How to bleed your brakes
November 10, 2021 Topic: How To
How do brakes work?
Modern cars use a hydraulic brake system, which means they work by pushing pressurized fluid. When you press down on the brake, this creates pressure in the brake lines. This pressure is transferred to the brake calipers, which in turn press your brake pads against your disc to slow your car down with friction.
The one important aspect of this process is the pressurization of the fluid in your brake lines. The fluid in brake lines is incompressible, meaning when you apply pressure onto your brakes this same pressure is transmitted throughout the system. Once you start getting air or other contaminants in the system, you can lose your braking pressure, reducing your braking efficiency. You may notice you have to push your brakes down further and further to get the same stopping power.
Your brakes produce a tremendous amount of heat, and if you get moisture in your brake lines, the heat can cause this moisture to boil. This can cause you to lose pressure and your ability to stop. Moisture can also cause corrosion of the wheel cylinders or brake calipers and eventually lead to a leak.
What is bleeding your brakes?
Bleeding your brakes is the process of removing any air from your brake lines to ensure you maintain constant and reliable pressure when braking.
When do you need to bleed your brakes?
Now that you know how brakes work and the dangers of air or other contaminants in your brake line, what are signs that you need to bleed your brakes to remove these pockets of air?
Your brakes feel spongy and not firm.
This is one of the most common reasons to bleed your brakes. This is a clear sign that you’re losing pressure in your braking system, as you are having to push your brakes harder to get the same amount of pressure than before the air got into your system.
It takes longer than usual for your car to stop.
If your pressure is weaker than before, the brake pads will have less force when they press against your disc, causing your braking time to increase as the pressure decreases.
You brake too often or for long periods of time.
If you live in a mountainous area, this is very common when you are traveling often on downgrades. If you are braking for long periods of time, your brakes will heat up and potentially cause your brake fluid to boil, leading to bubbles forming in the system. This will reduce your braking power, which can only be fixed with a drain.
How to bleed brakes
Now that we have gone over how to know if you need to bleed your brakes, let’s look at how to actually do so.
1. Gather your necessary tools
Before we begin let’s make sure we have everything we need. You will need:
- A tool to open the bleed valve – usually an appropriate size wrench or line wrench is best for the job. The most common bleeder valve size is 10mm.
- A catch pan to collect the drained brake fluid.
- New brake fluid to replace the old. Check your owner manual for specifics.
- A vacuum pump
- A brake bleed kit
2. Locate the bleed valve
Car manufacturers and engineers know bleeding brakes is a common maintenance process, and thus have made it fairly simple.
All you need to do is find your bleed valve usually located on the bottom of the brake caliper assembly. If you can’t find it, your owner’s manual should have a guide, or a quick google search of your make and model will help you find your bleed valve fairly easily.
3. Bleeding brakes
If you want to bleed your brakes you will need a brake bleed kit and a hand held vacuum pump
- First remove the old fluid from the master cylinder until it’s almost empty. Refill the master cylinder with new clean fluid.
- Once you have your bleed kit, you will want to attach the plastic tube that comes with the kit to the rear right caliper. Bleed the caliper furthest away from the master cylinder.
- Next, you will want to push the brake pedal repeatedly. You will slowly start to see cleaner and cleaner brake fluid. Be sure to check the master cylinder level to keep it topped off. Once the fluid is coming out clean of the first caliper close the valve and move to the next wheel.
- You want to move from the rear right wheel to the rear left, then front right and finish at the front left wheel. You are bleeding each caliper in a row that is furthest from the master cylinder.
- After you get clean fluid at each wheel and you confirm your master cylinder fluid is clean. Step on the brake pedal repeatedly with the engine off to ensure the brake pedal is nice and firm. After that you are all set!
Dangers of replacing your brake fluid
While bleeding your brakes is a fairly simple process, we do have some words of warning before you start the process.
- Never work on your brakes after recently driving. Your brake fluid can get very hot, and it is very easy to burn yourself or have built-up pressure cause the fluid to squirt out causing serious burns.
- Find your leaks first. If there is a leak in your brake line, you will constantly have to bleed your brakes or refill your brake fluid. You need to fix any leaks before you bleed your brakes.
- Brake fluid can be carcinogenic. You will want to be sure to wear protective clothing and gear to prevent contact with your skin. Latex gloves and eye protection is recommended.
- Never reuse brake fluid. Brake fluid is easily contaminated by dust, air, and moisture. These can corrode your brake lines and lead to leaks.
- Don’t let your brake fluid come in contact with your brake pads or discs. These components of your braking system require friction to work effectively. Brake fluid acts as a lubricant and will drastically reduce your braking efficiency if it gets on either of these components.
- Use the correct brake fluid. There are a few different varieties of brake fluid depending on the make and model of your car, so be sure to check and use the correct one for your vehicle. These are usually found in your owner’s manual or can be found online.
Which brake fluid should you use?
There are four different types of DOT brake fluids to choose from, however, a higher number doesn’t mean a better product. Choose the DOT number recommended in your owner’s manual. These products have different boiling points. Some are synthetic, and some do not work with ABS systems, so it is best to follow the manufacturer’s recommendations here.
Brakes To Go is here to help!
If you’re in the Central Texas area and you think your brakes may have a leak or you want someone to check your system, Brakes to Go mobile brake repair is there whenever and wherever you need. We will come out and give you a free assessment to determine the root of your brake problems. Get a free quote today to fix all your brake issues with top quality and unmatched convenience.
Want to continue learning about brakes? Check out our post that informs you on what to do if your brakes fail while driving.