Obviously, it matters a lot to know how to change your brake fluid and when it is time to do just so. The fact that brake fluid provides hydraulic pressure to actuate your brake system’s pistons and provide braking makes it necessary. And it also conducts the hydraulic pressure that stops the vehicle. This incompressible fluid operates in a high-pressure, hot environment of 100 to 200 degrees at normal operating conditions.
Therefore, brake fluid has a high boiling point; this boiling transforms the fluid into gas. Unlike liquid, gas is compressible, and therefore the presence of gas bubbles in the brake system could lead to brake fade or failure. Unfortunately, brake fluid is hygroscopic, meaning it attracts and absorbs water from the atmosphere. Water in brake fluid will boil at a much lower temperature and can corrode brake components as soon as possible.
Why Does Brake Fluid go Bad?
Brake fluid over time will degrade and effect how your car stops to rest. The problem with brake fluid is that it’s hygroscopic; it absorbs moisture from the air. The more moisture brake fluid absorbs, the more prone it is to overheating and fading. The older the fluid is, the less effective it will become.
Another problem with moisture is that it corrodes the calipers, wheel cylinders, brake lines, and everything else revolving around it, working from the inside out. Old, moist brake fluid can lead to seized calipers or brake lines rusting out from inside.
Fluid can get too hot and boil. This can also happen if a caliper hangs up or seizes, rubbing on the disc while you drive overheating has a lasting effect on the fluid’s viscosity and effectiveness. If the fluid in the master cylinder smells burned, or is exceptionally dark in color, it’s time to change it.
When Do I Change My Car’s Brake Fluid?
Because it is regularly called upon to work at high temperatures, your brake fluid will lose its effectiveness over time. Most car-makers suggest it is done as part of a major service, which is usually carried out every two years. For example, some car manufacturer recommends that the first brake fluid change is not needed until the car is three years old.
It is also important to note that brake fluid can be corrosive, so you should take care not to get it on your skin. It’s also a good idea to wear a pair of disposable gloves while you are doing the job.
But brake fluid deteriorates rapidly once it comes into contact with the air, because water vapour can cause rust in the system, but it also lowers your brake fluid’s boiling point. In cold weather, this can lead to ice crystals forming in it, which will eventually turn to water, and will reduce the effectiveness of your brakes. If your car is fitted with ABS, contaminated fluid can damage and even destroy important working parts of such systems thereby causing expenses for you.
Exposure to air swiftly contaminates brake fluid: The oxygen in the air oxidizes it and lowers its boiling point. Brake fluid also has an affinity for moisture, and the water vapor in the air can combine with the brake fluid, lowering its boiling point and, in cold weather, forming ice crystals that make braking difficult. Adding fluid contaminated with water vapor to your brake system can rust the system and create acids that etch your wheel cylinders and master cylinder and foul your brakes, causing them to work poorly or not at all. This can lead to ice crystals forming in it, which will eventually turn to water, and will reduce the effectiveness of your brakes. If your car is fitted with ABS, contaminated fluid can damage other expensive braking systems and even destroy important working parts of such systems thereby causing expenses for you.
How to Change Your Brake Fluid
The best way to tackle this is with the car up on jack stands, and all four wheels removed before you start.
Drain the old fluid – Take the cap off the brake master cylinder and, using a turkey baster or something similar, remove as much of the fluid as possible. Put this old fluid in a suitable container for disposal. Once you’ve removed as much as you can, get a lint-free cloth and clean out any debris that might be in the reservoir.
Fill it back up – Once that’s done, you need to fill the master cylinder back up with fresh, new fluid, right up to the MAX line. Make sure you use the correct-specification fluid which should be marked on the master cylinder cap. Don’t put the cap back on yet, because you’ll need to top it up a few times. You’re looking to push all the old fluid out with the clean, new fluid.
On to the calipers/cylinders – Each brake calliper or drum brake wheel cylinder has a bleed nipple on the back. Spray each with some brake clean to clean off the grease and grime, then penetrating oil to free it up.
Start with the furthest – For most cars, you start at the corner furthest from the master cylinder. That would be the rear wheel on the passenger side. Affix a small length of rubber hose to the bleed nipple, and then submerge the end of the hose into the container you put the old brake fluid from the master cylinder in.
Time for a helper – With your helper in the driver’s seat, go to the first bleed nipple. Stick a block under the brake pedal to stop it from being pushed to the floor, which is too far.
Read More: Symptoms of Blown Piston Ring
Pump and hold – Have them pump the brakes 3 times, and then hold the pedal down. While they hold the pedal, you loosen the bleed nipple and old fluid should quickly come out, along with any air in the line. Close the nipple and signal for your helper to pump the pedal again and hold it. Open and close the nipple again. Keep doing this until new fluid is coming through, without any bubbles.
Top ups – Keep an eye on the fluid level in the master cylinder, because you will need to top this up as you progress. If you let the master cylinder reservoir run empty, you will pump air into the lines and have to start over.
Rise and repeat – Do the same for each wheel, working closer to the master cylinder as you go.
One last thing – When you finish the last caliper, you should have a decent pedal ‘feel’, by which we mean the pedal should feel firm. This is good, because it means the brake system is full of new fluid and not air. Now check the level in the master cylinder one last time, top off if needed, then close it up.
Wheels on – With all four wheels off, this is also a great time to rotate the tires. Put the wheels back on, lower the car to the ground, and be on your way. This is indeed how you can meticulously change your brake fluid to avoid ineffectiveness of brake.
In the next article, we are going to write on ‘where is the break in the car.’
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