When you are bleeding brakes, you need to let out air from the brake fluid. If there is no brake fluid to rear brakes when bleeding, the entire process fails. Let’s find out why this might be happening and what you can do about it.
The braking system in a vehicle is one of the most essential components. Having a well-performing brake system is necessary for safe driving. It is crucial to maintain the brakes every once in a while to ensure that they don’t malfunction in the middle of a ride.
Maintenance of brakes involves checking the brake pads and rotors, flushing and bleeding the brake fluid level, and checking and replacing any worn-out parts of the brake system.
One of the main issues we face with the braking system is that the brake pads do not transfer the brake force properly to your wheel. In such a scenario, you have to press the brake pedal several times to get your vehicle to come to a complete halt.
Bleeding the brakes is usually the first step of the brake maintenance process when this happens. But sometimes, the brake fluid does not flow to the rear brakes in this process. Read on below to find the possible causes of why there is no brake fluid to the rear brakes when bleeding.
What Is The Purpose Of Brake Bleeding?
The reason for bleeding your brakes is to remove any air bubbles trapped inside the brake lines. When there are air bubbles inside the brake line, the brake fluid will take some time to reach the calipers.
Any problem in the braking system can be dangerous, and it is crucial that you resolve it as soon as possible. If you find no brake fluid coming out at the rear brakes during the bleeding process, then it can be a sign of an issue in the braking system.
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6 Reasons Why Your Brake Fluid Does Not Flow To Rear Brakes When Bleeding
There are several probable reasons why there is no brake fluid on rear brakes when bleeding.
#1. Faulty Brake Screw
One of the main reasons for brake fluid not to bleed during the bleeding process is a faulty brake screw. Because the brake caliper needs the brake fluid to function, there is a bleed screw located in the topmost part of the brake caliper.
It acts like a valve that allows bleeding air inside the brake lines and into the brake fluid.
You will find the bleed screw at the back of the wheel on the brake caliper. The bleed screw is exposed to dust, mud, and dirt coming out of the moving wheels and overheating while applying brakes.
It, therefore, resides in a challenging environment. All these exposures to extreme conditions result in rusting or corroding of bleed screws.
You would have trouble removing a corroded or rusted bleed screw. Even if you are able to remove the bleed screw, there will be no bleeding of the brake fluid because the rusted parts of the screw are blocking the bleeding pipe.
Also read: What kind of brake fluid do Harleys use?
#2. Bleed Procedure Is Wrong
Even though bleeding brake fluid is an easy process, it is possible that you might be doing it wrong, and that is why no brake fluid comes out. There is also possible nothing wrong with the braking system, but the bleeding process you are following is not the right one.
There are five different methods of bleeding the brake fluid. Some of the procedures require just one person, while some require two.
Method 1: Pump And Hold
Get yourself a partner as it is a two-person job. Either your or your partner needs to apply pressure on the brake pedal. It will help pressurize the brake circuit. The other person should do the bleeding. The person who is pressing the brake pedal needs to do it in a specific manner.
Press the pedal in a pulsating motion by frequently pressing the brake pedal five-six times, and then on the last press, hold the brake pedal pressed with their legs.
While the first person keeps the brake pedal pressed, the other person should find the bleed screw on the caliper and slowly unscrew the bleeding screw. Once the screw is loose enough, wait until you see the liquid coming out of the bleeding screw.
When it happens, you can now tighten the bleeding screw back to its original position. You would need to repeat the same process three to four times on every wheel to properly bleed them.
Method 2: Gravity Method
It is probably the most simple technique to bleed the brake fluid, and you can do it on your own. All you need to do is open the bleed nipple in this method. The brake fluid reservoir is above the bleed nipple; thus, gravity will do its work, and brake fluid will bleed on its own.
Method 3: Pressure Method
In this method, you would need a pressure pump. Take a pressure pump, connect it to the brake fluid reservoir or master cylinder, and open up the bleeder valves. It will pressure the system, and brake fluid will drip down the bleeder valve.
Method 4: Vacuum Method
You need to use a vacuum cleaner pump to bleed the brake fluid in this method. All you need to do is connect the vacuum pump to the bleeder valve. Open and close the vacuum pump a few times until the air bubbles inside the brake line are released out of it.
Method 5: Reverse Method
As it is clear from the name, this method requires you to push the brake fluid inside the brake fluid reservoir through the bleeder valve using a pump. With increasing the brake fluid level, the air bubbles inside will release out of the brake line on their own.
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#3. A broken Hose Pipe
The hosepipe carries the brake fluid from the brake fluid reservoir or the master cylinder and delivers it to the brake caliper, which essentially stops the vehicle. When the hose pipe is broken or damaged, it won’t carry the brake fluid to the caliper.
Since there is no brake fluid at the brake caliper, it won’t apply any pressure on the brake pad. When you press the brake pedal, no brake fluid will come out.
In the case of a faulty hose pipe, there can also be brake fluid leakage.
#4. A Faulty Proportional Valve
A proportional valve is responsible for maintaining the brake fluid pressure in the rear brakes. If there is an issue with proportional valves, it will affect the rear brakes.
If, while bleeding, there is no brake fluid to the rear brakes, the most likely cause is that there is an issue with the proportional valve.
Any issue in the proportional valve will not cause any trouble with the front brakes. If the problem exists only with the rear brakes and not the front one, then a faulty proportional valve is the issue.
#5. Issue With Brake Calipers
The wrong fitment of brake calipers can result in no brake fluid to rear brakes when bleeding. Brake calipers are direction sensitive, so you need to put them in a specific direction for proper fitting. There are L and R marks on the brake calipers to demonstrate how to fit them on the wheels.
#6. Rust and Corrosion
Rust and corrosion are the main culprits behind many brake-related issues. Since brakes are exposed to high heat, dust, water, mud, and other extreme conditions they often rust and get corroded.
If rusting happens in the brake pipes and bores, it will diminish the pressure in the brakes, and it can result in no brake fluid to rear brakes when bleeding.
You might like to read: What Size Wrench For Brake Bleeder Valve?
What Can You Do If No Brake Fluid To Rear Brake When Bleeding?
Once you have identified the issue as to why there is no brake fluid to rear brakes when bleeding, it is time to resolve the issues.
Make sure that you are following the right process for the bleeding. Use the suitable brake fluid depending on your car’s make and model. If the brake fluid is not bleeding at just one wheel or a single caliper, then there is a problem with the caliper piston.
Replace the piston if it is not working properly. Check and replace any corroded pipes and brake screws.
If you are not able to solve the issue on your own, you better get your vehicle checked out by a professional mechanic. The Brake system of your car is not something you should take chances with.
No Brake Fluid Coming Out When Bleeding
The performance of a car’s braking system deteriorates over time with use. You will feel that the braking power is not what it used to be. Over time, air bubbles get inside the brake fluid, which is the main reason for the delayed brake response.
While bleeding the brakes, often people find that no brake fluid is coming out. If such a situation occurs, there is a possibility that something is wrong with the braking system.
But before you go looking for faults, make sure that you are following the correct bleeding process. A faulty brake screw and proportional valve can be the reason. Rusted bore and brake pipes can also be the reasons for brake fluid not bleeding correctly. Components like brake calipers, if not correctly installed, can also result in issues during the bleeding process.
Why won’t My Brakes Bleed Properly?
If your brakes are not bleeding correctly, you can do a few things. First, make sure that you follow the proper bleeding method and follow all the steps correctly. Then check the baking system. Look out for any faulty components.
The braking system sustains harsh conditions like mud, dirt, dust, and overheating. Check out for any defective sports or rust and corrosion as the damage can cause brake fluid leakage, which can result in brake fluid not bleeding.
Make sure that all the brake components are installed the right way. Also, if you can not seem to pinpoint the cause for your brakes not bleeding correctly, then get your car checked by a professional mechanic, as a faulty brake system can be dangerous to drive with.
You might like to read: What Size Is A Brake Bleeder Screw?
Frequently Asked Questions
#1. What would cause brakes not to bleed?
A faulty brake screw or proportional valve or else corrosion in the brake unit can cause improper bleeding.
There are several reasons which can result in brakes not bleeding. A faulty brake screw or proportional valve can be the culprit behind the brakes not bleeding.
Rust and corrosion can damage the hose pipe, or brake pipes can also lead to brake fluid not bleeding. Another cause for brakes not bleeding is wrongly fitting the brake calipers.
It is also possible that nothing is wrong with the braking system. It is you who is doing the bleeding procedure the wrong way. We have discussed some of the correct ways to bleed the brakes.
#2. How do you reset a brake proportioning valve?
You need to find the reset button near the brake lines towards the rear wheel.
To reset the brake proportioning valve, you need to locate the valve first. It is near the brake line at the rear wheels. Near the brake proportioning valve, there would be some buttons.
Identify the reset button near the valve and push the button with your fingers. It will reset the brake proportioning valve and start working correctly. The next step is to inspect the brake pressure to ensure it is working correctly.
#3. Do you open the brake fluid reservoir when bleeding brakes?
No, you don’t need to open the brake fluid reservoir when bleeding.
It is unnecessary to open the brake fluid reservoir while bleeding the brakes. However, while bleeding the brakes, you need to make sure that the fluid reservoir does not get empty. Open the brake fluid reservoir only to check the brake fluid level while refilling or changing the brake fluid.
#4. Why won’t the brakes pump up when bleeding?
Because the piston is sticking to your reservoir bore.
If your brakes don’t pump up when bleeding the brake fluid, the piston might be sticking in the brake fluid reservoir’s bore.
This situation arises when you try to bleed the brake fluid manually. When this happens, and you press the brakes, the pedal will go straight to the bottom, and you will not get enough brake pedal pressure.
You might like to read: Should I Open Brake Fluid Reservoir When Changing Brakes?
A Few Final Words
Due to some issues in the braking system, there may be no brake fluid to the rear brakes when bleeding. A faulty brake component like the brake screw or the proportional valve can result in no brake fluid to rear brakes.
Since the braking system is exposed to extreme conditions like overheating, mud, dirt, and dust, it is possible that some of the components, like the brake pipes or hose pipe, will develop rust and corrode over time.
It is vital to get the brakes on your vehicle checked and maintained at regular intervals to avoid any significant issues. Make sure you do so every few months.
Thank you for reading the article, we hope we answered all your queries regarding brake bleeding problems. You can drop us a word in the comments if you have more questions, and we will try to answer them as quickly as possible.