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Brake Issue

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Aleckmo, Oct 15, 2022.

  1. Aleckmo

    Aleckmo Junior Member

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    I just replaced my front driver side caliper piston, but I have to press brake pedal several times to see it moves. Also, the pedal is now spongy, so I don't see any leaks. I would be grateful if anyone could help me with this.
     
    #1 Aleckmo, Oct 15, 2022
    Last edited: Oct 15, 2022
  2. Aleckmo

    Aleckmo Junior Member

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    Okay, I got the answer, posting here so that it might help someone. When you replace brake fluid or rebuild brake caliper, you will need to bleed your brakes which is easy to do. You just need someone to press and hold break pedal for a few times while you loosen and tighten the brake bleeder screw until the fluid starts to come out "clean".
     
    #2 Aleckmo, Oct 16, 2022
    SFO likes this.
  3. ChapmanF

    ChapmanF Senior Member

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    The above is correct.

    That was correct for older cars. In a Prius, it is not that easy.

    It can be that easy, if all you did was rebuild a front caliper, and the only air in the system is right there. You can get away with bleeding the fronts by pedal pumping. That's why it worked for you this time.

    If you did the same thing in the rear, bleeding is even easier: the system will pump for you.

    If you just "replace brake fluid" and do it right, without letting any air in anywhere, then no bleeding is needed, and you can use some simplified procedures for the replacement.

    If any air gets in at the top of the system, the only way to safely and completely bleed it is with Techstream or another scan tool that can command the brake ECU to operate all the necessary valves to chase all the air out.

    A search in this forum can find many threads with more details on all of that.
     
    #3 ChapmanF, Oct 16, 2022
  4. Aleckmo

    Aleckmo Junior Member

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    I'm not the guy who spends $$ for oil change at dealerships only because they have special tools. We are talking about a common method of bleeding which doesn't need any scan/special tools.
     
    #4 Aleckmo, Nov 16, 2022
    Last edited: Nov 16, 2022
  5. ChapmanF

    ChapmanF Senior Member

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    Right, and you're talking about a method that won't work on a Prius.

    You can get away with it sometimes, if the only air in the system happens to be in the right places.

    You can also think you got away with it, if you get the air out of the passages used in the most common braking scenarios, so those feel fine, until you're in a less common braking scenario.
     
    #5 ChapmanF, Nov 16, 2022
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