My cap was loose on my master cylinder could i have air in my system now?

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  • Anonymous
    3 years ago
    Best Answer

    Unlikely. Providing the fluid level is correct.

    However brake fluid can absorb water from the atmosphere, and in excess, that can be somewhat dangerous if it gets to the brake cylinders and they get hot under heavy braking. The water can boil and turn to steam, driving the brake fluid out of the cylinders. The reservoir should never be left uncovered, most master cylinder tanks have a flexible rubber diaphragm that allows fluid to get lower as brake pads wear, but separates the fluid from open air to avoid it picking up moisture.

  • 3 years ago

    but just like OIL brake fluid SPOILS over time. If it is BROWNish get a full POWER BLEED. Many REAL car companies insist that you do this every 2-3 years. It is an ESTER compound that absorbs moisture from the AIR> in a HUMID climate itlasts even LESS time. The CAP OFF for a small period can cause MILD aceleration of the break down process. GOOD LUCK

  • 3 years ago

    Not unless all the brake fluid was gone form the reservoir.

    Source(s): Mitsubishi Master Tech
  • 3 years ago

    Not from that. Air only enters when there is a failure of the wheel cylinder or caliper seals.

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  • don r
    Lv 7
    3 years ago

    Not likely.

  • Scott
    Lv 6
    3 years ago

    Not necessarily, but if the cap was loose the brake fluid could have absorbed moisture or other contaminants. You should probably have the brake system flushed and bled.

  • Anonymous
    3 years ago

    You probably do have air in the system anyway. You have to bleed it out at each caliper to get all of it out. Most people would never notice if there was few tiny bubbles.

  • 3 years ago

    Not from a loose cover. The cover is there primarily to keep dirt out of the master cylinder's well. If the well is empty or there is a breach in the brake lines air can get in.

    • Daniel3 years agoReport

      My pedal went to the floor thats how i discovered my cap was loose and i tightened it and now my brakes work again but are a little spongy. Could i have just lost the pressure? Will it rebuild pressure?

  • 3 years ago

    There is ALWAYS air above the brake fluid in the master cylinder. Unless you lost fluid, you should be OK.

    • Daniel3 years agoReport

      My pedal went to the floor thats how i discovered my cap was loose and i tightened it and now my brakes work again but are a little spongy. Could i have just lost the pressure? Will it rebuild pressure?

  • br549
    Lv 7
    3 years ago

    Only if all the fluid leaked out.

    • br549
      Lv 7
      3 years agoReport

      In your silly answer you say "


      There is ALWAYS air above the brake fluid in the master cylinder" Thus the ONLY way for air to enter from the master cylinder is if all the fluid has leaked out.

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