Coolant loss- any connection to a fuel injector

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by C Clay, Dec 2, 2025 at 6:06 AM.

  1. C Clay

    C Clay Member

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    Last week I was tooling along with my 2014 at 354,000 miles. all of a sudden it consistently started the death rattle, and it eased up pretty quick. But it was consistent every time. I use that app called scanner app, and it never gave a count of misfires, but the only data it did pull was that they occurred around 1300 RPM and although the check engine light didn’t come on, if you read the codes, the P301 was there.

    I did the head gasket replacement about 100,000 miles ago, new OEM spark plugs, clean the manifold ports, EGR cooler.

    I got to thinking about the advice to do a fuel system cleaning or at least just run some good Chevron fuel system cleaner.

    I followed the instructions on that, actually ran my gas tank to about as empty as it could possibly be,… Not on purpose it just happened that way. I ran into Walmart with 0 miles left to go.

    Anyway, the death rattle has stopped. Coincidence, just luck? doesn’t matter either way I was still pretty happy… Until I noticed that it looks like 3/4 inch of antifreeze has gone down in the reservoir.

    What would be the next order of inspection or replacement? I’m thinking probably spark plugs would be the next place to go. And then the EGR cooler. any thoughts?
     
    #1 C Clay, Dec 2, 2025 at 6:06 AM
  2. BiomedO1

    BiomedO1 Senior Member

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    Stick a borescope down 1&2 to see if it's been steam cleaned. The coolant just didn't evaporate????? You can just throw a set of plugs at it , but I serious doubt it's going to solve your issue - long term.....
     
    #2 BiomedO1, Dec 2, 2025 at 10:36 AM
  3. Mendel Leisk

    Mendel Leisk MMX GEN III

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    Was that the last time you cleaned the EGR system?
     
    #3 Mendel Leisk, Dec 2, 2025 at 12:14 PM
  4. C Clay

    C Clay Member

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    Yes it was. I cleaned the intake manifold, but I didn’t have the energy for the EGR cooler.
     
    #4 C Clay, Dec 2, 2025 at 6:32 PM
    Mendel Leisk likes this.
  5. indel

    indel Junior Member

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    You also need to clean the EGR valve in addition to the cooler. If the valve is stuck open or closed, that will screw up the amount of exhaust gases going into the intake per unit time.
     
    #5 indel, Dec 2, 2025 at 10:12 PM
  6. Mendel Leisk

    Mendel Leisk MMX GEN III

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    The valve and cooler are two peas in a pod, just for the record; don’t think it’s possible to remove one without the other, they come out together.
     
    #6 Mendel Leisk, Dec 3, 2025 at 1:08 AM
  7. rjparker

    rjparker Tu Humilde Sirviente

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    Dynamic Duo of tests to rule out egr or confirm head gasket

    Start with no cost egr block flow test


    At about 10:15 in the video he starts talking about the egr valve letting "air" into the intake manifold. He means exhaust gasses.

    A blocked egr cooler won't cause death rattle or misfire codes. A sticking open egr-valve can cause rough low speed engine operation. Both will cause an egr code. Neither will cause loss of coolant.

    Car Care Nut HG Borescope at 660s
     
    #7 rjparker, Dec 3, 2025 at 1:56 AM
    Last edited: Dec 3, 2025 at 2:05 AM
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