What happens if you don’t change brake fluid
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Why changing brake fluid matters — and what happens if you don’t
Most vehicles use hydraulic brakes, which utilises pressurised brake fluid to transfer and multiply the force you apply to the brake pedal to the brake calipers. Having good quality brake fluid is important because of how efficiently it transmits force from your input; the more you press on the brake pedal, the more brake fluid gets pressurised, which results in greater pressure exerted onto the brake pads.
However, the quality and efficiency of this critical fluid degrades over time. That’s why regularly flushing your brake fluid is so important.
Why does brake fluid need to be flushed and replaced?
Brake fluid is hygroscopic, which means it attracts moisture from the environment. When brake fluid absorbs water, its boiling point becomes lower and it can cause corrosion in the braking system.
Because the braking process generates considerable heat, brake fluid needs a high boiling point to withstand that heat without vaporising. Over time, heat from repeated braking will slowly degrade the quality of your braking fluid, which, combined with the hygroscopic effect mentioned above, means that your braking system’s performance will be put at risk.
We recommend flushing your braking system every 2-3 years and refilling it with fresh, premium vehicle braking fluid.
What happens if brake fluid is never changed?
Let’s answer that question with another question: what happens if your car is travelling down the freeway and the brakes don’t work?
If your brake fluid is never changed, the accumulated moisture significantly lowers the boiling point of your brake fluid and causes your brake lines to corrode and weaken over time; in some cases, they might even fail. During those demanding moments when your brakes are working overtime and are generating a lot of heat, the aged fluid could boil and turn into vapour. This can result in what’s known as brake fade, where your brakes lose their stopping power.
How long can you go without a brake fluid change?
Brake fluid typically lasts 2-3 years in an average passenger vehicle. Ideally, you should replace your fluid every two years to be safe. But if you take your car in for a yearly servicing (which you should be), then your mechanic will let you know how efficiently your braking system is working.
Now that we’ve explained what brake fluid is and does and why it needs to be replaced, let’s talk about how you can tell when it needs to be flushed — and how to do it.
8 old brake fluid symptoms you need to know about.
Paying attention to these signs is crucial for maintaining your vehicle’s braking performance and ensuring your safety on the road.
- Dashboard’s brake warning light | Many vehicles have a brake warning light on the dashboard that illuminates if there’s a problem with the brake system, which can include low brake fluid levels or issues with brake fluid pressure.
- Soft or spongy feeling in the pedal | If the brake pedal feels softer than usual or goes closer to the floor before engaging the brakes, it could indicate air in the brake lines or a problem with the brake fluid.
- Hard brake pedal | Conversely, if the brake pedal is unusually hard to press, it could mean there’s an issue with your brake booster, because of a blockage in the brake system or due to contamination in the brake fluid.
- Unusual noises when you brake | Grinding, squealing, or other strange noises when you brake can indicate a variety of brake issues, including worn pads/shoes or rotors/drums.
- Leaking fluid | Any signs of leaking fluid near the wheels or under the brake pedal area could indicate a leak in the brake system, potentially leading to low brake fluid levels.
- Poor braking performance | If your vehicle takes longer to stop than usual, or the brakes just don’t seem as responsive, it could be due to degraded or contaminated brake fluid.
- Dirty or discoloured brake fluid | Brake fluid should be relatively clear or have a slight yellow tint. If it appears dark or dirty when checked through the brake fluid reservoir, it’s likely contaminated and needs to be changed.
- Vehicle pulls to one side when you brake | While this can be caused by various issues, including tyre pressure or alignment problems, it can also be due to uneven brake fluid distribution.
If you notice any of these signs, we strongly recommend that you take your vehicle in for a brake system service.
How to change brake fluid
Whilst we always recommend leaving the job to the experts, you can change your brake fluid yourself. The process will always be a little different depending on the make and model of the car in question, but our process will teach you the basics. (If you are not familiar with your braking system or you are not confident to tackle this job, then the safest option is to get a qualified technician to do the work).
(This process is made much easier if you remove each wheel as you work along, as it allows you to better see and manoeuvre around each brake. This will involve safely jacking-up and securing your vehicle as well as following proper procedure to remove each tyre).
What you’ll need
- New brake fluid (check your vehicle’s manual for the correct type and amount)
- A wrench suitable for your vehicle’s bleeder valves
- A brake bleeder kit or a clear tube and a collection bottle
- A friend to help (for manual bleeding methods)
- Safety gloves and glasses
- A clean rag
The process for flushing and replacing your brake fluid
- Prepare your vehicle
- Park your vehicle on a flat, stable surface and ensure it’s in “Park” (for automatic transmissions) or in gear (for manual transmissions). Apply the parking brake.
- Open the hood and locate the brake fluid reservoir on the master cylinder. Clean around the cap to prevent dirt from entering the system when you open it.
- Check the existing fluid
- Before you start, check the colour and level of the existing brake fluid. Dark, dirty fluid needs to be changed.
- Wipe around the reservoir and cap with a clean rag to ensure no contaminants enter the system.
- Drain old fluid
- Start with the brake furthest from the master cylinder (usually the rear passenger side, then the rear driver’s side, the front passenger side, and finally the front driver’s side).
- Attach the clear tube of the bleeder kit to the bleeder valve of the brake calliper and place the other end in a collection bottle. The bottle should contain a small amount of brake fluid to prevent air from going back into the system.
- Open the bleeder valve slightly with the wrench.
- Have another person friend press down on the brake pedal slowly and hold it down. As they do this, fluid and air bubbles will come out into the collection bottle. Close the bleeder valve before your friend releases the brake pedal to avoid sucking air back into the system.
- Flush it again
- Refill your brake fluid reservoir with brand new brake fluid.
- Repeat step 3 until you see clear, new fluid coming out without air bubbles. Make sure to keep an eye on the fluid level in the reservoir, adding new fluid as needed to prevent it from running dry.
- Repeat the bleeding process for each wheel, moving closer to the master cylinder each time.
- Final checks
- Once all the brakes have been bled, refill the brake fluid reservoir a final time. Double-check the fluid level in the reservoir and top it off as needed. Make sure the brake fluid level is within the “MIN” and “MAX” marks.
- Test the brake pedal for firmness while the vehicle is still off. It should feel firm, not spongy. If it feels spongy, there may still be air in the system, and the bleeding process should be repeated.
- Dispose of the old brake fluid properly. It is hazardous waste and should not be poured down the drain or thrown in the bin.
- Safety Check
- Before driving, check your work area for any tools or materials left around. Start your vehicle and carefully and test the brakes at a low speed in a safe area. Make sure the brakes respond properly.
Safety Tips
- Always wear safety gloves and glasses to protect yourself from harmful chemicals.
- Work in a well-ventilated area to avoid inhaling fumes.
- Never reuse old brake fluid and always use the type specified by your vehicle’s manufacturer.
Nip into Natrad for a brake check
Every system in your car is critical, but there are some you can drive a short distance without — your braking system isn’t one of them. If you suspect there’s an issue, don’t risk a breakdown.
Look up your nearest Natrad Autocare mechanics, and let us flush and replace your brake system fluid.
