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Seat Toledo MK2 Brakes Calipers

Discussion in 'MK1 & MK2 Toledo' started by barrymurphy, May 13, 2019.

  1. barrymurphy

    barrymurphy Active Member

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    Hello,

    I have a strange issue that I am hoping someone can shed some light on.

    My left rear caliper will effectively stay on when you use the brakes a few times and will release itself but only after a few minutes.

    It is not a sticking piston. I have removed the piston, cleaned it, it is in very good condition and I replaced the seal.

    The strange thing is that as soon as I open the bleed nipple a little the caliper will release. So the piston moves back when the pressure released and that is why I am saying it is not the piston.

    I am not sure what is happening here. The caliper seems to be in good working order but pressure is building up in the caliper and slowly releasing.

    Its as if something else is causing the pressure not to release, something further back the line. I have replaced the rear hose to eliminate that.

    So what else is causing this? Can there be something else wrong with the caliper? There is not much to them.

    Another thing I should mention is that when you remove the caliper the fluid will not flow. If you press the brake pedal it will spurt out, but without the pedal pressed there is nothing flowing. Could this be related?

    It is as if something is making the fluid stay where it because you you cut the pipe, which I did, the cut section is full of fluid and it pours out but the section still attached to the car retains the fluid.

    This is only affecting the left rear. All others calipers are fine.

    I have never seem this on a car before and I have replaced a few dodgy calipers in my time.

    Thanks

    Barry
     
  2. chriswales6

    chriswales6 Active Member

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    There may be a restriction in the brake line stopping the pressure releasing or may be the handbrake isn't fully releasing on that wheel.

    Given the age of the car, new brake lines and possibly a new caliper would be worth trying. Had a rear caliper replaced on my 2003 Leon last year.
     
  3. barrymurphy

    barrymurphy Active Member

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    Thanks for that.

    Would the handbrake be involved? Would a faulty handbrake mechanism cause this even with only the footbrake being used?

    Also, could air be causing this somehow? The cylinder went dry a few weeks ago but I bled the system and all was fine for a while and suddenly this.
     
  4. chriswales6

    chriswales6 Active Member

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    Not sure to be honest, the handbrake works on a level that operates on the caliper. That may be getting stuck.

    You could also try bleeding the brakes again. But in my experience I've found it's better to replace a caliper once they start playing up.

    Had a rear one rebuilt then failed the MOT a few months later because of it. So had it replaced, they don't cost that much these days.
     
  5. Gokiwi64

    Gokiwi64 Geriatric Member

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    These calipers are notorious for failing, one of the common failure points is that dirt and debris gets under the weak seals around the hand brake mechanism effectively jamming it.
    Disconnect the handbrake cables from the caliper and then check how free the lever actuator is . Id be surprised if you had full movement in either of them.
     
  6. Brimfull

    Brimfull Active Member

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    Sounds like new caliper is needed to me

    Sent from my SM-G960F using Tapatalk
     
  7. barrymurphy

    barrymurphy Active Member

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    update - I pulled the fuse from the ABS as I was confident that the calipers were fine and I replaced the line on saturday.

    Voila, the issue is gone and the rear passenger no longer locks.

    I stopped the car and replaced the fuse and slowly the issue returns after pressing the brakes lightly a few times. Then when it starts happening and you slow the car to very slow it starts trying to bind harder and will bring the car to a stop. You can drive on if you accelerate as the brakes on the other three wheels are not on. But it is trying its hardest to stop you.

    So the question is - is this the abs wheel sensor and if so would this tell the abs to lock one wheel or would it try to engage on all 4 wheels or.....

    is this air in the abs module causing the locking of one wheel?
     
  8. barrymurphy

    barrymurphy Active Member

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    UPDATE

    The brakes worked well but there was binding on one wheel but there was another issue where no fluid would flow to the rears when bleeding, (fluid would come out when the pedal pressed but not of its own accord), and indeed when you disconnected the two pipes coming from the MC to the ABS there was no fluid flowing from them either (again would flow when pedal pressed). This suggested a blockage of some type in the MC. The binding could still have been an ABS issue as it affected only one wheel? Or could it have been a return issue where fluid is not allowed return properly after the pedal is released but I read somewhere that this would have affected at least two wheels and not one?

    Anyhow, I found the cause of the non flow. The bottom bolt on the MC was too tight against the servo and so pushing the piston in a fraction too much. As soon as I loosened it just a bit fluid started flowing. So one issue resolved.
    I also removed the ABS and used compressed air and brake cleaner through the ports to blow out any crud and clean the valves.

    I am hoping this will be my problem resolved but will not know until tomorrow.

    My question is whether the problem at the MC could cause the binding at one wheel or did I indeed have two separate issues?

    Barry
     

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