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Home >> Subaru >> 2019 >> BRZ Limited, Automatic Trans >> Repair and Diagnosis (Single Page) >> Brakes >> Mechanical - Hydraulic >> Brake System (Hydraulic) >> Brake Fluid >> Air Bleeding

Air Bleeding

  1. Precautions for handling-procedures
    CAUTION:
    • Do not let brake fluid come into contact with the painted surface of the vehicle. If spilled, wash it off with water and wipe clean quickly.
    • Do not reuse drained brake fluid. When refilling, always use new brake fluid.
    • To prevent deterioration of brake fluid performance, do not mix different grades of brake fluid (even if they are same brand).
    • Do not allow dirt or dust to enter the brake master cylinder SUB-ASSY.
    • Work in pairs to work safely and easily.
    • During work, refill brake fluid frequently to over the MIN level to prevent the brake master cylinder reservoir ASSY from becoming empty, which prevents air entry.
    NOTE: For procedures of air bleeding in each part, refer to the following.
  2. Air bleeding of master cylinder
    NOTE:
    • When the brake master cylinder SUB-ASSY has been replaced, or the brake master cylinder reservoir ASSY is empty, bleed air from the brake master cylinder ASSY.
    • When air bleeding of the brake master cylinder SUB-ASSY is not necessary, omit the following procedure and bleed air from the brake line. (Refer to ON-VEHICLE INSPECTION )
    1. While pushing the brake tube against the brake master cylinder SUB-ASSY, press it until the tip of the flare-nut comes into contact with the back surface of the brake tube flare, and then tighten it.
      CAUTION: Be careful not to damage the inner wall of the brake tube flare.

      Standard value: T=19 N.m {194 kgf.cm} {14 ft-lb} 

      G12591028Courtesy of SUBARU OF AMERICA, INC.
    2. Fill the brake master cylinder reservoir ASSY of the brake master cylinder SUB-ASSY with brake fluid.
      NOTE:
      • Fill the brake fluid up to the MAX level.
      • During work, refill brake fluid frequently to over the MIN level to prevent the brake master cylinder reservoir ASSY from becoming empty, which prevents air entry.
    3. Install a transparent plastic tube to the bleeder screw of the right front caliper body ASSY, and install the other end of the tube to a recovery container.
    4. Loosen the bleeder screw, and then slowly depress the brake pedal and hold it.
    5. Tighten the bleeder screw, and then release the brake pedal quickly.
    6. Repeat the steps (4) to (5) until no air bubbles are seen in the brake fluid in the plastic tube.
      NOTE:
      • Repeat the steps six or seven times to get rid of air bubbles.
      • For the brembo type, perform in the order of inner →outer.
    7. Install a transparent plastic tube to the bleeder screw of the left front caliper body ASSY, and install the other end of the tube to a brake fluid recovery container.
    8. Repeat the steps (4) to (5) until no air bubbles are seen in the brake fluid in the plastic tube.
      NOTE:
      • Repeat the steps seven or eight times to get rid of air bubbles.
      • For the brembo type, perform in the order of inner →outer.
      • By performing steps up to here, air in the front brake piping passage and the front caliper is bled.

        Then perform the following procedure to bleed air which entered the rear brake piping passage and the rear caliper from the brake actuator ASSY.

    9. Install a transparent plastic tube to the bleeder screw of the left rear caliper body ASSY, and install the other end of the tube to a brake fluid recovery container.
    10. Loosen the bleeder screw and repeat depressing the brake pedal to full stroke slowly. Then tighten the bleeder screw repeatedly until no air bubbles are seen in the brake fluid in the plastic tube.
      NOTE:
      • For the brembo type, perform in the order of inner →outer.
      • By repeating the steps fifteen times or more, the air which entered the rear brake piping passage from the brake actuator ASSY reaches to the bleeder screw of the left rear caliper body ASSY, and then is drained.
    11. Install a transparent plastic tube to the bleeder screw of the right rear caliper body ASSY, and install the other end of the tube to a brake fluid recovery container.
    12. Perform the step (10).
      NOTE:
      • For the brembo type, perform in the order of inner →outer.
      • By repeating the steps ten times or more, the air which entered the rear brake piping passage from the brake actuator ASSY reaches to the bleeder screw of the right rear caliper body ASSY, and then is drained.
      • By performing steps up to here, air which entered the rear brake piping passage and the rear caliper body ASSY from the brake actuator ASSY is bled.

        Finally, perform the following procedure to bleed air which may remain in brake fluid stagnation areas.

    13. Install a transparent plastic tube to the bleeder screw of the right front caliper body ASSY, and install the other end of the tube to a brake fluid recovery container.
    14. Repeat depressing the brake pedal hard and quickly five or six times, and then hold the pedal depressed.
    15. Loosen the bleeder screw to drain brake fluid. When the brake pedal reaches the full stroke position, tighten the bleeder screw quickly, and then release the brake pedal.
    16. Repeat the steps (14) to (15) until no air bubbles are seen in the transparent plastic tube.
      NOTE: Repeat the steps four or five times.
    17. Repeat the steps (14) to (16) on each caliper body ASSY
      NOTE:
      • Perform air bleeding in order of the front RH→front LH→rear LH→rear RH.
      • For the brembo type, perform air bleeding in inner →outer in the order of front RH →front LH →rear LH →rear RH.
    18. Tighten each bleeder screw to the specified torque.
      1. Normal type

        Standard value: T=8 N.m {82 kgf.cm} {5.9 ft-lb} 

      2. Brembo type

        Standard value: T=20 N.m {203 kgf.cm} {14.8 ft-lb} 

    19. Install the cap bleeder to each bleeder screw.
      CAUTION: Remaining brake fluid inside and outside of the bleeder screw may cause misleading of damage to the painted surface and fluid leakage. Therefore, make sure to wipe off the brake fluid well after tightening.
  3. Air bleeding of brake line
    1. When the brake master cylinder SUB-ASSY has been replaced, or the brake master cylinder reservoir ASSY is empty, bleed air from the brake master cylinder SUB-ASSY before bleeding air from the brake line. (Refer to ON-VEHICLE INSPECTION )
      G12591029Courtesy of SUBARU OF AMERICA, INC.
    2. Fill the brake master cylinder reservoir ASSY of the brake master cylinder SUB-ASSY with brake fluid.
      NOTE: During work, refill brake fluid frequently to prevent the brake master cylinder reservoir ASSY from becoming empty, which prevents air entry.
    3. Install one end of a transparent plastic tube to the bleeder screw, and then install the other end of the tube to a brake fluid recovery container.
    4. Loosen the bleeder screw and depress the brake pedal to full stroke. Repeat it until no air bubbles are seen in the brake fluid in the transparent plastic tube.
      NOTE: Repeat the depressing operation fifteen times or more for the front caliper body ASSY and twenty times or more for the rear caliper body ASSY to get rid of air bubbles.
    5. Repeat the steps (2) to (4) on each caliper body ASSY.
      NOTE:
      • Perform air bleeding in order of the front RH→front LH→rear LH→rear RH.
      • For the brembo type, perform air bleeding in inner →outer in the order of front RH →front LH →rear LH →rear RH.
    6. Tighten the loosened bleeder screw and repeat depressing the brake pedal hard and quickly five or six times, and then hold the pedal depressed.
    7. Loosen the bleeder screw and drain the brake fluid. When the brake pedal reaches the full stroke position, tighten the bleeder screw quickly, and then release the brake pedal.
    8. Repeat the steps (6) to (7) until no air bubbles are seen in the transparent plastic tube.
    9. Repeat the steps (6) to (8) on each brake caliper.
      NOTE:
      • Perform air bleeding in order of the front RH→front LH→rear LH→rear RH.
      • For the brembo type, perform air bleeding in inner →outer in the order of front RH →front LH →rear LH →rear RH.
    10. Perform function inspection of both systems ABS and VSC.
      CAUTION:
      • If the entry of air into the pressure control part in the brake actuator ASSY may occur, perform the steps (11) to (16).
      • In the regular air bleeding, do not activate the function inspection of the brake actuator ASSY (The function inspection may cause air in the regular air bleeding passage to move into the pressure control part).
      NOTE:
      • The regular air bleeding cannot bleed air which entered the pressure control part in the brake actuator ASSY.
      • If the entry of air into the pressure control part in the brake actuator ASSY may occur (such as the case when the VSC or ABS was accidentally activated while air existed in the regular air bleeding passage), perform function inspection of both systems ABS and VSC.
    11. Perform the ABS function inspection. (Refer to FUNCTION INSPECTION )
      CAUTION: Always perform the ABS function inspection first.
    12. Perform the air bleeding (3) to (4) on the bleeder screw of each caliper body ASSY.
      NOTE:
      • Perform air bleeding in order of the front RH→front LH→rear LH→rear RH.
      • For the brembo type, perform air bleeding in inner →outer in the order of front RH →front LH →rear LH →rear RH.
      • The necessary number of the full stroke depressing operation is approx. six times.
    13. Perform the VSC function inspection. (Refer to FUNCTION INSPECTION )
    14. Perform the air bleeding (3) to (4) on the bleeder screw of each caliper body ASSY.
    15. Repeat the steps (11) to (14) three times.
    16. If the air is not bled completely in step (15), repeat the steps (11) to (14) until all the air is bled.
    17. Fill the brake master cylinder reservoir ASSY with brake fluid up to the MAX level.
    18. Tighten each bleeder screw to the specified torque.
      1. Normal type

        Standard value: T=8 N.m {82 kgf.cm} {5.9 ft-lb} 

      2. Brembo type

        Standard value: T=20 N.m {203 kgf.cm} {14.8 ft-lb} 

    19. Install the cap bleeder to each bleeder screw.
      CAUTION: Remaining brake fluid inside and outside of the bleeder screw may cause misleading of damage to the painted surface and fluid leakage.kage. Therefore, make sure to wipe off the brake fluid well after tightening.
    20. Check the flare-nut part or the entire brake system for brake fluid leakage.
    21. Perform the road test to confirm the brake works correctly.
  4. Air bleeding of brake actuator
    1. Bleed air from the brake line. (Refer to ON-VEHICLE INSPECTION )
      NOTE: If the entry of air into the pressure control part in the brake actuator ASSY may occur, perform function inspection of both systems ABS and VSC. (Refer to the steps for the brake line (10) to (16).)
  5. Air bleeding of caliper body ASSY
    1. Bleed air from the brake line. (Refer to ON-VEHICLE INSPECTION )
  6. Brake fluid leak check
  7. Brake fluid level check (Refer to ON-VEHICLE INSPECTION )
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