Brake Fluid Leaking From Caliper: Causes and the Best Fixes

Brake fluid leaking from caliper is a condition that can put your safety at stake when not addressed on time. Several factors can cause brake fluid leaks and, if left unchecked, can be potentially fatal to your car’s performance. If you don’t know much about vehicle dynamics, discovering the main culprit may be difficult.

brake fluid leaking from caliper

We’ve highlighted the main causes of leaking brake fluid from the caliper and how you can fix this problem.

Why Is Your Brake Fluid Leaking From Caliper?

Your brake fluid is leaking from the caliper because of insufficient fluid level, worn brake pads, or a failing cylinder reservoir. Aside from these, there are other culprits responsible for fluid leaking from your brake caliper such as improper installation and defective brake lines.

Your brake leaking fluid is a serious problem that should be addressed immediately. Since this affects your brakes, you don’t want to take a chance. A brake leaking fluid can be potentially dangerous, especially when you start to lose control of your brakes.

In addition, a brake fluid leak repair costs a lot, as replacing a leaking system can cost more than an entire brake system. Hence, you should immediately contact a mechanic once you notice the slightest problem with your brakes.

– Brake Fluid Is Low

Low brake fluid may not seem like much, but it greatly affects your brake’s performance. When this fluid is insufficient, using your brake will cause a buildup of pressure in the seals. As you continue to drive with this low fluid, the pressure buildup gets higher, and your seals can break at this point. When this happens, the fluid in your brakes will leak from the caliper.

– Corrosion on Pistons and Cylinders

Another common cause of leaks from your brake calipers is that your pistons and cylinders are corroded. The piston and cylinder play an important role in transforming heat energy into mechanical energy needed for the engine to work. Pistons move based on forces produced by the liquid or gas pressure inside the cylinder. Hence, the piston and cylinder are closely related since the piston is enclosed in the cylinder.

These can get corroded when the mixture of sulphuric acid, water, and lubricating oil has been allowed to build up. It can also result from exposure to either extreme cold or heat or moisture. Over time, your piston and cylinders will start to rust and have holes in them, leading to fluid seeping from your caliper.

– Damage Caused by Improper Installation

You’ll notice fluid seeping from your caliper if the calipers are installed wrongly. Although installing calipers looks like a breezy task, a lot can be overlooked, leading to improper installation. For instance, during installation, the brake calipers may be overly tightened. When this happens, it will cause the seals to break due to excess pressure.

When the seals break, you’ll notice telltale signs like a puddle of brake or transmission fluid under your car. Seeing this is an indication that your caliper is starting to leak fluid.


– Corrosion Buildup Around Seals

Like every mechanical device, you’ll need to lubricate your brakes as often as possible. When your brakes aren’t properly lubricated or lack any form of lubrication, it’ll cause corrosion around your seals.

When this is the case, your seals will become too stiff and most likely break when there’s excess pressure. Broken seals will damage your calipers and cause them to start leaking fluids.

– Worn-Out Pads

Worn-out brake pads are also a possible reason your caliper leaks fluid. Also known as a brake pedal, this is an important part of a vehicle that sends information to your rotors, causing friction that will slow down or stop your car. Your brake pedal can become worn out due to everyday use, the type of roads you drive on, as well as lack of maintenance. Your driving habits can also affect the longevity of your pads.

When the pads do not work as they should, high pressure and heat will be transferred to your caliper seals. If the seals are not strong enough to bear the pressure, they will break and cause fluid to leak from your caliper. A soft or mushy brake pedal is a sign they’re worn out and is also one of the several brake fluid leak symptoms to look out for.

– Worn Out Rotor, Brake Shoes, and Drums

The rotor, brake shoes, and drums are important components that aid a smooth-running brake system. Like vehicle parts, these are subject to wear due to long-term use or lack of maintenance. When these are bad, the piston will move beyond how it is supposed to, leading to increased pressure.

Again, the seals won’t be able to handle this pressure over time, and they could get broken. This will, in turn, affect the caliper, which will start to leak brake fluid. One obvious sign that these components are broken is that braking becomes rougher and more difficult than before.

– Defective Brake Lines and Hoses

Although not a common cause, defective brake lines and brake hoses can cause fluid to leak from your caliper. These lines and hoses are often made with durable materials capable of withstanding pressure and harsh conditions. However, long-term use will cause them to become susceptible to rust, breakage, and corrosion.

Your brake hose could tear, and your lines or fittings could break or become damaged due to a forceful collision. Whatever the case is, defective brake lines and hoses will surely cause your caliper to leak fluid.

– Failing Bleeder Valve

Every braking system works with a bleeder valve. Also known as a bleeder screw, this valve isolates or stops fluid and air flow into the brake system. Over time, the bleeder valve can start to fail due to damage from rust, and it can even get pushed out from its place due to forceful impact.

Failing Car Bleeder Valve

Since the bleeder valve is found in the caliper, it can cause fluid leakage from the caliper when it is not working as it should.

– Faulty Brake Master Cylinder Reservoir

Also commonly referred to as the master brake cylinder, this component feeds brake fluid to your brake circuit. It then converts the circuit’s pressure on the pedals into useful hydraulic pressure. Your master brake cylinder comes with a reservoir that stores brake fluid and protects it from contaminants.

The master cylinder reservoir is made with polymer plastic that can give way to wear, especially from excess heat. It could also be that the rolling pin that connects the reservoir to the master brake cylinder is damaged, so the reservoir isn’t properly placed. When the master cylinder starts to crack, it’ll cause fluid to leak from your caliper.

– Bad ABS Module

The anti-lock braking system (ABS) module is an essential part of a vehicle; it prevents your wheels from skidding or locking up when you suddenly apply brakes on emergency shutdown.

Your ABS module is held together by several brake seals. These can give way to rust or wear if they’re not well lubricated or maintained. In turn, these could seriously damage your caliper, causing them to leak fluid.

How Do You Fix Brake Fluid Leaking From Your Caliper?

To fix brake fluid leaking from your caliper, you can start by repairing broken seals and pistons. You should also fix or replace your ABS module and ensure your fluid level is the right amount. Aside from these, you can also try replacing worn out pads.

Fixing Brake Fluid Leaking From Caliper


The tools you need to repair caliper leaks include high-quality brake fluid, a seal kit specific to your vehicle, and a bleeder wrench. You can get the seal kit from any store that sells auto parts. You may also need a flat-headed screwdriver when repairing a caliper leak.

 Here are some more solutions to fix a leaking caliper.

– Refill Brake Fluid

If you have low fluid in your brake system, you’ll need to refill it to the right amount. But you’ll first need to carry out a thorough diagnosis to be sure that insufficient fluid is what is causing your calipers to leak. Once it is discovered to be the culprit, you should immediately top up this fluid.

Your caliper should stop leaking fluid when this is done. Also, make sure you carry out routine checks on your fluid level to ensure it doesn’t get too low again.

– Lubricate Piston and Cylinder

Corrosion on your piston and cylinder can also cause a leaking caliper, so the solution is regular lubrication of these parts. If they have not been severed or damaged due to dryness, lubricate your piston and cylinder every three to six months. It would help if you also replaced the fluid in your brake system as often as possible to avoid corrosion due to contaminants and dirt.

Another recommended option would be to manually clean your pistons and cylinders with a cleaner. If they’ve been too damaged to work properly, then you’ll need to visit a mechanic and replace these parts.

– Get a Professional Mechanic for Installations

If your caliper was not properly installed, you should contact a professional mechanic to redo the installation. Before contacting a mechanic, you may want to try and loosen the caliper slightly if it appears too tight.

If this doesn’t work, having a licensed mechanic check it out is the safest and best solution. If you’re sure you are experienced at installing calipers and want to do it yourself, then pay attention to the process to avoid mistakes that can result in wrongly installed calipers.

– Replace Corroded Seals

If your seals are corroded, you should first try to lubricate them. If they work after lubrication, you may not need to replace them. However, if they still don’t work, a replacement is the next option. Replacing corroded seals should be left to a mechanic, although it is pretty easy to do it yourself.

To replace corroded seals on your own, you’ll need to purchase a seal kit specific to your vehicle from an auto repair shop. Once your kit is ready, locate the caliper and remove it from your car by unscrewing its bolts from the suspension. After doing that, take out the corroded seals from the brake piston. Clean the surface of the piston and its surrounding area with a brake cleaner, then install the new seals.

Once that is done, reinstall the caliper and bolt it back in place correctly. Make sure you turn on your bleeder valve at this point so that excess air is let out of the brake system.

– Repair Worn Out Pads

If your brake pads no longer work as they should, you’ll need to repair them. Repairing a faulty pad can be as expensive as getting a replacement. Hence, we always recommend replacing worn-out pads with new ones.

Depending on the quality of the pads and the labor cost, your replacement may or may not be too costly. If you can, you should invest in high-quality replacement services regardless of its price to cut future expenses.

– Fix Worn-Out Rotors, Brake Shoes, and Drums

Since the rotors, brake shoes, and drums are an essential part of your brake system, you should fix or replace them immediately after they malfunction. You can contact a licensed mechanic who will diagnose the problems and highlight the parts that need replacement.

Make sure repairs or replacements are carried out before you drive again. When these brake components are all working perfectly, your caliper should stop leaking fluid in no time.

– Replace Damaged Brake Lines and Brake Hoses

Reinstalling new brake hoses and lines is another great way to eliminate the problem of calipers leaking fluid. If you’re certain that your brake hoses and lines are the cause of the problem, you should seek the service of a professional mechanic. However, you can also carry out this task once you have the required skills and equipment. To replace a broken hose or line, you first need to raise your vehicle and support it with a jack stand.

It would be best to be very careful at this point, as you will have to remove the tires and take out the mounting clips that are holding the lines in place on the caliper. After doing this, you have to locate the defective line. Detach it from its fittings in the caliper and install the new one.

Reconnect the mounting clips and inspect what you’ve done to be sure you didn’t miss reconnecting any part. Afterward, use your bleeder valve to eliminate excess air that may have gotten into the brake system.

– Repair Faulty Bleeder Valve

Your bleeder valve is a crucial component of your brake system and will need instant attention once it is faulty. If you’re certain that your bleeder valve is causing your caliper to leak, you should immediately contact a mechanic for repair. However, you can choose to fix the valve yourself: first, rid the bleeder valve and its surrounding area of dirt by cleaning it with a cleaner. After that, locate the bleeder screw and gently remove it from the wheel cylinder.

Take a brush cap applicator and apply the needed amount of thread sealant to the bleeder screw. Let the screw dry for about 20 to 30 minutes before you attach it to the wheel cylinder. Once you’ve successfully fixed your bleeder valve, you should eliminate excess air from the system.

Your caliper may still leak fluid even after it has been replaced because it was installed wrongly. A new caliper can also leak fluid when excess air is bled out of the brake system, or the bleeder valve is faulty. Inspect your caliper to be sure it is properly installed, and do what is necessary if you detect any inconsistency. Also, make sure your bleeder valve is working correctly as well.

– Fix the Master Brake Cylinder Reservoir

Fixing your master cylinder reservoir will also help with the problem of a leaking caliper. Once your cylinder reservoir becomes faulty, the best option is to replace it with a new one. Although a professional mechanic will do a more efficient job, you can also replace it yourself. First, you’ll need to pop the hood of your car and firmly secure it.

Locate the master brake cylinder, which is usually close to the pedal area. Secure it from moving by using a vise or clip, and then remove the roll pins that attach the reservoir to the cylinder. Try to pry the reservoir away from the cylinder using a flat-headed screwdriver to loosen it. Also, remove the old rubber grommets holding the reservoir to the seals.

Take out the reservoir and unscrew its cap to drain out the remaining fluid. Your new reservoir would come with new rubber grommets that must first be lubricated before they are attached to the master brake cylinder. 

After attaching the new grommets to the cylinder, install the new master brake cylinder reservoir and reconnect the rolling pins that hold the reservoir to the cylinder. Fill the new master cylinder reservoir with the needed fluid and bleed out the unwanted air.

– Repair Faulty ABS Module

Fixing a faulty ABS can be pretty expensive and also very technical. Carrying out repairs on a faulty ABS module can be less pricey if the ABS controller isn’t too damaged. On the other hand, severe damage will increase the cost of repair or replacement. You should ensure that a certified mechanic carries out the repair task to avoid improper installation or repairs.

– Go For Routine Brake Service and Maintenance

You can prevent your caliper from leaking by performing routine brake service and maintenance. Make sure the fluid level in your brake system is sufficient. Also, inspect your brake hoses, lines, seals, rotors, and other important components to ensure they are not corroded or rusted. Perform routine checks on your calipers to make sure they appear fine and are working perfectly.

Frequently Asked Questions

1. Is It Safe To Drive With a Leaking Brake Caliper?

No, it is not safe to drive with a leaking brake caliper. Driving with a leaking caliper can make it difficult to control your brakes, which can be fatal. Rather than take a chance with a leaking caliper, you should immediately contact a repair company to help resolve this problem.

2. What Are the Signs of a Brake Fluid Leak?

The signs of a brake fluid leak include your car’s warning light coming on and when your brake pedals reach the ground when you step on them. Your pads also become too soft or mushy and no longer feel resistant when driving.

Another telltale sign that your fluid is leaking from the brakes is that you’ll notice a trail or puddle of fluid under your car. All of these will make it very difficult to control your brakes. Driving with an erratic braking system can lead to a fatal accident, so identifying the signs of a leaking caliper on time will save you from trouble.

Brake Fluid Is Leaking From Caliper Conclusion


If you notice that fluid is leaking from your brake caliper, it means your car requires urgent attention, or your brakes could be affected. Here’s a summary of all the key points discussed in this article:

  • If you’re wondering why is brake fluid leaking from caliper, it is a sign you have damaged or corroded seals.
  • Worn-out pistons and cylinders can also cause this. Another reason why your caliper is leaking fluid is that your bleeder valve is faulty.
  • To fix this, you’ll need to replace your broken seals, pistons, and cylinder. You’ll also need to repair your bleeder valve, master brake cylinder reservoir, and ABS module. Ensure your fluid level is correct and replace damaged brake hoses and lines immediately.
  • Driving with a leaking caliper is possible but not advisable because you could lose control of your brakes, which can be fatal.

Now that you can identify why your caliper is leaking fluid, it’ll be very easy to troubleshoot the problem and save time.

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