Chase: John, you know the number one cause of a spongy pedal is air in the system?
John: Yeah, and if you ever open up a brake system, you're going to have to bleed it. Whether it's a caliper, a wheel cylinder, a master cylinder, brake line, or brake hoses. Once you open it, you're introducing air in the system. And don't forget about that brake fade. If you boil the fluid, air in the system, you're going to have to bleed it. And also, you want to use good fluid to do it with.
Chase: Yeah, and you must follow the manufacture's specifications and sequences. It's very, very important.
John: And we're going to show you have to bleed it with several different methods. Methods like manual bleeding. There's also gravity bleeding, you have a vacuum bleeding method, and there's a pressure bleeding method.
Chase: Well, we better get to it.
John: Now, manual bleeding's a highly effective method to get the air out of the system. But no matter what method you chose, always top the master cylinder off with clean brake fluid because if it runs dry, you have to start the procedure all over again. And always check the manufacture's specification for the bleeding sequence. No, our pickup trucks bleeding sequence is right rear, left rear and we made it to the right front.
Now, with manual bleeding, you're going to need two people. So I have Chase inside of the vehicle and we're going to have to have a line of communication. We're going to have to talk and we're going to have to be able to hear each other. So we have the window down. And how it works is I actually have a catch bottle here because the fluid's going to come out and I want to catch it and I don't want it to go over the floor or any paint on the vehicle. If it does get on the paint of the vehicle, remember, it's hygroscopic. It absorbs water and water also neutralizes it.
So just spray it down with a little water or a water bottle. Don't wipe it. It'll take the paint off. Now, with my bottle, all I'm going to do is I'm going to come over and I'm going to take my wrench and put it over the bleeder. The bleeder nipple's located right here on the caliper assembly and then I'm going to put the bottle, which is submerged in brake fluid, on here. Now why is it submerged in brake fluid? I'll walk you along the process.
Now, as I got it all hooked up, I'm going to ask Chase to pump the pedal. So chase, if you would pump the pedal and as he's pumping the pedal, what's happening with that actual fluid is he's forcing the air all the way down the system and up here to the highest point which is the bleeder. Then what I'm going to do is I'm going to tell him to hold it. But when I tell him to hold it, I need a response that he's holding it to make sure that he's not going to introduce air back into the system by releasing the pedal.
John: All right. So once he's holding it, I know there's pressure on the system. I can go ahead and crack that. Now once I crack that, what's going to happen, you can see the fluid. Matter of fact, you can see the old fluid kind of come out of there and start to fill the bottle. I'm going to close it. Air and fluid at the same time is coming out. And then what I'm going to do is we're going to repeat the process. So I'm going to ask him once again, pump it.
Now if I didn't have it closed, I'm going to suck some of this fluid up in there and I'm going to start introducing air into the system. That's why it's so important to have a good line of communication with somebody inside of the vehicle. Got it?
John: Holding. Once again, he's got pressure on the pedal, the system's filled up with fluid all the way through. The air's going to be at this point. Crack the bleeder. Once I crack the bleeder, you can see the old, nasty fluid start to come out. I close it. Now, don't forget, periodically you're going to have to go up to the master cylinder and refill it. You don't want the master cylinder to run dry or you're going to start the process all over again.
Now, manual bleeding is very effective and I even like to do manual bleeding sometimes after some other bleeding procedures because I'm really forcing the air out of the system. But we'll look at a couple other methods starting with gravity bleeding. Gravity bleeding's an easy way to remove the air from the system and it only takes one person to do it. Now, to gravity bleed, you're simply going to use gravity. I'm going to go ahead and open up the bleeder. And when I open up the bleeder, the air will bubble out first.
Now, once the air bubbles out, the fluid starts coming out because the weight of gravity's pushing down. It's going to flow through and come out. But one precaution, if any lines go up above the master cylinder, gravity won't work because you'll get an air bubble up there and the fluid will stop. So you want to make sure the lines are below the master cylinder and then you can go ahead and bleed it. Two other things. Make sure you use the manufacturer's specification.
Once again, you have to follow the proper sequence. And as you're gravity bleeding, you're dripping into a pan. If you get any on the caliper assembly or any of the paint, just use water. Go ahead and hose it off. Gravity's a great way to bleed. Just make sure you're doing it in the proper procedure. Now, vacuum bleeding has become one of the most popular methods to bleed the brake system. It only takes one person. It's pretty nonexpensive and it's non-intrusive which means you're not messing with any of the anti-lock brake systems and you're pulling the fluid down from the master cylinder into this actual unit here.
Now, the vacuum bleeder, very simple to use. You just get some shop air, you come over and you connect the shop air to the source right here and when you do that, you're creating a vacuum down here, a Venturi. It's actually going to... When I turn it on, it's going to create a suction right here. And then what I want to do is I want to come over and I want to put that on the bleeder. So what I'm going to do is I'm going to come over, put my wrench on first, and then I'm going to put it on the bleeder.
And when I put it on the bleeder, I can go ahead and open up the bleeder. And when I open up the bleeder, I'm going to apply a vacuum which is going to cause a suction here and actually pull the fluid all the way down. So open the bleeder and turn it on. This is also a great way to actually flush the brake fluid from the top all the way to the bottom. Once I see the air bubbles stop, I can go ahead and cut it off. But don't forget two things. Number one, follow your manufacture's specifications for the bleeding procedure and the bleeding sequence.
Go around to each one of the wheels in the order that you're supposed to. And like always, with vacuum bleeding, you're going to pull the fluid out at a pretty rapid rate. So what you want to do is you want to go ahead and make sure that it's topped off with clean brake fluid.
Chase: Another effective way to bleed the brake system is pressure bleeding and it's very simple to do. But always fill up your master cylinder reservoir with clean, fresh brake fluid. And to do this, it's very simple. We're going to remove the cap, install our cap from the kit. Now, [inaudible] our pressure bleeder is full of brake fluid. So all we have to do is pump it up. We're getting some pressure on it. And then we have a valve here. We want to open up our valve.
And now that's going to allow the fluid to go into the master cylinder reservoir. And as we keep pushing pressure against it, it's going to pressurize the system all the way down to the calipers. And then all you have to do is go around and bleed the calipers.
John: It is a very effective method. The only downfall, it could be a little bit costly. Now, take a look at this graphic. If you're old school like I am, you may have had a pressure bleeder tank and it was separated with actual air on the bottom from shop air and clean brake fluid on the top. And what that did, it actually forced it through. Same concept, just a different look. Now, pressure bleeding a system's a great way to bleed the brake system.
Chase: John, you know, sometimes when you're dealing with these ABS systems on these cars, bleeding can be very tough and you're going to have to use a scan tool at some point because you're going to have to be able to open and close those valves inside of there and get that air out of the system.
John: Yeah. There's a lot of nooks and crannies inside of here. We actually have one cut away so you can see inside of it. What Chase is talking about is running these valves up and down. The actual ABS actuator runs them up and runs them down. Sometimes you may run into a position where they're in the down position and you may not get any fluid out at all. So please, follow the manufactures' specifications and the proper bleeding sequence when you're doing any bleeding of brake systems, ABS especially.
Just be patient. Whether you bleed manual or gravity, pressure bleeding, however you do it. You may have to bleed it. Take it out on a small test drive. You may have an air bubble release in one of these nooks and crannies and the pedal may get spongy again. You may have to bleed them, today, two or three times to get that good firm pedal. So be patient. Use clean fluid, follow the manufacturer's specifications. Just make sure the car is safe to drive no matter what bleeding procedure you use.