What is the proper way to replace the brake fluid in a car? What tools are required? I want to make sure I do not get any air or bubbles in the system as this is something that needs to be done right the first time for obvious safety reasons.


3 Answers 3


There are a number of ways this can be done. It can range from a two person job, with on one the pedal and the other at the bleed nipple, to a one man job where the new fluid is forced through the system under external pressure.

For DIY purposes the most common is the two man (person?) way. Person A is at the nipple, which has a hose attached and the other end is submerged in a jar with some brake fluid in it, opens and closes the bleed valve. Person B is at the brake pedal and presses down when A tells him to, which should be just before A opens the bleed valve.

Once the pedal has been depressed (not too suddenly) person A closed the valve and tells B to release the pedal. The procedure is repeated until no more bubbles are seen to come out. It's vital to check the fluid level regularly, because if it drops too low you have to start allover again.

Tools required:

  • Ring spanner to fit the nipple. Don't even think about trying this with an open-ender - you'll simply round it over.
  • Hose to fit the nipple.
  • Coffee jar or similar with a little brake fluid already in it.
  • A helper who can follow simple up/down directions and can put up with you growling when they get it wrong.
  • Brake fluid. Preferably a different colour to what is currently in the system, so that you will know when the old stuff has been fully pushed out.
  • Rags to clean the nipple before starting and clean up the spillage that always seems to happen.
  • "Brake fluid. Preferably a different colour" I haven't ever seen this. Where would you get it from? Commented Mar 30, 2011 at 4:13
  • @Larry, some of the higher end fluids are colored. I've seen blue, red and green I believe. Also, depending on age of the old fluid, you may be able to tell just from the new fluid being clear vs old being dirty.
    – ManiacZX
    Commented Jul 11, 2011 at 13:15
  • Does the car/truck need to be running when bleeding brake? I have a brake booster and wondering if it's more efficient to do it when running. Commented Jul 31, 2011 at 23:01
  • I believe coloured brake fluid is region specific as ATE Blue is outlawed in the USA simply because it isn't the prescribed colour for brake fluid defined by law. Commented Apr 29, 2016 at 13:01

If your car has ABS (Anti-Lock brakes) you should ensure that there's no requirement to purge the ABS pump after flushing the old brake fluid out of the system. Not all cars w/ ABS have this requirement, but you should check.

Sometimes the purge process requires use of a diagnostic scan tool or other proprietary interface to cycle the system which can only be done by the dealer or qualified repair facility.


Check out this http://en.wikipedia.org/wiki/Brake_bleeding

  • 2
    Welcome to Motor Vehicle Maintenance and Repair! Whilst this may theoretically answer the question, it would be preferable to include the essential parts of the answer here, and provide the link for reference. Commented Mar 30, 2011 at 7:28

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