Home Diagnosis and TroubleshootingBraking System Brake Fluid Leak – How To Find It And Fix It?

Brake Fluid Leak – How To Find It And Fix It?

by Jordan Harris
Brake Fluid Leak

Are you having problems with your brakes? You probably suspect a brake fluid leak. If this is the case, then you are at the right place because there will be a lot to cover on this topic where we will learn everything when it comes to this problem.

Having a brake leak is a serious matter. Why I’m saying this? Well, it’s really simple. Brakes make you stop your vehicle. If there are no brakes around, you will not be able to stop your car at the right time and will possibly end up in an accident. Or you will notice some other symptoms like a soft brake pedal and uneven brake pad wear. All, this indicates a possible leak. But more on the symptoms later in the article.

What is important for you right now is to put your sleeves up and start troubleshooting the matter. You need to learn how to troubleshoot the issue and learn how to solve it. And by this, we mean that you need to learn how this braking system works and from what components it is made out of. Knowing this stuff will help you connect the dots really fast. And we are going to help you out with this by explaining it in detail.

Then we will also cover the possible causes for this problem to happen and also the symptoms of the brake fluid leak. After this, we will jump into diagnosing and fixing the matter. So, if you want to learn more about sorting this problem out as quickly as possible, follow along.

What Is A Brake Fluid Leak?

Now before we dive into the causes and symptoms of a brake fluid leak, let’s cover some of the basics. And that is what is a brake fluid leak in general. This will be quite a useful introductory chapter for the ones who are not familiar with the matter and want to learn more about this problem in general. If you want to learn the causes and symptoms, move on to the following chapters. If not, keep up with us.

So, what is a brake fluid leak? Well, a brake fluid leak is a situation where you lose brake fluid. Losing fluid is dangerous and could cause your brake system to malfunction and develop issues. Most notably you will experience problems while pressing the brake pedal. These problems will be represented through the lack of response of the system.

As you know the brake fluid is a hydraulic fluid that keeps the right pressure in the system. And this pressure basically makes the brake system work properly as it should. If there is a lack of fluid there will be problems since air will get inside of the brake lines. When the air gets inside the brake lines, you will experience issues. Since air can be compressed when you press the brake pedal, unlike the hydraulic fluid. And this will result in a squishy brake pedal.

Not to mention that your vehicle will constantly be losing brake fluid and this fluid needs to be topped off all the time if you don’t want your brakes to fail completely and you end up in an accident. So, whenever you notice a brake fluid leak and some of the symptoms that we are going to discuss later on, it is advisable for you to take some action.

How The Brake System Works

Now before we cover the causes of brake fluid leak, let’s learn how the brake system works in practice. What is a brake system in general? Well, the brake system in your car is the one that makes your vehicle stop. Without it, you will not be able to stop the car.

This is a hydraulic system. Meaning that the brake system works with the aid of hydraulic fluid. The hydraulic fluid is quite an essential thing when it comes to the proper operation of the brakes. Without it, you will not come to a stop.

This fluid is often branded as DOT. There are a variety of brake fluids like DOT 3, DOT 4, and DOT 5. The choice of the fluid varies greatly on the application and the car manufacturer. For the exact fluid for your brakes, you should consult with your driver’s manual that comes with the car.

Nevertheless, this system is simple when it comes to operation. The brain of this system is the master cylinder that is mounted on the firewall. In this master cylinder, there are pistons that move. When you apply on the brakes these pistons move and transfer the fluid through the brake lines.

Then this hydraulic pressure that is built in the lines is transferred to the brake calipers. And as you know, on each caliper there are pistons that open and close when you press and release the brakes. These pistons basically apply pressure on the brake pads and make the car stop. Then they retract after the brake pedal is released and make the car move again.

It’s a simple process. But sometimes event this system can fail. Sometimes caused by brake fluid leak, sometimes because of other things. But what could possibly cause the brake fluid to leak? Let’s elaborate on that next.

Brake Fluid Leak Causes

Now as we learned what is the problem with the brake fluid leak, now let’s learn more about the causes for this leak. What could be the causes that can make leaks develop? Let’s elaborate on them in the following chapters and later we will also cover the symptoms that are associated with this problem.

1. Leaky Master Cylinder

The first probable cause for brake fluid leak is the failing master cylinder. As we already told you, the master cylinder is the brain of the braking system and this master cylinder regulates the pressure of the hydraulic fluid.

With this master cylinder, you basically are able to stop the car. Unfortunately, though, there are a lot of rubber fittings inside of this master cylinder that can develop leaks.

The rubber simply deteriorates after long years of use and the master cylinder starts to leak. These leaks are visible to the naked eye. You will probably notice some grease spots around the master cylinder if it is leaking and releasing brake fluid.

It is advised to inspect it thoroughly and see its condition and determine if the master cylinder is leaking. If it is, then it will need to be replaced as soon as possible. Now let’s discuss the next probable cause for brake fluid leak.

2. Leaky Brake Fluid Lines And Fittings

Another very common cause for brake fluid leak is the brake lines and fittings. Especially the fittings who are often not even painted and can develop rust around them.

So, if you live in a state where there is a lot of salt thrown on the streets during the winter, you can expect these fittings to rust a lot and eventually fail. This failure of the fitting will develop a brake fluid leak and air will get into the system. Resulting in poor braking of your car.

That’s why it is often advised to check all of the lines and fittings if they have failed if you want to determine that there is a brake fluid leak. Now let’s move to the last probable cause for this problem happening.

3. Broken Caliper

The last cause that we want to address is a broken brake caliper. The caliper itself is a big metal piece. But what can break are the seals of the pistons that are mounted on the caliper.

The seals that are on the pistons can leak and cause your caliper to stick as well as develop leaks around it. So, you probably want to address this issue as soon as possible.

If you have sticky brakes and seized brake caliper. You are also highly likely are having an issue with the caliper itself. The caliper in this case needs either to be refurbished or replaced completely. It is often advised to replace it because a rebuild kit will not do the job as a completely new brake caliper. Now let’s focus on the brake fluid leak symptoms in the following chapters.

Brake Fluid Leak Symptoms

Now let’s discuss the brake fluid leak symptoms. Knowing the symptoms is often advised because by knowing them, you will be able to tell if you have this problem or not.

Some of the symptoms are a dead giveaway, while some are a little bit more complex and will require deeper diagnosing the matter in order for you to be able to uncover the problem. So, what are these symptoms of brake fluid leak? Let’s elaborate.

1. Brake Light On

The first and most obvious symptom that you will notice will probably be the brake light on. This brake light often turns on whenever there is a problem with the braking system.

Whenever there are leaks, there is a sensor that measures the level of hydraulic fluid in the master cylinder. So, if this sensor gets some bad readings, you will highly likely face a brake light symptom on the dash.

You cannot know at once if you have a leak by looking at the brake light on the dash. But if you open the canister for brake fluid and there is not enough of it inside, you will instantly know that you have a possible leak.

That’s why whenever you have a brake fluid leak, it is advised to check the canister and top off the fluid. And also, address the brake fluid leak once you are able to do so.

2. Squishy Brake Pedal

Another symptom of a brake fluid leak is the squishy brake pedal. Some people also call it spongy brake pedal. Because the pedal is so soft like a sponge. Instead of being hard and with a small effort by your side you are to be able to come to a stop. With the squishy brake pedal, you will need to press harder for the car to come to a stop.

But why is this happening? What the brake pedal has to do with the brake fluid leak? Well, it has a lot to do with it. This is the case because there is air in your braking system.

Yup, that’s right, there are leaks and these leaks allow air to get into the system. So, when you press the pedal this air is compressed. That’s why there is a spongy feel to the brake pedal.

This symptom is a dead giveaway that there is the air that enters the brake system and this air is ruining the brake performance. When you notice this problem, you need to act immediately and sort out your brake fluid leak.

3. Low Fluid In The Master Cylinder

Another symptom of a brake fluid leak is the low brake fluid in the brake fluid reservoir. This reservoir is usually mounted on top of the master cylinder and this reservoir keeps the excess fluid.

Whenever there is a brake fluid leak in your system, the fluid inside of this canister will get empty pretty quickly. And as soon as it gets empty, there will be air sucked in inside of the master cylinder and this air as we explained above, will make the braking ability much worse.

Brake Fluid Leak

The brake pedal will start to feel soft and you might suffer from other symptoms of brake fluid leak that we are covering in this article. But more on the other symptoms in the following chapters.

4. Uneven Brake Pad Wear

When it comes to brake fluid leaks, uneven brake pad wear is also present. Have you noticed that the pads on one side of the car are quite more worn out compared to the ones on the opposite side? Why is this happening?

Well, this is happening because one of the circuits of your brake system has a leak. If you didn’t know, the master cylinder has two circuits. One circuit per each side of your vehicle. Meaning that one circuit controls the left side and one circuit controls the right side.

This is specifically created in order to prevent a complete failure of the brake system. Even if one circuit fails, the other circuit will work and will make the car stop.

But this also has some risks as well. Namely, the wear and tear of the pads on one side will be much more significant than the other. This is the cause because the pads on the side that have properly functioning brakes are working much harder to make your car stop.

More work means that the pads will wear off significantly only after a few thousand miles of driving like this. That’s why if you notice how on one of the sides there is a lot of pad wear material on the rims, this means that you need to take some action and make sure that you sort out this problem as soon as possible. Make sure that you sort out the brake fluid leak and drive safely.

5. Car Pulls To The Side When Braking

Another symptom of brake fluid leak that often occurs with the uneven brake pad wear is the situation when the car is pulling on one side when the car is braking. So, why is this the case? Why does the car pull on one side?

Well, the answer is really simple, the car pulls on one side because only the brakes on one of the sides are working. This situation will be most present under really hard braking. And because of this, it can involve you in potentially dangerous situations that could even cost your life. That’s why you need to diagnose the brake fluid leak if you want to avoid some unwanted events from happening. Later in the article, we are going to explain to you precisely that.

6. Poor Stopping Power

And the last symptom of a brake fluid leak that we are going to cover is an increased stopping distance. If you have low brake fluid in your car, then you also highly likely will be having problems with the stopping.

The car will not stop as it did before when the brakes were running as they should from the factory. This poor stopping distance will greatly increase the risk of you hitting another car on the road.

If you notice that your brakes are not up to the task and are not performing right, then you might consider that one of the consequences is a brake fluid leak. But how you can diagnose a brake fluid leak? Let’s elaborate more on that in the following chapters.

How To Diagnose Brake Fluid Leaks?

Now let’s discuss how you can diagnose a brake fluid leak. How you can really tell if you have a leak in your braking system? Let’s elaborate more in-depth on this topic.

Diagnosing a brake fluid leak is a relatively easy thing to perform on your vehicle. Why I’m saying this? Well, I’m saying this because this is really a beginner-friendly job. So, how this problem is diagnosed?

Well, the first thing you need to check is your brake pedal. If the brake pedal is spongy and has a lot of play from the time you press the pedal until the car starts to stop, then this is a clear sign that you need to take things further and check the master cylinder.

The master cylinder is a device that is mounted on the firewall. This device is basically holding the brake fluid. Take a peek inside and see the level and also the condition of the fluid. If the level of the fluid is relatively low, then you obviously have a brake fluid leak.

Also, inspect the master cylinder itself and see if there is something greasy on the sides. If there is something greasy covered with dust then this means that the master cylinder is leaking. If not, move to the brake lines and inspect where they go.

Check the fittings and see if there are leaks on some of the fittings. If there are leaks on a certain fitting, then you found your problem. If not keep looking. The next place you want to look for is probably behind the caliper where the brake line is connected to the caliper. These are notorious for developing leaks.

How To Fix The Leaks?

So, how you can fix the brake fluid leak? This really depends on what is causing the leak in the first place.

If the leak is caused by the master cylinder, you will have to replace this master cylinder with a new one. If the brake line is leaking then the line will be needed to be replaced. Similar to the calipers.

The pistons on the calipers tend to leak and cause problems. You will need to either rebuild the caliper or replace it.

Cost To Fix The Brake Fluid Leaks

The cost to fix the brake fluid leak also depends much on the leak cause. If the master cylinder is broken, you can expect to pay somewhere between $250 and $600 to replace it, depending on the vehicle of course.

Simple metal fittings are really cheap and can cost a couple of dollars to purchase. New brake lines are custom made and could cost you a few hundred dollars for new brake lines on all of the wheels.

Brake Fluid Leak

A brake caliper on average costs about $150. But this price can go up to $600 if it’s some really expensive vehicle. Overall, these are the costs of fixing a brake fluid leak.

How to Fix a Brake Fluid Leak – 10 Need-to-Know Facts

  1. Symptoms of a brake fluid leak include a brake light coming on, reduced brake responsiveness, sinking brake pedal, and a puddle of fluid beneath the car.
  2. The first step in repairing a brake fluid leak is to diagnose its placement and severity.
  3. The brake fluid reservoir is located on the driver’s side towards the rear of the engine compartment, and low fluid levels may indicate a leak.
  4. To locate the general placement of the leak, check beneath the car for the presence of brake fluid and place newspapers beneath the leak to identify the location.
  5. Crawling underneath the car and looking for the spot where fluid is dripping from the brakes can help determine the location of the leak, and removing the wheel may be necessary to check for leaks in the lines and calipers.
  6. The master cylinder should also be checked for leaks, and the master cylinder lid should be tightly closed to prevent leaks.
  7. Calipers, wheel cylinders, and the master cylinder can be rebuilt using a rebuild kit, but it is usually better to buy a new caliper than to attempt to rebuild one.
  8. To rebuild a caliper, remove the old caliper, piston, and outer dust seal, then replace the piston and caliper, and bleed all air from the brake system.
  9. To replace a wheel cylinder, remove the wheel and hubcap, and disconnect the brake line from the caliper before removing the old wheel cylinder and replacing it with a new unit.
  10. Bleeding air from the brake system is necessary after any brake system repair, and it involves removing all brake fluid from the master cylinder and replacing it with new fluid, then bleeding each brake one at a time.

Conclusion To Brake Fluid Leak

In this article, we have covered quite a bit when it comes to the brake fluid leak. First, we learned more about this problem when the brake fluid leaks. Then we learned how the brake system works and from which components it consists.

After this, we covered the brake fluid leak causes as well as the brake fluid leak symptoms. We learned all the possible scenarios. The most probable causes are the bad fittings of the brake lines or a broken brake caliper, while the most probable symptoms are a squishy brake pedal caused by the air that entered into the system.

Lastly, we learned how you can diagnose the problem and the cost to fix the issue depending on the root cause.

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