2015/123000 mile/Well Maintained/ Head Gasket Going?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by philr, Aug 21, 2024.

  1. philr

    philr Junior Member

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    I have been following the recommended maintenance suggestions to a T (even early water pump replacement and the EGR cooler cleaning) with the expectation that the head gasket on my 2015/123k mile prius would not fail. But I think it's leaking.

    Most of my driving is commuting and city driving, but last week I took an 8hr/500mi drive to visit family and the next morning at start-up the engine shook/cylinder not firing and then quickly cleared up. I drove the car during my visit without further problems and returned home another 8hr/500mi - no problems.

    I inspected the car when I got home and noticed the coolant jug fluid level was down about 1/4 inch from the full mark - all other fluids were correct. I have not seen any leaks or evidence of leaks. Could this be the beginning of a head gasket failure?
     
    #1 philr, Aug 21, 2024
    Last edited: Aug 21, 2024
  2. bisco

    bisco cookie crumbler

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    possible, but highly unlikely. fill the coolant and keep an eye on it.

    occasional startup misfires are common to the beast. coolant may be low or may have always been there, unless you have been watching it. you might lose a bit under normal circumstances as well.
     
    #2 bisco, Aug 21, 2024
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  3. Mendel Leisk

    Mendel Leisk Senior Member

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    It might be. Monitor the coolant level (say put a strip of masking tape on the reservoir, and mark current level with a Sharpie pen). Also obviously, see how the cold-starts go.
    You cleaned the EGR passages in intake manifold also?
    What miles did you do the cleaning at?
     
    #3 Mendel Leisk, Aug 21, 2024
  4. philr

    philr Junior Member

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    Yes that's my plan - monitor. I will plan on replacing it in the near future regardless. I can't take the chance of a failure a long way from home and it's more likely than not that the head gasket will fail.

    The egr and intake cleaning, tune up, water pump/2nd coolant change, pcv etc was completed at 90K.

    Thanks for the feedback.
     
    #4 philr, Aug 22, 2024
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  5. philr

    philr Junior Member

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    I am guessing that the issue I described will repeat itself more often to the point I will need to replace the Head Gasket/Bolts etc. I will say that if it turns out to be a head gasket the root cause is definitely a design failure and not poor or lack of maintenance. I have posted the maintenance to date below for reference.

    All Maintenance:
    Note: To date does not use oil and mileage 45+ mpg.

    Oil/Filter/Rotate every 10K from 0-90K miles with 10K synthetic oil and filter
    Oil/Filter/Rotate every 5K from 95 to Current miles

    45K Maintenance
    Oil/Filter/Rotate
    Wipers
    ICE Coolant Change and Bleed
    Inverter Change and Bleed
    Air Cleaner/Cabin Filter
    Cleaned Hybrid Battery Fan/Install Filter
    Tires
    All Fluids full and marked with a sharpie

    90K Maintenance
    Oil/Filter/Rotate
    Wipers
    Cleaned Hybrid Battery Fan Filter
    ICE Coolant Change and Bleed
    Water Pump
    Thermostat and Housing
    Spark Plugs
    PCV
    Clean Intake Manifold/Gaskets
    EGR Cooler/Clean Pipe/Gaskets
    EGR Rebuild Kit (Toyota)
    Brake Fluid
    Air Cleaner/Cabin filter
    Trans Fluid
    License Plate Bulbs
    All Fluids full and marked with a sharpie

    110,000 miles
    Oil/Filter
    Tires
    12v Battery
    Hybird battery replace with "Electron Battery"
     
    #5 philr, Aug 27, 2024
    Last edited: Aug 27, 2024
  6. Mendel Leisk

    Mendel Leisk Senior Member

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    Toyota USA recommends a “more in-depth” brake inspection, every 3 years or 30k miles. They’re vague as hell about specifics, and the Repair Manual is not much help, does NOT have a dedicated “brake inspection” instruction.

    You can let that slide some, but every 4~5 years at most, good to pull off the calipers, clean pads/shims, relube contact points, remaining pad thickness, that the wear is even, relube the slide pins. Maybe break out micrometer and dial indicator, check rotor too.

    you do need to be cautious: a good DIY ploy is to disconnect 12 volt battery for duration of caliper off rotor, and when everything reassembled pump brake pedal before 12 volt reconnect.

    also:

    toyota Canada recommends brake fluid replacement tri-yearly or 48k kms (30k miles).
     
    #6 Mendel Leisk, Aug 27, 2024
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  7. philr

    philr Junior Member

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    Coolant Update - 10/31/2024
    Miles 129744 (added 6744 Highway Miles since last post)

    I live in Asheville and due to the storm and no water/electric etc we decided to take a road trip in the Prius (to Montana to visit friends).

    The Prius performed perfectly, 42ish MPG and no breakdowns, no oil usage. The vehicle has since been serviced, inspected and the coolant level in the tank is down another 1/4 inch. There is no evidence of an external leak, and no evidence of coolant in the oil so my assumption is its burning it slowly. I will continue to monitor and update the results here.

    Thanks to all for your suggestions and follow up
     
    #7 philr, Oct 31, 2024
  8. ASRDogman

    ASRDogman Senior Member

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    You won't see oil in the coolant or coolant in the oil unless it's a BAD head gasket
    leak or cracked head.
    Part of your issue: "Oil/Filter/Rotate every 10K from 0-90K miles"
    It should be 5000 mile oil changed, with synthetic oil.

    NO reason for a new engine if the head is not cracked or warped. The head gasket
    would be enough. And with the low mileage, and a 2015 w/updated pistons and ring...


     
    #8 ASRDogman, Oct 31, 2024
  9. Mendel Leisk

    Mendel Leisk Senior Member

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    Boroscope inspect the combustion chambers, preferably first thing in the morning, a day after driving. Even better is to pressurize the coolant systme manually, which may accelerate the formation of coolant "tears" at the head gasket seam. You're looking for aforementioned tears, exceptionally clean piston top, and/or coolant pooling atop piston.

    My 2 cents, full EGR cleanout, including intake manifold's EGR passage, at a maximum of every 50k miles, will stave off head gasket failure. The longer you go betwen cleanings, the more the EGR departs from factory performance, basically reducing exhaust gas flow,, making what does get through unbalanced* ,and overly-hot exhaust gas.

    * Cylinder one tends to get starved first, while the rest are progressively more "ok", due to the sequential way the intake manifold EGR passages clog.
     
    #9 Mendel Leisk, Oct 31, 2024
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