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Home >> Subaru >> 2021 >> WRX Base >> Repair and Diagnosis >> External Pages >> Different car >> Section 17 (Brake System) >> Air Bleeding >> Procedure >> Brake Line
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Brake Line

WARNING: This page is about a different car, the 2022 Subaru WRX. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION:
  • During the operation, remove the fuse of electric brake booster from the sub fuse box to prevent the electric brake booster from starting. (Electric brake booster model) 
  • Do not let brake fluid come into contact with the painted surface of the vehicle. Wash away with water immediately and wipe off if it is spilled by accident. 
  • Do not mix different kinds of brake fluid. 
  • Do not allow water or foreign matter to enter the reservoir tank. 
  • Always use new brake fluid when replacing or refilling the brake fluid. 
  • During the operation, keep the reservoir tank filled with brake fluid at "MIN level" or higher to prevent entry of air. 
  • After air bleeding operation, wipe off the brake fluid around each bleeder screw and the reservoir tank. 
NOTE:

For convenience and safety, perform the work with 2 people. 

  1. Remove the fuse (a) of electric brake booster from the sub fuse box. (Electric brake booster model)
    NOTE:

    This operation is not required if the ground terminal is already removed from the battery sensor. 

    G14602282Courtesy of SUBARU OF AMERICA, INC.
  2. When the master cylinder assembly is replaced or the reservoir tank is empty, bleed air from the master cylinder assembly before bleeding air from the brake line. Ref. to BRAKE>AIR BLEEDING>PROCEDURE>MASTER CYLINDER .
  3. Add the brake fluid to the "MAX".
  4. Connect a transparent vinyl tube, etc. to the bleeder screw and a collection container.
    G13225428Courtesy of SUBARU OF AMERICA, INC.
  5. Loosen the bleeder screw, and then repeat the full stroke depressing operation of the brake pedal, until brake fluid in the tube has no more air bubbles.
    NOTE:

    Air bubbles are removed after repeating the depressing operation 15 times or more for the front caliper, and 20 times or more for the rear caliper. 

  6. Perform the steps  3 to  5 above on each brake caliper.
    NOTE:

    Perform in the order starting from the front RH → front LH → rear LH → rear RH. 

  7. Tighten the loosened bleeder screw, repeat firmly depressing of the brake pedal quickly 5 to 6 times, and then depress and hold the brake pedal.
  8. Loosen the bleeder screw to drain the brake fluid. When the brake pedal reaches the full stroke position, immediately tighten the bleeder screw and return the brake pedal.
  9. Repeat steps  7 and  8 until there are no more air bubbles in the tube.
  10. Perform the steps  7 to  9 above on each brake caliper.
    NOTE:

    Perform in the order starting from the front RH → front LH → rear LH → rear RH. 

  11. Perform the sequence control mode for the VDC Control Module & H/U in both ABS and VDC systems.
    CAUTION:
    • If there is a possibility that air enters the pressure control section in the VDC Control Module & H/U, perform steps   12  to   17 . 
    • For normal air bleeding operation, do not operate the sequence control for the VDC Control Module & H/U. (Operating the sequence control may let air in the normal air bleeding passages move to the pressure control section.) 
    NOTE:
    • Normal air bleeding operation does not help bleed air that enters the pressure control section in the VDC Control Module & H/U. 
    • If there is a possibility that air enters the pressure control section in the VDC Control Module & H/U (if ABS or VDC operates with air contained in the normal air bleeding passage), perform the sequence control mode for both of the ABS and VDC systems. 
  12. Perform the ABS sequence control mode. Ref. to VEHICLE DYNAMICS CONTROL (VDC)>ABS SEQUENCE CONTROL .
    CAUTION:

    Be sure to perform the ABS sequence control mode first. 

  13. Perform the air bleeding operation of steps  4 and  5 for the bleeder screw on each caliper.
    NOTE:
    • Perform in the order starting from the front RH → front LH → rear LH → rear RH. 
    • As a reference, the number of the full stroke depressing operation is six times. 
  14. Perform the VDC sequence control mode. Ref. to VEHICLE DYNAMICS CONTROL (VDC)>VDC SEQUENCE CONTROL .
  15. Perform the air bleeding operation of steps  4 and  5 for the bleeder screw on each caliper.
  16. Repeat steps  12 to  15 for three cycles.
  17. 17.  In case air still remains at step 16., repeat steps  12 to  15 again until all air is removed.
  18. Add the brake fluid to the "MAX".
  19. Tighten each bleeder screw to the specified torque.

    Tightening torque: 

    Front: 8 N.m (0.8 kgf-m, 5.9 ft-lb)

    Rear (except for the electronic parking brake model): 8 N.m (0.8 kgf-m, 5.9 ft-lb)

    Rear (electronic parking brake model): 17 N.m (1.7 kgf-m, 12.5 ft-lb)

  20. Install the bleeder cap to each bleeder screw.
  21. Install the fuse (a) of electric brake booster. (Electric brake booster model)
    NOTE:

    Perform this operation only when the fuse of electric brake booster is removed. 

    G14602282Courtesy of SUBARU OF AMERICA, INC.
  22. Check that the electric brake booster operates normally. (Electric brake booster model)
  23. Check that there are no brake fluid leaks at the flare nut portion or in the entire brake system.
  24. After inspection, wipe off the brake fluid around each bleeder screw and the reservoir tank.
  25. Perform a road test and ensure that the brakes operate normally.
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