Brake fluid is also known as hydraulic fluid. It is responsible for moving the different components of your car’s braking system.
Brake fluid operates under high temperatures and high pressure. Without brake fluid, your car wouldn’t slow down or come to a stop when you press down on the brake pedal.
What does brake fluid do?
Brake fluid is a lubricant and anti-corrosion fluid that ensures your brake system works optimally all the time. It’s non-compressible, which means it’s always in the brake line, ready to work and deliver force every time you push on the brake pedal. The hydraulic brake system works like this:
- The brake pedal is pressed
- The pedal pushes down a piston inside the brake caliper
- This process increases pressure inside the brake lines, pushing brake fluid throughout the system
- Pressure cause brake rotors to squeeze the brake pads into action
- Brake pads make contact with the wheels, slowing the vehicle down
- You stay safe by being able to control your vehicle, all by touching your foot to the brake pedal
That’s a lot of responsibility for one system! And it hopefully shows you just how important brake fluid is. It’s an essential component to ensure your vehicle operates.
What are the most common brake fluid problems?
Brake fluid isn’t like motor oil or windshield washer fluid. You don’t drive in and have it changed out on a regular basis. Still, brake fluid can develop problems over time.
The most common has been when moisture seeps into the brake fluid. However, with increased technology comes better construction. If you have an older car – 20 years or older – moisture in brake fluid was a problem. But with today’s components, seals are tighter than ever, which has eliminated most of the moisture intrusion issues.
Brake fluid usually contains up to 5 percent of additives. These are corrosion inhibitors added to prevent corrosion within the brake system. Brake fluid itself won’t corrode. What happens instead is when brake fluid no longer has anti-corrosive qualities, the internal brake hydraulic components may not get what they need. This is when breakdown occurs.
Brake fluid corrosion can occur:
- With excessive heating or overheating through usage of a car’s brakes
- By overusing the brake system with heavy loads or weight that exceeds recommendations
- With excessive stop and go driving, pouncing on the brakes
- By adding low-quality brake fluid
- Through temperature extremes
What happens if brake fluid is low?
Different car manufacturers have different requirements when it comes to filling up your brake fluid reservoir. Check with your owner’s manual to determine how frequently to change out your brake fluid.
In theory, it can be a DIY project. But you have to understand how the basic brake system works, and have specific information about how your car works. Pay attention to the brake bleeding procedure; it needs to be performed in the right manner to keep you safe.
Are there different types of brake fluid?
In general, brake fluid isn’t that fancy. But different cars experience different driving conditions, so there are several different kinds of brake fluids to meet all needs.
DOT 3 has a glycol-ether base. It is designed for regular vehicles with average driving patterns, such as commuting.
DOT 4 is similar to DOT 3, only with more additives to increase boiling points. You’ll find DOT 4 increases performance, or move to Super DOT 4 for even better performance. This fluid is often used for racing or performance vehicles that can greatly exceed normal speed limits.
DOT 5 is not compatible with any other brake fluid types. It’s a rust preventer, and unlike other brake fluids, it won’t harm paint if spilled. It’s also costly. Unless your vehicle was specifically designed with DOT 5, this isn’t an option for most cars.
DOT 5.1 is similar to DOT 3 and DOT 4 in composition, but acts more like DOT 5 on the road. It has a lower viscosity, which is necessary for some vehicles.
In technical terms, DOT 3, DOT 4, and DOT 5.1 are similar. In a pinch, you can substitute one for another. But you shouldn’t drive without the proper brake fluid for very long. FLush the entire system and add in fresh, clean brake fluid as recommended by your car’s manufacturer for best results.
DOT 5 cannot be substituted at any time. It could damage your brake system.
What is bleeding the brakes?
If you read anything about your brake system or adding brake fluid to your car, you’ve probably noticed talk about bleeding the brakes.
Bleeding the brakes is the process of pushing new brake fluid through the brake lines and removing the old. As brake fluid wears, it loses additives and has an increase in gas bubbles within the line. By draining the old fluid out, you ensure what’s left is high quality, fresh brake fluid ready to do its job.
This process requires a few tools. You’ll need a wrench to open up the valves located by each brake caliper. You’ll also need a catch container to hold the old brake fluid. You’ll also need a way to operate the brake pedal to push the new brake fluid through the system.
This process takes skill; don’t run the brake reservoir dry or open the valves too far. This can allow more bubbles into the system, which can cause serious safety issues as you drive. A professional will ensure the job is done right the first time.
What about a brake fluid flush?
The other term you’re likely to hear is brake fluid flush. The name makes it sound like the system is being flushed with cleaner to remove old brake fluid before new is installed. In reality, a brake fluid flush and bleeding the brakes are identical. It’s when new brake fluid is forced into the system, pushing the old fluid and all of its potential issues away. That’s it.
How long has it been since your brake fluid was changed?
Now that you know the importance of brake fluid to your car’s brake system, the next question is: when was the last time you had your brake fluid changed?
Your brakes are one of the most important systems to keep you safe as you drive each day. If you’ve noticed a change in the way your brakes work, it’s time to have them checked. We can help. Make an appointment, and one of our professional mechanics will evaluate your systems and make suggestions for the best way to proceed. We’ll get you back on the road in no time.