Bleeding your brake system is a necessity when replacing any hydraulic brake component and is a very crucial step that will usually require an assistant. Follow along with our tech as he shows you how to make your VW stop safely. If you do not feel comfortable or capable of bleeding your brakes do not hesitate to take your car to a mechanic.
We start the brake bleeding process with the car up on jack stands at all four wheels, so that we can access the brake bleeder valve. We've only pulled the wheels off for visual assistance; you do not need to do that at home.
In the trunk, we go through and make sure that the brake fluid reservoir is full, before starting the brake bleeding process. We start the brake bleeding process off at the right rear, the farthest away from the master cylinder.
We've put together a simple brake fluid catcher, nothing more than a plastic water bottle with a piece of hose inserted through a little hole we drilled at the top of the cap. We have a hose running down into the bottle, it's best to use a clear hose but anything that fits the bleeder valve is fine. You want to have a small amount of brake fluid in the bottle before you begin. Making sure that the hose is actually submerged in the fluid. This will help you to see any air bubbles that may be present in the line when bleeding your brakes.
With the bottle in place underneath the wheel, and the hose on the bleeder valve screw, use a wrench, in this case it is going to be a 7millimeter, to open and close the screw. We're going to have an assistant pump the brake pedal about five or six times, while we have the screw tightened. We will tell them to hold on the pedal and while they are holding the pedal down, we will open or unscrew the valve about one quarter turn. It is very important that your assistant keeps the pedal down, whenever this bleeder valve is open. With the pedal down and the bleeder valve open, leave the bleeder valve open for a couple of seconds, then tighten and have your assistant pump the brake pedal again.
You want to do roughly 10 of these pump and hold cycles to make certain that there isn't any air in the right rear line before moving to the left rear wheel. When you're bleeding the brakes, keep an eye on the fluid that's coming into the bottle, especially while the valve is open. If there's any air in the lines, you will see bubbles coming from the hose. If there isn't any air, you should see the fluid level in the bottle rise slightly. In our case we didn't change the hydraulic lines in the rear so we're not going to see much air in the rear lines. Because there is air in the front lines, the master cylinder cannot build much pressure, so were not going to see a bunch of fluid rising drastically. The main thing is we're making sure that there is no air in the rear line.
When switching between wheels, you want to make certain to top off the brake fluid reservoir with fluid. At the left rear we're going to repeat the brake bleeding process again, and again we're not going to see any air bubbles. We should see the fluid rise just ever so slightly when the valve is open. With the left rear brake line bled, it's time to top off the brake fluid reservoir once again, then were going to move to the front right wheel.
Since we have replaced the front brake hoses and wheel cylinders on the front right, we're going to see a lot of air at first, when bleeding the brakes here. Keep doing the pump and hold cycles until you no longer see any air bubbles coming out of the line and you have a steady stream of fluid coming out with each opening of the valve. It's at the front right where your assistant might mention that the brake pedal actually feels like it's doing some work, giving them some resistance while they are pumping the brakes.
With all the air bled from the front right, top off the brake fluid reservoir again and bleed the front left brake line. With the left bled, make certain to top off the brake fluid reservoir and put the cap back on. At this point the pedal should be nice and firm. This cars braking system is now completely rebuilt and ready to stop the car safely.