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Audi A3: How to Replace Brake Line

A problem as small as a leaking brake line could affect your whole Audi A3's braking performance. Read on to learn how to replace a bad brake line.

By Bassem Girgis - March 23, 2016

This article applies to the Audi A3 (2004-2012).

A small leak in a small brake line in the Audi A3 could ruin your whole brake system. The problem is as much the fluid leaking out, as it's in the air going into the system. The brake system operates off of hydraulic pressure. When air goes into it, it immediately affects its performance and stopping power. If you feel like your brake pedal is spongy, and if you feel like it takes a much harder press on the pedal to stop the car, this means you have a brake leak. Before jumping into the next how-to, be sure to find out the source of the leak, and make sure it's the only bad brake line. After replacing the brake line, you will have to bleed the system. If you know which brake line is leaking, then read on to learn how to replace it, and what to do after replacing it.

Audi A3 How to Replace Brake Line

Materials Needed

  • Wrench
  • Rag
  • Bottle
  • Clear hose
  • Brake line
  • Brake fluid

Step 1 – Remove brake line

After you've located the bad brake line, have your rag handy and remove the brake line. Use your flare nut wrench to remove the line nut, and have your new line close by. The quicker you swap the lines, the less mess you will make. You can use your rag to plug your line, so it doesn't leak too much.

AUDI A3 A4 BRAKE LINE REPLACE REMOVE CHANGE HOW TO
Figure 1. Remove brake line.

Step 2 – Install new line

When you're installing the new line in place, be sure to route it the same way the old one was routed. You will have to use the same clamps that was being used by the old line. Align the line in place, then tighten the line's nut using your 10mm flare nut wrench. Be sure to clean all the brake fluid that spilled.

AUDI A3 A4 BRAKE LINE REPLACE REMOVE CHANGE HOW TO
Figure 2. Install new brake line.

Step 3 – Bleed the brakes

Use a clear hose and put it on the brake caliper's bleeder screw. Start at the caliper furthest from the master cylinder, and work your way towards it. That means passenger's rear, the driver's rear, passenger front and end with the driver's front brake caliper. Connect the other end of the hose to an empty bottle, then ask a friend to pump the brake pedal a few times. With the brake pedal pressed down, loosen the bleeder screw with your wrench, then watch the fluid coming out. Tighten the bleeder screw and have your assistant repeat pumping the pedal, holding it down and opening the bleeder. As soon as you stop seeing bubbles in the fluid, you are done. Make sure to refill the master cylinder with fluid between each caliper. If the fluid in the caliper gets too low, you will have to restart the process all over again.

  • AUDI A3 A4 BRAKE LINE REPLACE REMOVE CHANGE HOW TO
    Figure 3. Bleeder screw.
  • AUDI A3 A4 BRAKE LINE REPLACE REMOVE CHANGE HOW TO
    Figure 4. Bleed the brakes.

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