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Front brakes seized?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by unigeezer, Feb 7, 2015.

  1. unigeezer

    unigeezer Member

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    I jacked up both front wheels and I can't move them at all. I was able to get the car into neutral and still they won't move. emergency brake off as well (even though that only stops the rear wheel) Could the disc brakes be too tight or could they just be on all the time somehow? I had noticed that when driving, it felt like the brakes were on. This feeling was especially evident when taking my foot off the gas pedal to glide on flat ground, and the car would slow down faster than I thought it should. Also notice a huge drop in MPGs. I know the car is FWD, so maybe there is supposed to be resistance but I can barely get either wheel to turn more than an inch or two.
     
  2. ursle

    ursle Gas miser

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    Got insurance?

    Get it towed to a dealer, they will read the obd2 and reveal the secret.
    Must be the actuator seized, honestly, tow it to an agreeable party.
     
  3. bisco

    bisco cookie crumbler

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    how many miles on her?
     
  4. nh7o

    nh7o Off grid since 1980

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    If there are no warning lights on, then there may not be any codes to read. It is possible that there is brake drag. The car is meant to be towable while in neutral. That gets the transaxle out of the way, supposedly. Turning a wheel manually would also be turning the differential gears, which should then be easy.

    If the brakes are locked up, then a short drive should heat them up a bit, which you can feel by hand. If not, then there might be a failed bearing in the transaxle case, which is rare but does occur. You might consider taking a wheel off and seeing if the brake pads are actually loose on the discs.
     
  5. ChapmanF

    ChapmanF Senior Member

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    So it really feels, I'm hearing, like the brakes are applied, even though the car is off and no one is pressing the brake pedal?

    I can imagine a way that could happen, though I don't think I've ever heard of it happening before. The brake power assist comes from an accumulator tank of brake fluid pumped to high pressure. Ordinarily it stays in the tank until you press the brake, and valving in the master cylinder admits some of the pressurized fluid. Valves in the brake actuator can also admit fluid from the accumulator. Perhaps if something isn't shutting off completely, the accumulator pressure could be constantly acting on the brakes.

    There is a way to bleed off the accumulator pressure. Every time you press and release the brake pedal, a bit of fluid leaves the accumulator and then eventually returns to the reservoir. If you press and release the pedal a lot of times with the ignition OFF (so the pump won't just run and pump it back up again), eventually you deplete the pressure. It can take around 40 pedal strokes. Normally it's very easy to tell when you're done: you get 30 or 40 pedal strokes that are easy and feel about the same, and the next one feels hard as a rock.

    In your case, if there might already be a funky valve, I can't guarantee it will feel that positive, but you should still eventually know the pressure is gone and all the fluid has returned to the reservoir (the level should be noticeably higher than it normally is).

    At that point ... don't turn the ignition on ... and try turning the front wheels again, to see if they are easier with the pressure relieved.

    If that makes a difference, I'll suspect something internal to the master cylinder/actuator, which won't be great news, but you could also check for anything dead simple like something in the way of the brake pedal preventing it coming all the way up....

    -Chap
     
  6. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Sounds like it. You need to have the front brakes inspected to figure out what is the problem.

    Even if the car is IG-OFF and therefore the shift selector is in P, if both front wheels are raised then you should be able to rotate each wheel. The wheels will rotate in opposite directions under that scenario.
     
  7. unigeezer

    unigeezer Member

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    Mystery solved. Took it to local tire/brake place and they confirmed that that BOTH calipers were stuck! They were able to get them open and then found that the guide pins were dirty and had ZERO lubrication on them. Cleaned and lubed them, put it back together and no more problem! Will be nice to get my mpg's back up to normal!
     
    Mendel Leisk likes this.
  8. bisco

    bisco cookie crumbler

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    no lube? shocking!:eek:
     
  9. unigeezer

    unigeezer Member

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    Well the guy said they looked pretty gunked up and mostly dry. When I drove away after the service (no charge!) I could immediately feel a big difference! Like a huge weight was lifted!
     
  10. bisco

    bisco cookie crumbler

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    you should have a word with the service man whollast inspected/serviced your brakes. sounds like they're charging you, but not actually doing anything.
     
  11. unigeezer

    unigeezer Member

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    I had new brakes installed several years ago, and never really did any maintenance on them since. From what I've been reading, seized or stuck calipers are not uncommon. Just happy it's fixed. Also, the last time I had them inspected was before they became stuck. I had only asked they they check the wear on the pads, not a take-everything-apart type inspection.
     
  12. Avi's Advanced Automotive

    Avi's Advanced Automotive Independent hybrid repair shop

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    The front wheels should turn easily when the car is jacked up and brake is not being pressed. If in park, the opposite wheel will turn backwards, but will turn. Was anything done to the car right before this happened?

    Avi
     
  13. bisco

    bisco cookie crumbler

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    see post #7