A car that can’t stop is a death trap. That’s why your brakes are so crucial. Keeping them in good shape should be your primary goal. With most cars and trucks running on hydraulic brake fluid systems, keeping your brake fluid level steady should be a priority.
Your brake fluid reservoir has a MAX and MIN level. Ideally, your brake fluid level should be as close to the MAX level as possible but never below MIN.
A fluctuation between or below these levels could be due to a wide range of causes. Some of the most common causes include:
Worn Brake Pads
As brake pads wear out, they get thinner and thinner. This forces your caliper pistons to extend further to maintain contact.
The extension creates some extra space in the system your brake fluid has to fill up. This will translate into a brake fluid drop that you can observe on the reservoir.
Normally, the drop will be minimal and rarely goes below the MIN line. Moreover, you shouldn’t witness it if you recently changed your brake pads – unless a problem is making them wear out really fast.
This is how you can lose brake fluid without a leak.
Leaky Brake Lines and Hoses
Even though brake lines are the hardiest and most reliable plumbing pieces in a car, they can still corrode and crack over time.
If this happens, they will leak fluid on their own or every time you step on the brake pedal.
Brakeline damage could happen naturally as the car ages or as an accident if something snags a line or two.
Another common point your lines could leak is at joints. If the bleed nut, for instance, isn’t well secured, you will lose some brake fluid.
Finally, the rubber brake hoses that connect the brake lines to your calipers could be brittle and damaged. They could also snag on something when driving over debris.
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A Damaged Master Cylinder
Your master and slave cylinders transmit pneumatic pressure from your brake pedal and the brake booster system.
They make it easier to apply the massive pressure needed to bring a car to a halt. If there are any leaks around their pistons, your brake fluid could leak out, causing a drop in brake fluid levels.
A Faulty ABS Module
If your car has ABS, it stores some high-pressure brake fluid in the ABS pump. Over time, the seals in the ABS reservoir could wear down, causing leaks.
Damaged Calipers or Pistons
The last weak spot in the system could be your calipers and their pistons. Regular tear and wear could make them leak oil over their seals.
Moreover, the severe impact that damaged the wheels could also get to them. It’s not easy to damage calipers or drums, but they could get leaky – especially if they are very old.
Signs That You Are Leaking Brake fluid
Luckily, keen drivers can identify a brake fluid leak before it is too late. If you notice it and the levels are dipping very fast, it is wise to stop driving and have your car towed to a repair shop.
Some of the signs to look out for include:
Low Brake Fluid Levels in the Reservoir
The first sign that you are losing brake fluid is a drop in the reservoir bottle. If you are keen, you will note any fluctuations every time you pop your hood to inspect your fluids and the engine bay.
A gradual loss over time that doesn’t dip below the MIN line is normal. It indicates that your brake pads are aging.
However, a drastic drop over a short time or anything that lowers the oil level way below your MIN mark is a bad sign.
A Brake Warning Light on the Dashboard
Some modern cars also have sensors to monitor brake fluid levels. While some will specifically tell you what problem you’re dealing with, others will pop on the Brake warning light.
The brake warning light could mean a couple of things.
- The parking brake is engaged
- You have issues with your ABS module
- You have a faulty sensor in the brake master cylinder or the parking brake
- Low brake fluid levels in your master cylinder
Your brake light should be combined with other signs to conclude that you are losing brake fluid.
A Fluid Puddle Under Your Car
This is another hard-to-miss sign that you are leaking brake fluid. The catch is your car has a lot of fluids. Ensure that you are not confusing the fluid puddle you see.
- Coolant: Bright colors similar to what’s in your coolant reservoir tank. Check this post for more on coolant leaks
- Transmission fluid: Pink to red look. Check this post for more on transmission fluid leaks
- Engine oil: Black to a golden brown. Check this post for more on engine oil leaks
- Brake Fluid: Clear, yellow, or dark brown
The location of the leak determines what part of the brake system is leaking. It could be under your master cylinder, somewhere under the brake lines, or under any of your four wheels.
Rubbery Feeling Brake Pedal
When the fluid levels in your brake system drop, the brakes lose their usual punch. The pedal has to travel longer to compensate before the brakes bite.
This translates to a spongy feel on your foot as you brake.
Normally, the brake pedal should start soft and get stiffer the deeper you press it. Any inconsistency in this travel hints at low fluid levels or air in the system.
Check this too: What Happens When Your Brake Booster Goes Bad?
Your Brake Pedal Drops Straight to the Floor
This is the last and most dangerous sign that you have low or perhaps no brake fluid in your system.
If your brake pedal drops straight to the ground with little to no resistance, you have no fluid.
It is even more dangerous if the car doesn’t slow down or stop after this.
Stay calm and downshift gears if you can to slow down the car. If your car doesn’t have a manual shift mode, get off the accelerator and let your car coast. Steer it away from danger until it slows down enough to gently apply the parking brake and bring yourself to a stop.
How Much Does it Cost to Repair a Brake Fluid Leak?
The bill will depend on what is leaking. For instance, replacing a single-end hose on one of the calipers would be cheaper than replacing a master cylinder.
Here is a quick breakdown to give you an idea of how much you could spend on different problems.
- Brake line leak: $150-$300
- Master cylinder leak: $400-$800
- Brake caliper leak: $500-$800
- Rear drum cylinder leak: $100-$250
How Do You Fix a Brake Fluid Leak?
Fixing a leak is all about sealing the puncture or replacing the worn-out part. To get to this stage, you first have to identify what the faulty part is.
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If you are good at diagnostics and comb every part of your braking system, you will know what to fix.
If there is some fluid in the system, pumping the brake a couple of times introduces some pressure in the system. This will force the fluid to leak faster, helping you localize the leak.