What is brake fluid, and why should it be important?
Brake fluid is a specific hydraulic fluid that applies pressure from your foot on the brake pedal to the brake pads or shoes at every wheel. When the brake pedal is pressed, the fluid travels through the brake lines to engage the brakes.
Without sufficient brake fluid or if the fluid is leaking, your car's braking system is unable to operate as it should. This results in soft brakes, a longer stopping distance, or a total loss of braking power.
Symptoms that your car is leaking brake fluid
Before examining the causes, it's good to know the symptoms of a brake fluid leak:
• Soft or spongy brake pedal: If the brake pedal sinks too far or feels soft, it could be due to low fluid.
• Brake warning light: Most modern cars have a dashboard warning light that comes on when brake fluid is low.
• Visible fluid puddles: Yellowish or clear fluid under the car, near the wheels or under the engine.
• Poor braking performance: Longer stopping distances or brakes not responding as usual.
• Burning odour close to wheels: Leaking brake fluid in a few instances makes contact with hot parts and causes an odour.
If you experience any of these symptoms, check your braking system immediately.
Causes of brake fluid leaks
Several factors can cause your vehicle to leak brake fluid. It is crucial to identify the source as soon as possible to ensure safety and prevent further harm.
1. Leaking brake lines
The brake lines contain fluid from the master cylinder to the brakes on every wheel. They can rust, crack, or create holes over time, particularly if you travel on wet or salty roads.
Symptoms:
• Fluid along the undercarriage
• Brake warning light on
• Soft pedal when braking
Repair:
• Rigorous replacement of broken brake lines
• Check the entire system for rust
• Install top-quality brake lines compatible with your car
2. Master cylinder failure
The master cylinder converts pressure from your brake pedal into hydraulic pressure. If the seals within the master cylinder leak or wear out, brake fluid will leak out, typically near the firewall in front of the hood.
Symptoms:
• Brake pedal drops slowly
• Warning light on the dashboard
• Fluid accumulates close to the pedal assembly
Fix:
• Renew the master cylinder
• Utilise the proper brake fluid approved by your car manufacturer
• Bleed the brakes following replacement to purge air
3. Worn brake callipers or wheel cylinders
Brake callipers (in disc brakes) and wheel cylinders (in drum brakes) apply the brake pads or shoes to the discs or drums. When the seals within these parts wear out, they leak brake fluid.
Symptoms:
• Fluid around the wheels
• Spongy or uneven braking or pulling to one side
• Soft pedal
Repair:
• Rebuild or replace callipers or wheel cylinders
• Replace pads or shoes in case of contamination with fluid
4. Loose or damaged hoses
Flexible rubber hoses link the brake lines to wheel cylinders or callipers. These hoses can crack, bulge, or deteriorate over time, potentially causing leaks.
Symptoms:
• Fluid leaking around the wheels
• Spongy brake pedal
• Warning light on
Repair:
• Replace old or damaged hoses
• Adequate fitting and torque of hose connections
5. Loose or damaged fittings
Brake fittings link the lines, hoses, master cylinder, and callipers. If a fitting is loose or damaged, fluid will leak.
Symptoms:
• Small puddle under the car
• Fluid spraying during braking (in extreme cases)
• Brake warning light
Repair:
• Tighten fittings to proper torque
• Replace damaged fittings at once
6. Overfilled brake fluid reservoir
Overfilling the brake fluid reservoir is rare but can lead to spilt fluid, particularly when the brakes become hot.
Symptoms:
• Fluid close to the reservoir under the bonnet
• Pedal normal but fluid levels decrease
Repair:
• Drain excess fluid to the proper level
• Top up after checking for other leaks
7. Degraded or contaminated brake fluid
Brake fluid will absorb moisture over time, losing its effectiveness and potentially causing corrosion in the braking system, which can lead to leaks.
Symptoms:
• Feeling of soft or spongy brakes
• Rust on brake components or lines
• The warning light appears
Solution:
• Flushing and replacing brake fluid every 2 years
• Applying the correct grade as specified by your car manufacturer
How to check for brake fluid leaks
Here are some tips to check for brake fluid leaks:
1. Visual inspection: Look under the car, around each wheel, and under the bonnet for wet spots or puddles.
2. Check the fluid level: Inspect the reservoir; if it’s low, there may be a leak.
3. Inspect brake lines and hoses: Look for cracks, corrosion, or loose fittings.
4. Check around callipers and wheel cylinders: Look for fluid on pads, shoes, or near wheel hubs.
5. Drive carefully: If you feel a soft pedal or reduced braking, stop and inspect immediately.
It is vital to note that you should never ignore a leak, even a small one can lead to dangerous braking failure.
Risks of driving with leaking brake fluid
Driving with a brake fluid leak is extremely dangerous. Some of the risks include:
• Brake failure: You may lose the ability to stop effectively.
• Longer stopping distances: Even partial leaks reduce braking power.
• Uneven braking: The car may pull to one side during braking.
• Damage to brake components: Fluid leaks can ruin pads, discs, or callipers.
• Safety risk: Both for you and other road users
If you notice any signs of leaking brake fluid, stop driving immediately and get the car inspected. Brake fluid leaks can seriously reduce braking power. Our ACKO Drive service centres locate and fix leaks from hoses, cylinders, or callipers. We then refill and test the system for complete safety. You can book a service slot online through the ACKO app or the ACKO Drive website, and we will take care of the rest. From vehicle pickup to detailed diagnosis, we offer high-quality car services using original spare parts.
How to fix a brake fluid leak
The repair depends on the location of the leak. A mechanic will usually follow these steps:
1. Locate the source of the leak – master cylinder, callipers, hoses, or lines.
2. Replace faulty parts – hoses, callipers, cylinders, or the master cylinder.
3. Bleed the brakes – remove air from the hydraulic system to restore proper braking.
4. Refill with correct brake fluid – never mix different types.
5. Check the system for other leaks – ensure no other weak points exist.
Always use genuine or high-quality replacement parts for safety and durability.
How to prevent brake fluid leaks
Preventing brake fluid leaks is mostly about regular maintenance and inspections:
• Check fluid levels every month and top up if necessary.
• Replace brake fluid every 2 years or as recommended by the manufacturer.
• Inspect hoses, lines, and fittings during each service.
• Replace worn brake pads and shoes promptly.
• Avoid harsh driving that overheats the braking system.
• Ensure repairs are performed using genuine or high-quality parts.
Regular care keeps your brakes functioning safely and prevents unexpected failures.
Final words
A brake fluid leak is a serious safety issue that should never be ignored. Whether it comes from the master cylinder, callipers, hoses, or lines, it can reduce braking performance and lead to accidents.
If you notice low brake fluid, a soft pedal, or fluid under your vehicle, have it inspected by a professional mechanic immediately. Early detection and repair will ensure your braking system stays reliable, safe, and efficient.
Frequently asked questions
