Your vehicle’s brakes are one of its most overlooked components when it comes to maintenance. Reliable, high-performing brakes, however, are vital to your safety. Follow the guidelines in your vehicle owner’s manual for how often to change brake fluid. If none are given, it’s good practice to bleed brakes every other year or whenever you change the brake pads. In this video, we show you how to bleed brakes.
Video transcript: Three Brake Bleed Methods You Need to Know
Featuring John Gardner, host of Motorhead Garage, and Leonard “Len” Groom, AMSOIL Director of Product Marketing (author profile).
John Gardner: If you have to replace a caliper, a brake hose, a brake line or a master cylinder, or you open up that brake system anywhere, you’re going to have to bleed it. Welcome to this AMSOIL Tech Tip. We’re talking about bleeding the brakes, and there are plenty of ways you can do it. You can do it with manual bleeding, which takes two people: pump, pump, pump, press it down and open the bleeders. There’s vacuum bleeding, which uses a shop source of air to create a vacuum and pull fluid from the top down. And there’s pressure bleeding, where you put clean fluid at the top and push it through. Clean fluid, and good fluid like AMSOIL. Make sure you’re using the best.
Better yet, I can show you those methods in action. The first one is gravity bleeding. Gravity bleeding is easy. Make sure your master cylinder is topped off, then just open up the bleeder and let it drip. But you can only do one wheel at a time.
Manual bleeding, as I mentioned, takes two people. Someone’s going to be up in the car: pump, pump, pump. Once he pumps, he holds the brake pedal. While he’s holding the brake pedal, you open up the bleeder, and it forces the air out of the system.
After that, there’s vacuum bleeding. That takes a shop air supply; plug it into the vacuum bleeder. Then you put it on your bleeder, open up your bleeder, and you’re creating a vacuum. You’re pulling the fluid from the master cylinder all the way down to the container.
Last but not least, there’s pressure bleeding. Pressure bleeding uses clean brake fluid. You put it in the container, then you take an adapter and put it on top of the master cylinder. When you do that, you’re forcing clean brake fluid through the system.
Len, air in a brake system is a problem. But people also don’t realize that if you open up any part of the cooling system on a car, you’re going to have to bleed it, because radiators today sit low and the engine sits high. That air in there is going to cause problems. It’s also going to wreak havoc on coolant.
Len Groom: It is, because once again, when you have less coolant or you have a hot spot, it can create problems. It puts more stress on the cooling system in general. But I think what gets people is, what am I supposed to put in there? It’s not just grab a bottle of the green stuff and pour it in your vehicle anymore. As aluminum has become more prevalent, different fluxes are being used to build aluminum radiators, so compatibility plays into it. So what do I use? How do I match the color?
Well, at AMSOIL, we’ve made it nice and easy. We’ve got a heavy-duty coolant, and we’ve got a passenger car coolant. They’re compatible with pretty much anything on the market, and we say that right on the bottle. More importantly, they’re 50/50 premix. Some people say, “Well, I don’t want to buy a half-gallon of water.” What I say at that point is that water is a huge variable depending on where you get it. There could be contaminants in there that create corrosion, and aluminum is way more susceptible to corrosion than the old cast-iron blocks and heads of yesteryear.
John Gardner: Yeah. And if you don’t know what to put in your car, no worries. Just go to amsoil.com. Type in your year, make and model, and it’ll show you what coolant, what oil, what transmission fluid, whatever you need.
Tools you need to bleed brakes
- Bleeder-valve wrench
- About 24″ of clear plastic tubing with an inside diameter of 1/4″ – 3/8″. Ensure it slides snugly over the bleed screw.
- Catch pan
- Hydraulic floor jack
- Jack stands
- Brake fluid
Secure and raise the vehicle
Starting at the furthest wheel from the brake-fluid reservoir, use the hydraulic jack to raise the vehicle off the ground. Slide a jack stand underneath the vehicle’s pinch weld or similar support point. Slowly let the vehicle down onto the jack stand.
Don’t support the vehicle with the hydraulic jack alone since it can collapse – make sure it’s supported with jack stands.
Locate the bleeder valve
The bleeder valve is often covered with a rubber cap. You may need to remove the tire for access.
Remove any dirt or debris and remove the cap. Slide the wrench over the bleeder valve and then push the plastic tubing over the screw to route the fluid into the catch pan. Ensure the tubing is snug on the bleeder screw.
Have a helper pump the brake pedal
While underneath the vehicle holding the bleeder-valve wrench, have someone sit in the vehicle and pump the brakes until the system builds pressure.
With the person in the vehicle holding the pedal down firmly, open the bleeder valve. Brake fluid should travel down the tubing into the catch pan. It’s important to use clear tubing so you can see any air bubbles in the fluid.
Communication is key
Throughout the process, maintain communication with the person depressing the brake pedal.
He or she should indicate when the brake pedal has hit the floor. Then close the bleeder screw and notify the person in the vehicle. He or she can then release the brake pedal. Pump the pedal to build pressure and repeat the process until clear, new fluid with no air bubbles emerges from the bleeder valve.
Air is compressible, which leads to spongy pedal feel, so make sure to remove all the air from the lines.
Check the reservoir level
Throughout the process, pause occasionally to check the brake-fluid reservoir level. Use fresh fluid to ensure it’s full. (Make sure to use the correct brake fluid, usually DOT 3 or DOT 4.) Allowing it to deplete will introduce air into the system, which will require you to bleed it from the lines.
Once you’re finished, tighten the bleeder screw. Make sure you wipe the area down since brake fluid can be corrosive, especially to painted surfaces. In some situations, you’ll want to use brake cleaner or plain water to rinse brake fluid off surfaces. After the area is clean, reinstall the rubber cap.
Move to the next brake
Remove the jack stand from the wheel where you’re working and move to the next-furthest wheel from the reservoir, which is likely the other rear wheel. Again, raise and support the vehicle. Then repeat the above process, being mindful to continually check the brake fluid in the reservoir.
Top-off the reservoir
After bleeding all the brakes, top-off the brake fluid in the reservoir before driving the vehicle.
That’s how to bleed brakes. It can be a challenge, especially if you run into a stubborn bleeder valve that doesn’t want to open. Use penetrating oil to loosen it and be patient. Most do-it-yourselfers with a little experience can bleed brakes without issue.
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Brad Nelson is an AMSOIL Technical Writer II who develops content about lubricant technology, product performance and vehicle maintenance. He works with engineers and product specialists to translate testing, application requirements and approved performance claims into clear customer guidance. Nelson’s work includes AMSOIL Blog articles, AMSOIL Magazine features and technical explanations concerning motor oils, gear lubricants, vehicle systems and maintenance practices.
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