Given the COVID-19 pandemic, it has become essential to learn some car maintenance skills in order to ensure that your life functions smoothly and doesn’t run into hurdles that derail it. It has become increasingly important to maintain social distance, and given the various degrees of lockdowns imposed all over the world, it has become difficult to go mechanics or other services should the need ever arise. In this guide, the process of bleeding brakes has been detailed, starting with what exactly it entails and how to go about it with your vehicle at home.
Brakes need to be bled when the brake pads become thin, causing the brake pedal to feel spongy and low. In this case, the fluid level of the brakes drops heavily in the master cylinder reservoir, leading to the creation of a vacuum or air bubbles in the lines. Since air is a compressible element, it acts like a spring of sorts in the pathway between the brake fluid, your foot, and the wheels. You need to bleed your brakes in order to push out the air and make sure that your brakes function normally again.
Bleeding your brakes also requires you to switch the old fluid with a fresh one. This is because the old fluid has been contaminated. The composition is not pure anymore, due to wear and tear that comes with use. It contains dirt from the atmosphere and particles of metal due to abrasion and the movement of parts in both the calipers and the master cylinder. Also, the fluid absorbs moisture from the air leading to a decreased boiling point. This is low enough to make it boil over at the end of a long downhill grade. In addition, the brake fluid morphs from a clear fluid to one that resembles tar or black ink due to exposure to high temperatures from high energy dissipation stops.
Moreover, it is important to be aware that there is a difference in tolerance levels between antilock braking systems and non-antilock braking systems. The former is less tolerant of air vacuums and contamination than the latter. This is because, in antilock braking systems, the hydraulic pumps function at 1000 x psi, which pushes the brake fluid into tiny valves. The pressure created due to the forced motion can whip air and brake fluid together into a foamy texture, which makes the process of bleeding brakes much more complicated. In addition, due to the size of the valves and the pump, these can be damaged readily by small particles that are abrasive in nature.
While the air that has seeped into the antilock braking system can be bled out, however, in some cases, vehicles require you to use some expensive antilock braking system scanning tool for cycling the machinery in order to push out the lodged air. In this case, it is important to be mindful and prudent enough when utilizing the vehicle never to let any air enter the ecosystem of the car. The system can simply be flushed with fresh fluid using a limited set of tools – a wrench compatible with the bleeder bolts and an attentive enough companion.
The process of bleeding brakes is relatively simple. It just requires attention span and some basic tools. The first step is to start out by getting the car up in the air with all the wheels removed. However, it is possible to do this with the wheels on still, if you can manage to use the wrench and swing it on the bleeder valves. The bleeder valves need to be loosened. Use a wrench size that is compatible with a bleeder bolt and fits it snugly. In addition, to make the process completely seamless and smooth, you can use some oil, preferably a penetrating oil on the bolts to get them off quickly and easily. Moreover, some tapping with a hammer can help with getting rust and corrosion off, making the process even more seamless for you to handle. The bolts should be loosened but must be left closed.
In the event that you can’t get the bleeders without having to break them off completely, the calipers of the brake or the wheel cylinders will warrant a replacement. Hollow and smaller bolts must be treated with oil and the hammer technique before attempting to break them off.
Moving on, screw the top of the master cylinder reservoir off and remove the old brake oil efficiently. This next step can be done by using a syringe or a turkey baster to pull out the contaminated brake fluid and the additional sediment and abrasive materials. Then use a cloth that is clean and lint-free to clean any remaining sediment out of the main body. Be careful not to spill the fluid, as it erodes pain jobs.
Next, start out with a clear plastic tube, and push one end of it over the brake bleeder bolt located at the right rear end of the car. The other end of the tube must be placed in a can or a bottle with nearly 2 inches of fresh brake fluid. This is done to ensure that air vacuums aren’t created in the caliper or the cylinder. Next, use a spacer or some small lumber and put it under the pedal to make sure that the pedal doesn’t travel too far when the line pressure is let up. Next, start with a few 8 oz cans of crystal clear, new brake fluid. Make sure that the can is a fresh one, rather than an open one, as the open one can get contaminated and must be thrown out immediately. Unopened brake fluid cans last for a very long time, so if you have some leftover after, it shouldn’t be a concern.
Pour the fresh brake fluid into the master cylinder and place the lid back on the reservoir. The fluid bubbles out of the unlidded cylinder whenever the pedal is let up. Here, the helper comes in. The helper must follow your instructions word for word. The helper’s job is waiting in the driving seat for further instructions
The idea is to yell the word ‘down’ to the person helping, asking them to depress the brake pedal with robust force. Then, the helper indicates that they have applied pressure by saying down and maintaining the pressure on the pedal. When you hear them say so, tell the assistant when the brake pedal is due to go under, and tell them to maintain their hold on the accelerator. Following this, the bleeder bolt needs to be turned the quarter of the way through. This process must be repeated until fresh and clear brake liquid squirts from the bleeder.
If you mess up the sequence, air can be sucked into the caliper despite the tubing as air can be sucked in past the space on the bolts into the ecosystem of the car. With each iteration of the drill mentioned above, the reservoir must be topped off with fresh brake fluid. It must not be more than half empty at all times, as air vacuums can be created in the master cylinder when the fluid level drops below the halfway mark.
Following this, when the clear, fresh brake fluid flows out of the brake, the bleeder bolt must be tightened. The exact process is to be repeated on the left rear end wheel of the car. Then, the process must be taken up with the right front wheel, and finally the left front wheel. This is to be followed with a little more brake fluid from all four ends once more. Remember, the reservoir must be topped off at all times; otherwise, the exercise becomes null and void. The process is lengthy and may seem daunting at first, but once you get the hang of it, it becomes easier to handle.
Last but not least, the process works perfectly even for a vehicle that does not have an antilock braking system if there is still air in the ecosystem after getting a new caliper and the master cylinder.
Is it necessary to follow the order of bleeding sequence, as mentioned above?
Yes, in general, the method mentioned above of bleeding brakes is standard. It applies to nearly all vehicles. It is, however, fruitful to confirm it in line with your car.
Do I need to keep my engine off?
Yes! You must keep the engine off. The only pump needed is for ABS.
While the task at hand seems a bit odious and complicated to perform, it is a necessary skill to learn, especially during such a time in the world. This guide is extremely detailed in terms of what to do and outlines each step carefully. Follow the methods, refer to it over and over again, until you get the hang of the process and understand it fully. This way, your attempt can not go wrong.