer product into the cooling system. That way they can coverup the worst of the head gasket failure to sell the car to an unsuspecting party.
    This could also be the result of a high mileage water pump that's about to fail, but overheats usually happens in stop & go traffic. The fan and water pump can't remove enough heat from the engine. If your moving down the highway, there's a 65 mph breeze going through your condenser and radiator.

    Hope this helps....
     
    Mendel Leisk likes this.
  6. ttou68

    ttou68 Active Member

    Joined:
    Sep 9, 2017
    341
    198
    0
    Location:
    40509
    Vehicle:
    2010 Prius
    Model:
    III
    I would suggest check for fault codes, using ab OBDII reader or auto parts store usually do it for free..

    Possible cause..
    Water pump, thermostat, or air in system, also possible blown head gasket...


    Posted via the PriusChat mobile app.
     
  7. Xterra72

    Xterra72 Senior Member

    Joined:
    Oct 20, 2013
    1,358
    1,634
    0
    Vehicle:
    2013 Prius
    Model:
    Persona
    Replace engine water pump and thermostat for good measure.
     
  8. jzchen

    jzchen Newbie!

    Joined:
    Apr 9, 2012
    3,284
    1,003
    0
    Location:
    Arcadia, CA
    Vehicle:
    2012 Prius v wagon
    Model:
    Five
    Sounds like your heater pathway has a leak. So once you turn off the AC system it stops flowing and losing coolant.

    Whether you want to try a stop leak only a very few of us on here would consider it. The no sayers tend to say they fail to work, but also say they tend to clog the tiny tubes in the cooling system, which is to be fair, contradictory….
     
    Brickphx likes this.
  9. Brickphx

    Brickphx New Member

    Joined:
    Sep 12, 2023
    3
    0
    0
    Location:
    Phoenix,az
    Vehicle:
    2011 Prius
    Model:
    Four
    Subject: Urgent Help Needed: Overheating and P261C Code After Coolant Overflow

    Hey fellow car enthusiasts,

    I hope you're all doing well. I'm reaching out to this forum in desperate need of help and guidance. Currently, I'm going through an extremely tough time and find myself living out of my car due to challenging circumstances.

    Recently, I experienced a concerning issue with my car while driving. As I was attempting to top off the coolant, the car unexpectedly took in a considerable amount—approximately a gallon and a half. In an attempt to address what seemed like an insatiable need for coolant, I added more. Suddenly, the car's warning lights illuminated, resembling a Christmas tree, and it eventually stalled on the road.

    After managing to get to a safe parking spot, I noticed that the coolant had overflowed from the reservoir. To make matters worse, the check engine light came on, and upon scanning the car, I received a P261C code.

    I'm aware that this code pertains to the engine coolant pump "B" control circuit/open. Considering my challenging circumstances, I'm seeking advice on the most cost-effective way to address this issue. I'm not in a position to invest heavily in repairs, but I need my car to be operational for both shelter and transportation.

    If anyone has experience or knowledge related to this issue or suggestions for budget-friendly repairs or troubleshooting steps, I would be immensely grateful for your insights and assistance.

    Thank you for taking the time to read my post, and I appreciate any help you can provide.

    TO ANSWER SOME OF THE ABOVE QUESTIONS AND ASSUMPTIONS... I AM THE SECOND OWNER OF THE CAR, HAVE HAD THE CAR FOR THE LAST 5 YEARS, HAVE NEVER USED ANY SORT OF QUICK FIX TO COVER ANY PROBLEMS AND THIS IS THE FIRST ISSUE OF THIS MAGNITUDE. CAR ENGINE SOUNDS FINE, DOES NOT SHAKE AND WAS ABLE TO BE DRIVEN 4-5 MILES FROM WHERE IT DIED TO MY FRIENDS HOUSE WHERE I CAN WORK ON IT. I HAVE CHECKED THE OIL FOR MIXING OF COOLANT AND THERE DOES NOT SEEM TO BE ANY NOT SURE IF THIS IS THE ONLY WAY TO RULE OUT A HEAD GASKET BUT I DONT BELIEVE IT TO BE THE ISSUE YET. THANK YOU ALL, YOUR ALL AWESOME. SOME MORE THAN OTHERS LOL.
     
  10. Brian1954

    Brian1954 Active Member

    Joined:
    Jan 31, 2021
    492
    190
    0
    Location:
    South Central PA, USA
    Vehicle:
    2011 Prius
    Model:
    III
    You did not respond to the questions that were asked two weeks ago. You did not do anything about fixing this problem until you severely overheated your engine. Now, it may be time to replace the engine.

    Posted via the PriusChat mobile app.
     
    Kromis likes this.
  11. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    7,355
    4,292
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    If it is the water pump you will not see flow from the bottom hose of the reservoir after the engine is fully warmed up. It is about a $300-$400 job at some shops.

    Odds are it is something else based on this:
    You masked a head gasket problem by relieving coolant pressure. A failed water pump back then would not have been “fixed” by this hack. The video was correct when they said it can temporarily mask early hg symptoms.

    You were virtually out of coolant at this point. Too much water under the bridge (car) now.

    I will assume no cash or credit resources. I would suggest moving the car to your place of employment and start saving for an engine. These engines are not built for overheating longer than maybe 5 minutes.
     
    #11 rjparker, Oct 3, 2023
    Last edited: Oct 3, 2023
  12. jzchen

    jzchen Newbie!

    Joined:
    Apr 9, 2012
    3,284
    1,003
    0
    Location:
    Arcadia, CA
    Vehicle:
    2012 Prius v wagon
    Model:
    Five
    As I understand the car is at a friend’s house where it can be worked on. (That’s a good friend btw).

    IF one is to save up for a replacement engine at this point, what is the down side of trying one of the more “reputable” fix a bottles? Is there a core credit that one loses if that is found by the recycler/rebuilder?
     
  13. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    7,355
    4,292
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    No downside for the old engine. I might bypass the heater coil and factor in a possible radiator down the road.
     
    jzchen likes this.
  14. douglasjre

    douglasjre Senior Member

    Joined:
    Sep 13, 2008
    1,719
    604
    0
    Location:
    Orlando, FL
    Vehicle:
    2010 Prius
    Model:
    ----USA----
    Diagnostics?