The braking system consists of several components. These components include brake pads, brake shoes, brake drums, brake master, brake booster, ABS, brake calipers, and brake lines. These components have to work in harmony to bring your car to a complete stop when you depress the brake pedal.
But without the brake fluid, all these components won’t actualize their single aim of bringing the vehicle to a complete halt. This is why you need to be cautious of brake fluid leaks and fix them before they cause severe damage to other system components. In this article, we’ll discuss in detail the color, signs, causes, and how to fix a brake fluid leak.
What causes brake fluid leak?
Before discussing the causes, what are brake fluid leak symptoms that you should watch out for? Several red flags indicate brake fluid leaks. Here are the signs you should watch out for when you suspect a brake fluid leak;
- Brake fluid is dripping under your vehicle
- Mushy or spongy brake feel when you depress the brake pedal
- The brake pedal goes to the floor when you step on it
- A brake warning light appears on the instrument cluster
We’ve outlined the common causes of brake fluid below. When you have a brake fluid leak, consider checking these components first.
Defective piston seal: Several brake components feature pistons in them, and these pistons come with seals. Brake components that feature pistons include the drum brake wheel cylinder, the disc brake caliper, and the brake master cylinder.
The piston is a moving part that functions with hydraulic force. It has seals that prevent the fluid from leaking. Over time, these seals will wear or be subjected to mechanical forces, allowing the fluid to leak.
Damaged brake hoses or brake lines: Brake hoses and lines are made from strong materials to withstand rugged roads and extreme conditions. Over time, they can pit, rust, or tear. Defective brake line fittings, broken brake lines, and torn brake hoses can result in fluid leaks.
Loosen or damaged bleeder valve: Each wheel on a vehicle has a bleeder valve, also known as a bleeder screw, used to bleed air from the brake system. If the bleeder valve becomes loose or rusted, it can cause fluid leaks.
Worn-out brake shoes, pads, drums, and rotors: Brake shoes, pads, drums, and rotors are subject to wear.
If these components wear out, it can cause the pistons to protrude beyond their intended position. This will damage the seal and cause fluid leaks.
Defective brake master cylinder reservoir: Most brake fluid reservoirs in newer cars are made of plastic and can become brittle from excess heat in the engine bay. If this happens, the reservoir will apparently crack, allowing brake fluid to drip out and flow down through the rear of the engine.
If you notice brake fluid leaking under the middle of the car, check the brake master reservoir for cracks or fluid around it. The brake lines can also be a culprit.
Lousy ABS Module: The module consists of high-pressure brake fluid lines. Unfortunately, this component can rust or wear down under mechanical force, leading to fluid leaks.
Where does brake fluid usually leak from?
If you’re experiencing any signs of brake fluid leaks, the first step is to check your brake system to confirm whether there’s a leak somewhere on the car. Start by opening the hood. Check the brake fluid level to verify if the system is leaking.
A severe leak will drastically reduce the fluid level. If you can’t locate the brake fluid reservoir, consult your owner’s manual. If the inspection confirms the fluid level is okay, there’s a chance you have a small leak that could be allowing air into the system.
Check the following areas for fluid leaks;
- Brake lines and hoses
- Brake master cylinder
- Front and rear calipers
- Drum brake wheel cylinder (brake pot)
If you have found leaks in any of these areas, I will walk you through how to fix them, step by step and practically. Do not skim through; follow the steps below religiously.
How do you fix a brake fluid leak?
The first step in fixing a brake fluid leak is identifying the source of the leak. Once you have identified the real source of the leak and its severity, the next step is to get it fixed and continue your daily commute.
Now, I will assume you have figured out where the fluid is coming from. Let’s face it and fix it.
This walkthrough covers only rebuilding the brake caliper, changing brake hoses and lines, replacing the brake master cylinder, and generally bleeding.
Method 1 out of 5: Rebuilding brake calipers
Nowadays, mechanics don’t rebuild brake calipers. Instead, they take it to a rebuilding station for a complete rebuild, and once the work is done, they reinstall the caliper. I recommend getting a new caliper rather than rebuilding the old one. The difference between a rebuilt and a new one isn’t much. If you choose to go for a rebuild and save those pennies, follow these steps.
Step 1: Detach the old caliper
- Get a rebuild kit from your dealership or a nearby auto store
- Loosen the bleeder screw bolt. If it’s proving stubborn, apply penetrating oil to avoid breaking it or having it worn.
- Detach the brake lines. Inspect the pipes and replace them if they are worn or cracked before reinstalling the caliper
- Detach the slider pins, springs, shims, and pads from the caliper
- Take off the caliper dust cover
- Insert a piece of wood that is slightly bigger than the brake pads in the caliper against the piston
- Send in compressed air into the caliper’s inlet port to push out the piston
Step 2: Reinstall the pistons
- Oil the new piston you want to install with transmission fluid or any light oil
- Insert the piston into the caliper and push it in. Do not forget the dust cover
Step 3: Reinstall the Caliper
- Fix the dust cover
- Reinstall the slider pins, shims, pads, and springs with the new ones from the rebuild kit
- Reinstall the brake lines
- Reinstall the bleeder bolt
- Cross-check your work and test it to ensure you have stopped the leak
- Remove the air in the system by bleeding it.
Method 2 of 5: Rebuilding brake hoses and lines
If the brake fluid is leaking from the hose or lines, there’s no quick fix. Go ahead and fix it. And if the brake fluid is leaking from the rear wheel, inspect it closely. There’s a chance the leak is from the brake lines, not the wheel cylinder.
- Raise the vehicle and support it with a Jack stand. Remove the tire
- Disconnect the brake line from the master cylinder or any fittings nearest to it
- Locate and remove all mounting clips/brackets holding the brake line
- Detach the defective line from the caliper
- Install the new line on the caliper. So not torque it yet.
- Reconnect the mounting brackets/clips on the new brake line
- Reconnect the other end of the brake line to where you removed it earlier
- Cross-check your work and tighten every single component
- Remove the trapped-in air from the system by bleeding it.
Method 3: Replacing a wheel cylinder
A defective brake wheel cylinder is much easier to replace, and it’ll give you more peace of mind than rebuilding it. A new wheel cylinder is almost identical to a rebuilt one.
Step 1: Take off the wheel
- Take off the wheel hubcaps.
- Lift the affected wheel off the ground and support it with a jack stand
- Unfasten the lug nuts and remove the tires
- Apply penetrating oil on the brake line fittings so you can easily break them free.
Step 2: Take off the wheel drum
- Remove the dust cover on the backing plate.
- Reduce the drum brake adjustment with a flat-head screwdriver
- Hit the center of the wheel drum with a hammer to break it loose from the rust
- Pull off the wheel drum
- Disassemble the brake components. Consider getting new brake shoes if they are soaked with brake fluid
- Clean the drum surface of dirt and fluid with brake cleaner.
Step 3: Uninstall the brake line
- Trace the brake line to where it joins with the wheel drum brake fittings, and loosen it with a line wrench
- Take off the brake fitting.
- Prepare and place a vacuum hose on the brake firing to stop the fluid from leaking.
Step 4: Replace the brake pot
- Find the bolts holding the wheel cylinder in place and uninstall them
- Take off the defective wheel cylinder
- Remove the vacuum hose from the brake line and thread it into the new brake pot by hand
- Fix the new pot as you removed the old one
- Expel trapped air from the system by bleeding it.
Method 4 of 5: Replacing the brake master cylinder
Newer brake systems have two circuits. Each circuit has two wheels, so if one circuit fails, the other will keep the brake system operational. The brake master provides hydraulic pressure to both circuits. So, if the brake master fails, it’ll affect all other brake components.
Getting a new one is much more accessible and affordable. If there’s a brake fluid leak on the master cylinder, it’ll affect both circuits and leave you with a flat brake pedal. Replacing it involves the following steps;
- Raise the hood and find the brake master
- Take off the fluid reservoir cover
- Drain the fluid with a turkey baster. Recycle the drained fluid in a safe can.
- Unplug the electrical harness
- Loosen the brake lines with a line wrench
- Unbolt the nuts holding the brake master in place
- Take off the old brake master
- Install the new unit
- Fix the brake lines using the reverse process
- Plug in the electrical harness
- Remove the trapped air by blessing the system
Method 5: Bleed the brake lines
Always bleed your brake system after any repairs to the brake lines. Brake bleeding requires assistance.
- Ask your assistant to pump the brake pedal
- Ask him/her to hold the pedal down while you lose the bleeder valve on the wheel cylinder or brake caliper. You have to bleed the wheels one at a time, keeping air out of the system.
- Catch the brake fluid with a container; do not let it touch your paint. Brake fluid is corrosive to paints and wax.
- Lock the bleeder valve and ask your assistant to pump the brake pedal a couple of times. Repeat the bleeding two or more times.
- Repeat the process on all wheels.
- Refill the brake fluid reservoir
- Test the brake system to ensure it works smoothly.
If you change any component on one wheel, always change the same component on the other wheel.
FAQs
Q: How much does it cost to fix a brake fluid leak?
Several factors affect the cost of repairing a brake fluid leak, including your car’s make and model, the extent of the leak, and your location. Fixing a brake fluid leak can be relatively cheap. It won’t break your budget. Here’s an estimated brake fluid leak repair cost.
| TYPES OF LEAK | REPAIR COST | |
| WHEEL DRUM CYLINDER LEAKS | ||
| Repairs (One wheel) | Parts $10 – 20 | |
| Labor $80 – 100 | ||
| Replace | Parts $25 – 40 | |
| Labor $40-70 | ||
| BRAKE CALIPER LEAKS | ||
| Repair (one wheel) | Parts $70 – 150 | |
| Labor $50-100 | ||
| Replace (one wheel) | Parts $100 – 200 | |
| Labor $30 – 50 | ||
| BRAKE MASTER CYLINDER LEAKS | ||
| Repair | Parts $80 – 200 | |
| Labor $50 – 120 | ||
| Replace | Parts $150 – 300 | |
| Labor $30 – 70 | ||
| BRAKE LINES OR BRAKE HOSES | ||
| Repair | Parts $10 – 40 | |
| Labor $30 – 50 |
If you’re a petrolhead and understand how the brake system works, you can fix the brake leak yourself. For everyone else, the best thing to do is consult your mechanic or dealership. Brake repairs are not a system fix you should play with. Your life and that of the passengers lie on it.
Q: Can you drive with a brake fluid leak?
Most brake systems in vehicles today work with hydraulic principles – they are activated with hydraulic force. So, it needs adequate brake fluid to provide peak performance. While you can drive a car without brake fluid, it is imperative to note that;
- You are causing damage to other system components.
- Your brakes will not hold. That is, a high chance of getting a crash
- If you are caught driving without brake fluid on purpose, you’ll be issued a ticket.
Brake fluid is the most affordable part of the brake system – yet essential. Low or brake fluid leaks are the common cause of brake damage and collisions. Hence, do not drive your car without brake fluid.
Q: How serious is a brake fluid leak?
As explained earlier, brakes operate under hydraulic pressure. Brake fluid helps carry out the driver’s demands as he steps on the brake pedal. If a brake fluid leak occurs, the brake system will lose the hydraulic pressure needed to function optimally, leaving you unable to stop your car.
Q: Can brake fluid go low without a leak?
Absolutely yes. When the brake pads and shoes wear out, the system will send the hydraulic fluid into the caliper or wheel cylinder. As a result, the brake fluid in the reservoir will reduce. That said, do not confuse this situation with a fluid leak. The moment you replace the worn-out brake pads and shoes, the fluid will return to the reservoir.
Q: Is it safe to drive a car without brake fluid?
While brake fluid won’t stop your car from moving, your brakes will not hold without it. In simple terms, no fluid, no brake. Driving without brake fluid is totally unsafe because your brakes will not hold. Do you know what that means? You’re preparing for a crash!
Final word
At this point, you have seen the causes, symptoms, and how to diagnose and fix brake fluid leaks. Aside from the general causes, there’s a particular cause that affects only a specific environment.
For example, if you live on the coast with a lot of salt in the air or drive in salty areas, you may have rusted and damaged brake lines more often.
Lastly, because some brake jobs are more accessible to fix than others, and parts replacement costs vary, it will be difficult to estimate the actual cost of repairing a brake leak.
