Bleeding/Refilling Hydraulic Brake Lines

At times, it is possible that brake fluid may leak out of your hydraulic system. This can result in spongy feeling brakes and loss of stopping power and responsiveness. This document shows how to purge unwanted air bubbles from your hydraulic system and refill it with brake fluid. The brake used in the example is a Magura HS-22.

1. Magura Mini-Service Kit (includes extra nipples, mineral oil, syringes, etc.)
2. Metric wrench set or cresent wrench
3. Metric allen wrench set

1. Insert two of the nipples into two flexible tubes included in the Magura Mini-Service Kit as shown below in Figure 1.
   
   Figure 1: Tubes with nipples inserted into 1 end

2. Rotate appropriate brake so that it is horizontal by loosening screw shown below in Figure 2.
   
   Figure 2: Screw to loosen to rotate brake horizontal

3. Remove bleeder bolt from slave brake on the rear as shown below in Figure 3. (click here if you need help identifying the slave side).
   
   Figure 3: Rear bleeder bolt removed

4. Remove bleeder bolt from front brake as shown below in Figure 4.
   
   Figure 4: Front bleeder bolt removed

5. Connect syringe to free end of clear tube. Dip nipple end of tube and fill syringe completely with mineral oil by pulling out plunger. Make sure that there are no bubbles in the syringe (this make require turning the syringe vertical and pushing out air and a little bit of oil).
6. In the rear slave brake where you removed the bleeder bolt, screw in the oil filled syringe as shown below in Figure 5.
   
   Figure 5: Syringe (filled with oil) screwed into rear slave brake

7. Screw in second nipple/clear tube into the front brake bleeder hole as shown in Figure 6. Put empty end of tube into mineral oil container.
   
   Figure 6: Front tube screwed into brake with free end in container

8. Push oil through system using syringe. You should see bubbles in the top tube. The bleeding is complete when you don't see any more bubbles coming out. Be sure not to depress the syringe all the way.
9. After bubbles have stopped coming out, unscrew top tube/nipple and screw bleeder bolt back. Before tightening bleeder bolt, continue to press syringe, you should see mineral oil drip out the top brake around the bleeder bolt. As you are pressing the syringe, tighten the top bleeder bolt. This prevents air from seeping back into system as you are tightening.
10. With top bleeder bolt tight, remove bottom tube from slave brake and screw back in bleeder bolt.
11. Check the brake by pumping it several times and holding it. Check for leaks in the system.