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Is this a problem?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Setheroth, Oct 6, 2015.

  1. Setheroth

    Setheroth Junior Member

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    So I did this to one of my front caliper Pistons. (Notice the chips gone on the edge of the piston hollow area and the hairline crack running down the sleeve) What do you experts think? Problem or no?

    It happened while using a C-clamp on the edge of the piston trying to push it back in. (Friggin brake actuator) :mad:
     

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  2. se-riously

    se-riously Active Member

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    Yes, it's a problem. Replace the caliper. And next time, use a block of wood to compress the piston and distribute the load more evenly, rather than compressing directly onto the piston itself.
     
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  3. Setheroth

    Setheroth Junior Member

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    I was kind of afraid I would get that response..

    So, like what could happen if I drove on it? Haha. I really can't make heads or tails behind the engineering of this piston.. Most are just metal in which case something like this would be a non-issue.., but this one seems like ceramic with a metal sleeve or something...
     
  4. Setheroth

    Setheroth Junior Member

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    In the interests of being thorough (and potentially saving $600), can anyone explain to me how this damage could cause an issue? I talked with a couple of mechanics over the last 24 hrs (including a Toyota technician), and they both said it should be ok. (the Toyota tech did hesitate a little bit)

    I've come to respect forums like this as a place for great technical information and that's kind of what I was hoping to get I guess..

    Thanks guys!
     
  5. Mendel Leisk

    Mendel Leisk Senior Member

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    I can't really see anything from your picture. Is the brake still opened up, could you try again. If there's a minor chip on the edge of the piston, probably ok. But regarding your mention of "hairline crack running down sleeve": what do you mean by "sleeve"? Is that crack on the inside wall of the piston? Or the rubber boot?

    That piston looks like it's waaay back in btw. Is the front face recessed, further back then the caliper face? No point to pushing it back too far.
     
  6. Setheroth

    Setheroth Junior Member

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    "Is that crack on the inside wall of the piston? Or the rubber boot?"

    It is on the inside wall of the piston. I guess it's hard to see - apparently the photo was de-resed when I uploaded it.

    The crack runs along that inside sleeve from the tip of the lower-most chip to about half-way down the depth of the wall. I hope I explained that where you can understand what I mean.. The rubber boot is untouched

    And yeah [after failing to push the piston in with my [somewhat dumb] edge-pressing technique I was able to re-position the c-clamp to the inside center] and pushed the piston in till it stopped.. It was probably 2-3mm past the caliper face when I took this photo

    Of course it came back out after I re-installed and let the brake actuator run for a few seconds.
     
  7. Mendel Leisk

    Mendel Leisk Senior Member

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    Just for reference, here's a pic of ours, one of the fronts, on an angle:

    Capture.JPG

    Looking at your pic, I'm still grasping at straws, trying to see the chips and/or crack. The couple of anomalies I see are marked up here:

    Capture.JPG

    Is the cracking at one of those zones? Or somewhere else? Say on an anolog clock face, what hour would it be at?
     
  8. The Electric Me

    The Electric Me Go Speed Go!

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    Others may be able to give you much more specific technical advice and opinion.

    My comment would be this.

    Regardless of whether you get told by X amount of technicians or even posters whether it would be OK or not. Damage has been done. And IMO it's damage to your brakes. Brakes, like tires, not something I take unnecessary risk with. Failure in the system can lead to life changing devastation. I would surmise it's not so much the chips or hairline crack you can visibly see and exists upon inspection of the brakes while the vehicle is not being used, but the potential outcome of repeated USE of brakes with chips and a hairline fracture.

    My advice is purely "untechnical". But I think a $600 dollar investment into making sure your brakes are at 100% functional capability is something that is a worthy investment. I don't want to depend on brakes, that only have a "might" be OK, or probably be OK seal of detached approval.
     
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  9. Mendel Leisk

    Mendel Leisk Senior Member

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    All our Hondas over the years had machined aluminum pistons. Guess you have to be real careful with Toyota's plastic ones. :(
     
  10. Setheroth

    Setheroth Junior Member

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    Ok, I guess a picture is worth a thousand words lol

    I'm not sure what the areas are that you were asking about. Definitely not damage tho or it would have jumped out at me when I was physically looking at it the other night. I think the one on the right is just a little scratch from moving the C-clamp over it. Have no idea about the area on the left but I'm sure it's just a minor scratch and a non-issue. Areas 1, 2, and 3 are what I'm talking about. The hairline crack is the red line that runs off of area 3.

    Electric, of course you are right about not taking chances with your brakes. That's actually why I'm posting here and trying to understand how it all works and what level of risk is involved with this. Thanks!
     

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  11. Mendel Leisk

    Mendel Leisk Senior Member

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    Ok, gotcha, just very hard to see crack without mark up. Cheapest route would be to (DIY) disassemble that caliper and install a new piston, then bleed the brakes. The biggest issue there is bleeding the brakes I think: the system is very fussy. I believe it can be done without Techstream, but it's tricky. If you get it done through a dealership likely the most time and $ efficient is that they swap in a rebuilt.

    That would be the path of least resistance for me.
     
  12. yeldogt

    yeldogt Active Member

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    I don't think you can/ could get a new piston. The dents in the piston are not going to cause a problem -- the crack would have to extend to a point where the fluid would leak out .

    Does the crack extend over the top? The piston is captive

    How much are the new ones ?
     
  13. NutzAboutBolts

    NutzAboutBolts Senior Member

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    Looking at the picture, this is in my opinion and my opinion alone. If it was me, I would try to resurface the piston to prevent any sharp edges that can cause it to damage the piston boot. As long as the boot is intact and not damaged or leaking fluids, to me, it should be fine. If the boot is damaged, it can cause the piston to seize up due to dirt getting into it and can cause brake failure and/or engage to the brake pads.

    This is my opinion on what I would do with my car. If you feel unsafe, replace it and get a new one.
     
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