What else should be replaced when replacing the water pump?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by gatorback, May 5, 2026 at 9:52 PM.

  1. gatorback

    gatorback Junior Member

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    A 2010 (16 y.o) Prius with 95K miles was inherited and I would like to prevent any damage. As I understand it the water pump should be replaced because of its age?

    If that is correct, what other parts should I replace while I am in there?
     
  2. CR94

    CR94 Senior Member

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    My impression is that coolant pump failures at such low mileage are rare, assuming it hasn't been coping with overheated coolant.

    When the pumps have to be replaced, people often replace the coolant thermostat at the same time, because it's easy then. However, I've yet to hear of an original thermostat actually failing at any mileage.
     
  3. PriusCamper

    PriusCamper Senior Member

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    I still don't understand why Gen3 owners have been so passive about engine destroying ability of this valve failure via class action lawsuits? Head gasket failure due to a stuck valve boosting engine temperature is a smoking gun... Guess its not common enough for outrage of significance?
     
    #3 PriusCamper, May 6, 2026 at 12:08 AM
    Last edited: May 6, 2026 at 12:21 AM
  4. Mendel Leisk

    Mendel Leisk MMX GEN III

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    Which valve? Maybe pre-edit?

    IMG_3852.jpeg

    ^ got this alert too, Priuschat snafu?
     
  5. PriusCamper

    PriusCamper Senior Member

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    I got confused when reading this first time around and thought OP was mentioning a different valve, rather than just the EGR valve itself. Once I realized it, I edited you and Chapman out of me asking for help, but notification was already sent.

    Point being this is the first thread I've seen that specifically said valve was jammed and forcing engine temperature higher. As in cause and effect, which is much less vague than how others have presented EGR issues in the past.
     
  6. ChapmanF

    ChapmanF Senior Member

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    Looks like maybe you mixed up this thread with the other recent one where the exhaust heat recirculation system was being discussed. That system has the little wax-thermostat actuator down on the exhaust pipe that waggles an exhaust valve, controlling whether the exhaust goes straight through the pipe, or has to go through the EHRS heat exchanger and heat up the coolant. If the valve gets stuck in the latter position, it heats up the coolant more than intended.

    In that other thread, rjparker posted graphs of the two temperature sensor readings, one at the engine water outlet, and one at the coolant return from the EHRS exchanger. The graphs show that your signal of the sticking valve is likely to be a temperature-warning light because of the EHRS temperature reading, while the engine temperature reading stays relatively tame. So you get notification of the EHRS issue and, ideally, go unstick it. I'm not sure how much excitement should be attached.
     
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