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can master cylinder break with brake flush?

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  • can master cylinder break with brake flush?

    I was planning on flushing my brakes this weekend, using the brake pump thingie I bought from bavarian autosport. my dad mentioned to me though that a mechanic had told him on the older bmw's that the master cylinder is made of plastic and could crack or break under pressure. is there any validity to this comment?

    youd think that under hard braking and everything else, that it would be tough enough. and the alternative would be to just not flush the brakes ever?

    yes, Searchy!, i have done a search on this but didnt find much about this in particular.

    has anyone ever had any problems with the master cylinder breaking? anything i should watch out for then when i do this? i've done it on my old e30 and e36 with no problems.

    lemme know, thanks -Will

  • #2
    It won't hurt the actual MC, but you may want to keep the pressure in the gadget to a sane level so that the plastic reservoir is not blown.


    • #3
      ok, so the only issue is the plastic resorvoir? I usually try to pump slowly enough so that the pressures dont get too high. 1 canister of the Ate blue should be enough, right?


      • #4
        Do not let the reservoir go empty and you'll be fine. Besides, you ARE NOT going to flush the system with 3000psi; are you?


        • #5
          You can pressure bleed the system with 15 psi. Don't go higher than 20 psi! I have heard that the reservoir will fail at 30 psi (2 bar), but I've decided that I don't need to prove that so I've never tried.



          • #6
            I'm with Dean, 15psi is plenty to bleed the system.
            Another issue with using a pressure bleeder is that the feed line for the clutch is not meant for high pressure, it can pop off of the reservoir if put under pressure.


            • #7
              Ok, sounds good guys. thanks for the reassurance. i'll be sure to keep the pressure at 15psi.