Probably one of the last jobs a car owner ever thinks about is completely replacing the brake fluid in their car’s brake system. Most car makers suggest that you not only bleed your brakes on a regular interval and while replacing brake parts but that you also replace all of the fluid in your master cylinder and brake lines.
Although your brake system is a sealed system the fluid is very sensitive to humid air and will absorb water over time changing the fluid from a very light amber or yellow to a dark black.
Often you may notice this when you are topping off your master cylinder as your brakes wear. The fluid seems to turn as dark as engine oil.
This is an indication that it is time to replace the fluid in your brake system.
Although you can replace just the fluid in your master cylinder don’t expect this to cure the problem. As your brake system works old fluid will reenter the master cylinder and contaminate it. And this does nothing to improve the quality of fluid far out in your lines near your brakes.
When water is present in your brake fluid it will reduce its ability to compress as you depress the brake peddle. This can be an immediate problem causing your brakes to perform poorly when you first start your trip or it can get worse as your brake system heats up.
What You Will Need
If you have bled your brakes before then you know most of the process. In the best situation you are working inside on a car lift with a friend to help pump the brakes. However this job can be done by yourself in a couple hours with some basic tools and a floor jack & jack stand.
Since I am performing the work myself I have invested in a small hand vacuum pump to help suck the brake fluid out of the lines. You can pick up a decent one for about $35 – $50 and we sell them in the store.
Depending on the size of your vehicle you will need about 3 to 5 pints of Brake Fluid. When purchasing brake fluid for a Honda I suggest you buy Honda Fluid for other brands of vehicles you want to match the DOT Rating to your vehicle. NEVER MIX DIFFERENT DOT NUMBER BRAKE FLUIDS if you do you have a good chance of melting the rubber parts and seals in your brake parts and causing failure of your brake system.
If you are performing the work with a helper you will need a piece of plastic tubing about a foot long that will fit tightly over your brake bleeder valve and a plastic bottle to catch the waste fluid.
You will also need a socket and hand wrench that fits the size of your brake bleeder valves. They can range in size and most hand wrench sets only go down to 10mm … on this car a 8mm valve needed to be opened and closed so a small adjustable wrench was used.
Performing the Work
The first thing you need to do is empty the old fluid out of your Master Cylinder Reservoir. I used the hand pump to remove the fluid. If you use another tool you must make sure that it is new, clean and has never been used for petroleum products. A small meat injector or baster at a dollar store could work but never use it for petroleum products or it could contaminate your brake system and cause a burst of your seals.
Make note of the amount of fluid that you have removed. My hand pump canister has a level on it showing how much was removed and I need this number later when sucking fluid out at the brake bleeder because you never want the master cylinder to go dry. My indicator shows 80 ml was removed so when bleeding I will not remove more then 70ml at the brake bleeder.
Once you have removed the fluid there is likely to be some residue / gunk remaining so clean that with a clean lint free paper towel and possibly a qtip. Make sure not to leave fibers in the reservoir.
Refill the Master Cylinder Reservoir as high as you can above the top fill mark and replace the cap.
You will need to continually refill the reservoir as you bleed and flush each brake.
How To Bleed
Brake systems are split between front and back opposite sides to allow your brakes to continue to work incase there is a catestrophic failure at one of the brakes or in the brake lines.
Systems are setup so the Left Front and Right Rear…. then the Right Front and Left Rear are fed as pairs.
You must read your owners manual to get the correct bleeding pattern. In the case of this car it is front left – right rear – right front – left rear.
Crack open the bleeder valve with a socket wrench and 6 point socket to avoid stripping. Some fluid may or may not flow from the valve then close it.
Place a boxed end 6 point hand wrench on the bleeder valve then apply your plastic tubing line.
Connect the opposite side of the line to your vacuum pump or place into your plastic container that has the waste fluid from your reservoir. The line needs to be submerged in fluid if you are using the bottle method so it won’t suck air back into the system.
Vacuum Pump– if you are going to use a vacuum pump to suck the fluid out of the system start with the bleeder valve closed and build up pressure to about 25 pounds or more.
Open the valve and continue to suck the fluid out of the brake system never allowing the pressure to drop below 10 pounds.
REMEMBER your master cylinder holds 80 ml of fluid so do not remove more then 70 ml.
When you have reached 70ml close the bleeder valve and refill the master cylinder reservoir.
Continue to suck fluid out of the brake bleeder until the fluid is as clear as brand new fluid.
NOTE sometimes there is dirt buildup in your brake bleeder valve. If your system has this problem the vacuum pump may not be able to get the flow started. Place the bleeder valve tube into your waste container and depress your brake peddle once to clear the line. After that you should be able to use your pump as explained above.
TWO PERSON BRAKE BLEEDING METHOD
As above you should brake the bleeder valve free with a socket wrench then re-tighten lightly to close the valve. Place your box end wrench on the bleeder valve then your plastic 1 foot line from the bleeder to your waste container making sure it is submerged in fluid.
Remember that the Master Cylinder must never run out of fluid while you are bleeding. It will take about 10 or so strokes of the peddle to empty the master cylinder so count them and check as you go… On the first brake you want to check until a small amount is left in the reservoir then use that number of pumps as a base count to know when you need to add more fluid.
Starting with the bleeder valve closed have your helper pump up the brakes to get a full peddle then depress the peddle to the floor and hold it down not releasing it.
Open the bleeder valve and let the fluid come out then close it and tell your helper to release the peddle from the floor.
Call out the directions as this
You say DOWN….. then your helper depresses the peddle and says DOWN
You open the valve let the fluid out and close the valve.
You say UP and your helper says UP and he pumps the peddle for the next round.
You repeat and say DOWN and the procedure continues… NEVER open the valve until they say DOWN and make sure they repeat the commands when they are ready it may take them a few pumps to get a good peddle to allow you to bleed the fluid let them pump and then say DOWN.
Finishing The Job
After you have flushed all new fluid through all your brake lines you want to make sure that no leaks have happened from a partly closed valve or other problem.
After you complete each brake you should clean off any residual brake fluid with a can of brake cleaner.
Start your car and pump up your brakes about 30 times. Turn off the engine and pump an additional 10 times and hold your foot on the peddle as it is firm. If there are any tiny leaks you should be able to see them at the bleeder valve.
If you do not have a firm peddle it may mean that drum brakes are out of adjustment or that your pads have worn a serious amount and need replacing.
Another problem could be the seals in your master cylinder or a variety of other problems that we cant cover right here.
If your brakes performed Good before the flushing / bleeding but are now much worse there is a possibility that you introduced air into your brake system during the procedure.
You can repeat the process again and it should take less fluid to get the air out or you may need to have your car looked at by a professional.
NOTE when using a brake bleeder vacuum system never allow the pressure to drop to zero or a low amount. As long as you have good vacuum on the bleeder valve from the pump you should not be introducing air into the system.
Working on automotive Brakes is a skill that can be easily taught however because of the many differences in makes, models and systems it is impossible to provide the exact details you need to be able to perform this task on your own for the first time… DO NOT RELY ON THIS HOWTO as your only source of information … THIS HOWTO IS ONLY AN EXAMPLE OF ONE CASE and it MUST NOT be applied to any other car even if it is of the exact type, make, model. ALWAYS USE MANUFACTURE’S DIRECTIONS AND MANUALS and never attempt working on your brakes without full knowledge that you obtain from a source other then this HowTo.
BE SAFE … spend the money for a mechanic to do the work if you need to.