Brake fluids are the important hydraulic fluids that ensure the smooth performance of your car’s brake system. This fluid acts like a lubricant and prevents the internal parts of the braking system from corroding.
It is always recommended to note the color and level of the brake fluid, as it may become low and dirty with time. When the brake fluid becomes low or dirty, it produces different signs. This article explains the low brake fluid symptoms, causes, and how to change it.
What is Brake Fluid?
The brake fluid is a hydraulic fluid used in the brake system of your vehicle that transfers the force from the brake pedal to the brake shoes or pads. These pads are installed on the wheels of the vehicle.
The pressurized brake fluid activates the brakes of your vehicle. As the force is applied to the brake pedals, this force from the pedals is transferred to the calipers through brake fluid. When the brake calipers receive force, they further put pressure on the brake shoes or pads to stop or lower the speed of the car.
The silicone-based or glycol-ether brake fluids are the most commonly used fluids, but some mineral-based fluids are also present on the market.
The brake fluids have high boiling points just to avoid vaporization in the brake system. The vaporization in the brake system can be the reason for the loss of brake pressure, resulting in the reduction of stopping power.
It is always recommended to use the correct type of brake fluid as per the vehicle manufacturer’s instructions. The chemical properties of different fluids vary, and they differently influence the longevity of the brake system.
Symptoms of Low Brake Fluid
When the brake fluid becomes low than a specific limit, your vehicle’s braking system may produce one or more of the below-given symptoms:
- Soft or spongy brake pedals
- Increased stopping distance
- Squeaking noise
- Illuminated brake warning light
- Brake fluid puddles
- Dirty brake fluid
- Vehicle vibration
1) Soft or Spongy Brake Pedals
The soft or spongy brake pedal is one of the clear symptoms of low brake fluid. When the brake fluid is not changed for a long time, this fluid starts to boil right after applying the brakes. With this, the boiling fluid produces air bubbles in the system, and air cannot be compressed.
The air then makes the brake pedal soft, and you have to exert some additional push to stop your vehicle. To fix this issue, drain the old brake fluid and add the new fluid.
2) Increased Stopping Distance
The worn brake pads also indicate low brake fluid. With the worn-out pads, the brake piston needs to travel some extra distance to stop the car. To cover the extra distance, the piston consumes more fluid which results in a low fluid level. In such conditions, your braking system takes more stopping time than usual.
3) Squeaking Noise
A squeaking or squealing sound coming from the brake system is one of the clear symptoms of low brake fluid. If the squeaking sound is coming from the brake pads, it means your brake pads are worn-out.
The damaged or worn pads may lead to a quick reduction in the brake fluid level. Because in the case of worn-out pads, the piston of the caliper covers an extended distance from its housing to make contact with the brake pad.
In such a situation, the brake fluid works harder, and its boiling point increases due to an increase in temperature. Therefore, as you replace the brake pads, ensure to drain out the old fluid and refill it with fresh fluid. When the hydraulic system is opened, there are chances of increased contamination in the system. Properly clean the system to gain its best performance.
4) Illuminated Brake Warning Light
There is a brake fluid level sensor present in most cars near the fluid reservoir. When the brake fluid becomes lower than a specific level, the red brake warning light appears on the dashboard of your vehicle.
Some vehicle models also have a pressure differential valve and switch that inform about the pressure loss when it becomes low in the brake fluid circuit. As this switch closes, the brake warning light starts illuminating on the vehicle dashboard.
5) Brake Fluid Puddles
If there are fluid puddles underneath your car or you notice fluid leaking from the brake cylinders or lines, it may be a symptom of low brake fluid.
6) Dirty Brake Fluid
If the reservoir fluid is brown or black in color, it means that your fluid is dirty and old. The low brake fluid light appears on the vehicle’s dash whenever there is a need to replace the fluid.
7) Vehicle Vibration
A vibrating and rumbling vehicle also represents low brake fluid levels in the braking system of your car.
Read More: Low Power Steering Fluid Symptoms and Causes
Causes Of Low Brake Fluid
The brake fluid of your braking system becomes low due to one or more of the following causes:
- Normal Wear and Tear
- Leaks
- Overheating
- Wrong Fluid Type
- Moisture
- Damaged Brake Line
- Loose Bleeder Valve
- Damaged ABS Module
1) Normal Wear and Tear
Every component of the car has a specified service life. The brake shoes or pads of your vehicle wear down with time, and more fluid is pushed into the brake lines through the wheel cylinders. This results in a higher consumption of brake fluid and the level of the fluid will start dropping very quickly.
2) Leaks
The different parts (like clippers, master cylinders, and brake lines) of your braking system may start leaking over time. These leaks immediately lower the brake fluid level and harm the braking system.
3) Overheating
An overheated braking system results in boiling brake fluid, which results in vaporization and fluid loss. This overheating occurs as a result of the old brake fluid or the heavy braking system.
4) Wrong Fluid Type
Incompatible fluids may react with the internal components of your braking system, which may lead to fluid loss and poor performance of the braking system.
5) Moisture
Brake fluid is hygroscopic and can absorb moisture available in the air. With time it absorbs air and becomes less effective. Hence, the fluid level drops.
6) Damaged Brake Line
The internal component of the braking system may wear out with time and become damaged. As the steel parts can corrode, and it happens more frequently in snowy areas.
7) Loose Bleeder Valve
The bleeder valve is linked to the brake caliper and the drum. A damaged or loose bleed valve may result in a brake fluid leak.
8) Damaged ABS Module
The ABS braking system is a highly pressurized system. Over time, the seals of this system may corrode and wear out. This may result in the leakage of the fluid.
How to Check Brake Fluid
- Firstly, you need to park your car on leveled ground.
- Turn the engine off and let it cool for a few minutes.
- Raise the vehicle’s hood and search for the brake fluid reservoir. The brake fluid reservoir is most commonly installed near the firewall on the driver’s side of the engine bay. It is a metal or plastic tank that usually has a black cap.
- See the marking on the reservoir’s side and look at the fluid level. The reservoir usually has maximum and minimum markings. The fluid level should be between the minimum and maximum markings.
- If the brake fluid in the fluid reservoir is less than the minimum marking, add the fluid until it reaches the maximum mark. Use brake fluid according to the manufacturer’s recommendations.
- If the fluid level in the reservoir is between maximum and minimum markings, check the fluid color. If it is slightly yellowish or clear in color, it means your fluid is in good condition. The cloudy or dark fluid indicates that your fluid is contaminated, and you need to flush it.
- If you find any leaks or spongy brakes, consult the professional immediately.
How to Change Your Brake Fluid
The brake fluid has to be changed every 2 to 3 years. Following are the steps to change the fluid:
- Gather all the materials and tools (like the new brake fluid, the brake bleeding kit, a piece of clean cloth, and a wrench) required to change the brake fluid.
- You need to park your car on the leveled ground and turn the engine off.
- Wait for a few minutes and let the engine cool down properly.
- Remove the negative terminal of your vehicle’s battery before moving forward.
- Find the brake fluid reservoir. Raise the vehicle’s hood and find the reservoir. The brake fluid reservoir is most commonly installed near the firewall on the driver’s side of the engine bay.
- Before opening the reservoir, properly clean the reservoir’s cap to prevent solid contaminants from going into the braking system.
- Remove the reservoir cap and remove as much of the old brake fluid as possible by using a syringe or turkey baster. Don’t discharge any brake fluid on the painted surface of the car, as it may lead to damage.
- Refill the reservoir till the maximum level. Use the fluid recommended by the manufacturer.
- Now, it’s time to find the brake bleeder for each brake caliper. The brake bleeder is usually present on the caliper’s backside.
- Now, loose the bleeder screw and ask your helper to press the brake pedal so that the old fluid completely drains out of the bleeder screw. Continue pressing until you notice the new fluid. Keep an eye on the fluid level and refill it if needed.
- Repeat the above step for every brake caliper. Start doing it with the caliper away from the reservoir and gradually move to the caliper present near the reservoir.
- After finishing the bleeding process for all brake calipers, add new brake fluid into the reservoir up to the max level.
- After adding the new fluid, it’s time to test the braking system to ensure its efficient performance.
How much does it cost to change the brake fluid?
The brake fluid change or flush cost varies according to the vehicle model, labor cost, and the type of fluid’s brand. The average cost to change the brake fluid is from $70 to $140.
FAQ Section
What is the function of the brake fluid?
The brake fluid is used in the brake system to transfer the brake pedal force to the brake shoes or pads.
How often does brake fluid need to be changed?
It is recommended to replace the brake fluid every 2–3 years or 30,000 miles. You should check your car’s manual to find the exact time. Avoid driving with dirty fluid; it may harm the whole braking system.
Can I drive with the low brake fluid light on?
Yes, you can drive, but it is not recommended to drive with low brake fluid light. The low brake fluid levels can cause vibrations as you press the brake pedal. However, low fluid levels can’t damage the braking system, but they may decrease the stopping power. But driving a car with low fluid levels can be dangerous. The ability to stop the car may vanish at any moment, and that can cause serious accidents.
What are the signs of low brake fluid?
- Soft or spongy brake pedals
- Increased stopping distance
- Squeaking noise
- Illuminated brake warning light
- Brake fluid puddles
- Dirty brake fluid
- Vehicle vibration
What happens if I don’t change my brake fluid?
If the brake fluid is not replaced, it absorbs moisture, which accumulates within the braking mechanism. As the water content rises, the brake fluid’s boiling point decreases, leading to excessive heat and subsequent boiling of the fluid. This results in compromised brake efficiency.
How do you know if your brake fluid is bad?
Typically, brake fluid has a light, transparent appearance. If it appears dirty or opaque, it indicates that the brake fluid requires replacement. The reservoir usually features a label indicating the “full line.” If the brake fluid level drops below this line, it signifies that you need to change the brake fluid or replenish it.
What color is brake fluid?
Brake fluid is typically clear to slightly yellowish in color, but it can also be a light brown or amber color depending on the type and brand of brake fluid. It slowly change to a darker, oil color as you drive.