Questions on bleeding the 456M brake system - do's and dont's | FerrariChat
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Questions on bleeding the 456M brake system - do's and dont's

Discussion in '456/550/575' started by pietersnodt, Jan 27, 2024.

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  1. pietersnodt

    pietersnodt Rookie

    Jun 23, 2020
    19
    Full Name:
    Pieter Snodt
    #1 pietersnodt, Jan 27, 2024
    I purchased a '99 456M GTA a while ago and have improved many things on the car, changed most of the gaskets, filters, fluids, tackled the typical seat and pop-up light issues and did many more things to improve the overall condition of the car.

    The last thing I need to do is bleed the brake system because while driving, I felt that the brake pedal was absolutely not responsive enough.

    I have bled brake systems in older models like the 308 and Mondial, but this is the first time I do it in an ABS/ASR model, with a hydraulic ECU in between the booster and the callipers.

    So, I thought the typical bleeding (under pressure) would do the trick: put an extra reservoir on top of the brake liquid reservoir to make sure it doesn't run out of fluid while performing the procedure and then from the rear RH side, LH side, front RH and LH side calliper sucking the liquid through the pipes.

    I thought I was all done, but when turning the ignition key, the brake pedal went all the way down to the floor. Conclusion: that didn't work.

    Now, I have read through many posts in this section, but there's no fully documented procedure to be found, only fragments.

    My main questions are:

    1. Does the engine need to run or must the key be in "on" position before starting the procedure? So the ABS/AST block is activated?
    2. What about the 2 bleed nipples on top of the brake master cylinder. At what moment do these need to be bled?
    3. Is the sequence the same as with other cars: first RH rear, then LH rear, then RH front and finally LH front calliper?
    4. Manual bleeding: is pushing the brake pedal allowed to bleed the brakes instead of using a pressurised system?

    All input is welcome.
     
  2. pietersnodt

    pietersnodt Rookie

    Jun 23, 2020
    19
    Full Name:
    Pieter Snodt
    #2 pietersnodt, Feb 1, 2024
    great! Thanks for your help .
     
  3. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    28,762
    socal
    #3 fatbillybob, Feb 1, 2024
    In my experience sucking does not work. The same seal break that allows old fluid to flow also allows lower pressure air to be sucked and fool you into thinking you get a good bleed. Pressure is the way best done 2 man but Pressure through Master does work. At home I alway bleed 2 man. Trackside I'm a one man band and bleed with a full reservoir and about 15psi pressure.

    Models are different. On 348 key on will cycle abs as you bleed. Others that does not work and best cycled via factory tool. I don't bother and just find a wet patch hit brakes active abs to move fluid and bleed. If you keep fluid well maintained you don't have to do as complete a bleed. For example if you wait 10 years to change rusty 5 year life coolant....yeah you are going to go after block drains.
     
  4. pietersnodt

    pietersnodt Rookie

    Jun 23, 2020
    19
    Full Name:
    Pieter Snodt
    #4 pietersnodt, Feb 23, 2024
    So, I did it with an air pressure based tool: put an extra reservoir above the brake fluid reservoir and from back to front sucking the fluid through the lines at the brake calipers. Then, final thing is to bleed both master cylinder nipples. Then all was fine.
     

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