Need car parts? Select your vehicle
Reading Time: 6 minutes
Summary
  • Some common mistakes DIYers make when bleeding the brakes include using the incorrect brake fluid type, spilling brake fluid on brake pads, overfilling the master cylinder reservoir, and more.
  • Incorrectly bleeding the brakes may result in issues, such as longer stopping distances, spongy brakes, and difficulty braking.
  • It costs at least $80 to have a professional bleed the brakes.

Like most DIY car procedures, bleeding the brakes has its merits. For one, you get a sense of fulfillment and achievement.

However, something that seems straightforward can quickly turn into a nightmare if you don’t execute the steps properly. At worst, you may damage the brake system and jeopardize your safety.

What is Brake Bleeding?

Bleeding the brakes is a process done to remove excess air trapped in the hydraulic system. It’s an important part of vehicle maintenance, as trapped air may cause your brake to feel soft and make it harder to stop your car.

Bleeding makes your car’s braking system more efficient. While there are different ways to do it, you can check out our guide on how brake bleeding generally works.

Common Mistakes When Bleeding the Brakes

Bleeding the brakes is a tedious and difficult procedure. As such, it’s common for DIYers to make mistakes. Here are some of the usual errors to avoid when bleeding the brakes:

Using the Wrong Type of Brake Fluid

Bleeding the brakes also gives you the chance to replace older brake fluid. However, using the incorrect type may affect the seals, damage the system, or even cause brake failure.

It’s a good idea to read the owner’s manual or consult a mechanic to make sure that you’re purchasing the correct type of brake fluid for your vehicle.

Spilling Brake Fluid on Brake Pads

Brake fluid is corrosive and can even damage your car’s paint job. Spilling it on the brake pads may render them useless due to contamination. This doesn’t typically happen while bleeding brakes, but be careful about it anyway.

See also  How Much Brake Fluid Do I Need? Plus Other FAQs

You can prevent this issue by using a hose on the bleeder for better control over the fluid flow. Avoiding overfilling the reservoir can also help keep your brake pads clean.

Overfilling the Master Cylinder Reservoir

As you drive and apply your brakes, the brake fluid heats up and expands. The fluid then expands back into the master cylinder reservoir. This is the reason why your brake fluid level in the reservoir appears higher immediately after a drive. As the hot fluid cools down, you will notice that it will drop back to the normal level.

Overfilling the reservoir above the max line leaves your brake fluid less room to expand. Fortunately, the worst thing this might cause is some fluid leakage around the filler cap.

Stripping the Bleeder

Stripped hardware can make it harder to bleed the brakes. As such, it’s crucial to choose the right equipment to make the process easier.

six point socket or a dedicated brake bleeder wrench
Using a six-point socket or a dedicated brake bleeder wrench will help prevent you from stripping the bleeder screw. | Image Source: Richard McCuistian

There are also brake bleeder kits you can purchase to ensure you have all the necessary tools at your disposal.

Letting Moisture and Debris In

Removing the master cylinder cap and forgetting to reinstall it may allow atmospheric moisture to become part of the fluid, because brake fluid absorbs water. This may lead to contaminated brake fluid, which lowers the boiling point of the fluid and and also causes electrolysis to attack the metal parts of the brake system that carry or interact with fluid.

A compromised braking system will need to be flushed to eliminate moisture and contaminants.

One way to prevent contamination is by cleaning the area around the master cylinder before removing the cap.

It’s also a good idea to purchase brake fluid in small containers to prevent possible air or moisture contamination. Remember to remove any dirt or moisture from the container before opening it.

Do not reuse old brake fluid containers or transfer leftover brake fluid into other containers used for other liquids and chemicals.

See also  How To Dispose of Brake Fluid: Proper Methods and Other FAQ

Wrong Bleeding Sequence

Bleeding the brakes involves a series of steps you need to follow to remove the trapped air in the lines effectively. Not following the manufacturer’s recommended sequence may leave trapped air inside.

The most generally accepted sequence is to start with the wheel furthest from the master cylinder and end with the wheel nearest the cylinder.

Most rear-wheel-drive vehicles are equipped with a front/rear split system. The general rule is to start with the wheel farthest from the master cylinder and work your way toward the closest (right rear, left rear, right front, and left front).

, Avoid These Common Mistakes When Bleeding Your Brakes

Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.

Pro Tip: However, you can’t count on the general rule being applicable on every vehicle. Find out the right bleed sequence to be sure. If you use the wrong sequence, you may never get all the air out of the brake system.

difference between nissan frontier and generic sequence illustration
Notice the difference between the two sequences illustrated. | Image Source: Richard McCuistian

Also check to see if you need to use a scan tool to facilitate bleeding. Sometimes it’s required for a full bleed.

In some cases, vehicles equipped with ABS or a diagonal split section may require a different sequence (right front, left front, right rear, and left rear).

Overtightening the Bleeder Screw

One of the last steps in bleeding the brakes is closing and tightening the bleeder screw. Some tend to overtighten the screw, causing it to break off in the caliper, though this doesn’t usually happen.

Your vehicle’s service manual should have the appropriate torque level to avoid overtightening. Neglecting the correct level may require you to replace the entire brake caliper or drill out the bleeder screw.

Failing to Reinstall the Rubber Cap on the Bleeder

rubber cap keeps the bleeder screw from getting clogged
The rubber cap keeps the bleeder screw from getting clogged. Always put it back if the bleeder has one. | Image Source: Richard McCuistian

Not Bleeding Long Enough

Not bleeding long enough may also leave air pockets in the lines. This defeats the purpose of the process and may affect the braking response. At worst, it could also render the braking system useless. Long air pockets will be moving through the lines so be aware of this.

See also  Why Are My New Brakes Squeaking?

Bleeding the Brakes by Yourself

Bleeding the brakes is generally a two-man job, but you can do it by yourself if you do it right. Mechanics work in pairs to remove the excess air in your braking system to ensure it works smoothly. Usually, one man is responsible for pushing on the brake pedal while the other works on bleeding the brakes and releasing the air.

If you feel like you have the skills to do the job alone, you can use simple homemade tools if no scan tool is required.

illustration of bleeding the brakes by yourself
If you build 4 bottles like the one shown in the drawing and start with a bit of fluid in the bottom so that the hose is below the level of the fluid, you can bleed the brakes by yourself. You might want to use some wire to suspend the bottle while you’re bleeding the brakes. Each bottle will get heavier as fluid accumulates. | Image Source: Richard McCuistian

Allowing the Master Cylinder to Go Dry While Bleeding

If you don’t keep the master cylinder full, you’ll fill the system with even more air than you had to begin with. This requires frequent checking and rechecking of the master cylinder fluid level to make sure you’re not running out of fluid in one of the chambers.

illustration of allowing the master cylinder to go dry while bleeding
Here’s a neat trick you might try with a good clean bottle (see illustration). This method increases the amount of fluid available to the master cylinder, automatically adding more fluid as needed, and the bottle acts as a sight glass so you’ll know when the fluid level is getting too low. | Image Source: Richard McCuistian

If you don’t keep the master cylinder full, you’ll fill the system with even more air than you had to begin with.

– Richard McCuistian, ASE Certified Master Automobile Technician

What Happens If I Bleed the Brakes Incorrectly?

Improper bleeding means you don’t get most of the air out of the line. This results in issues, such as longer stopping distances, spongy brakes, and difficulty braking.

You may also damage the master cylinder, leading to inconsistent braking. Needless to say, these issues may compromise the safety of your vehicle, as you’ll have a difficult time controlling it.

How Much Does It Cost to Bleed the Brakes?

It usually costs somewhere between $80 and $110 to bleed the brakes. The price depends on your vehicle’s year, make, and model. There are also DIY brake bleeder kits you can use if you plan on doing it yourself. They usually go for as low as $8, while some go for as high as $220.

About The Authors
Written By Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at CarParts.com

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

File Under : Braking System , DIY Tagged With : ,
Garage Essentials
Subscribe
Notify of
guest
0 Comments
Inline Feedbacks
View all comments

View all Questions & Answers

expand_more
CarParts.com Answers BE PART OF OUR COMMUNITY: Share your knowledge & help fellow drivers Join Now