Take the 2-minute tour ×
Motor Vehicle Maintenance & Repair Stack Exchange is a question and answer site for mechanics and DIY enthusiast owners of cars, trucks, and motorcycles. It's 100% free, no registration required.

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.

share|improve this question

3 Answers 3

up vote 10 down vote accepted

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.
share|improve this answer
    
"Brake fluid. Preferably a different colour" I haven't ever seen this. Where would you get it from? –  Larry Mar 30 '11 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 Jul 11 '11 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. –  Gabriel Mongeon Jul 31 '11 at 23:01

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.

share|improve this answer

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

share|improve this answer
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. –  Rebecca Chernoff Mar 30 '11 at 7:28

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.