GM: Electra/Park Avenue/Ninety-Eight 1990-1993

Filling and Bleeding

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SYSTEM FILLING



Checking and Filling

The fluid level must be maintained at the max mark on the master cylinder reservoir. A system operating properly and free of leaks should not need fluid added to it. The fluid level will appear to drop in the reservoir as the brakes wear, but will return to normal after brake linings are replaced. Adding fluid when not needed may result in fluid overflow.

Fluid may be added to either reservoir in normal fashion. The ignition must be off . Carefully wipe the reservoir cap and surrounding area free of dirt and debris before removing the cap. Use only dot 3 brake fluid from an unopened container. The use of dot 5 or silicone brake fluid is specifically prohibited in this system. Fill the reservoir only to the max mark; do not overfill. Make certain the reservoir cap is securely installed.

SYSTEM BLEEDING



Brake system bleeding is performed to remove air present in the lines or components. When a line is disconnected at a wheel, only that caliper and line must be bled. If a line is disconnected at a fitting between the master cylinder and a wheel, the brake system served by that line must be bled. Four wheel bleeding is required only if the lines are disconnected at the master cylinder or if air has entered due to a low fluid condition.


CAUTION
Do not move the vehicle until a firm brake pedal is obtained. An improperly bled system may cause reduced braking, collision or personal injury.

Manual Bleeding Procedure
  1. Remove the booster vacuum reserve by applying the brake pedal several times with the ignition off . The master cylinder must be free of air before bleeding the system. If the master cylinder contains air, it must be bled.
  2.  
  3. Loosen the forward (secondary) brake line connection at the master cylinder. Allow fluid to flow from the connection; maintain the fluid level in the reservoir.
  4.  
  5. Tighten the fitting at the master cylinder, stopping the flow of fluid.
  6.  
  7. Have an assistant depress the brake pedal slowly one time and hold the pedal down. Loosen the forward fitting again, purging air from the cylinder bore. Tighten the fitting, then release the pedal slowly.
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  9. Wait 15 seconds. Repeat Steps c and d , including the 15 second pause, until all air is removed from the bore.
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  11. Tighten the fitting to 15 ft. lbs. (20 Nm).
  12.  
  13. Repeat the entire procedure, Steps a through f , at the rearward (primary) brake line fitting.
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  15. Maintain the correct fluid level in the reservoir during the procedure. The reservoir must be tightly capped during bleeding to prevent fluid spray.
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  17. If more than one circuit is to be bled, do so in this order: right rear, left rear, right front and left front.
  18.  
  19. Remove the bleeder cap at the wheel to be bled. Fit a box-end wrench of the proper size over the bleed fitting. Attach a transparent hose to the fitting and immerse the other end of the hose in a clear container half-filled with clean brake fluid. The end of the hose must be submerged in the fluid at all times during the bleeding.
  20.  
  21. Depress the brake pedal slowly one time and hold it down. Loosen the bleeder valve to allow fluid and air into the hose and container. Tighten the bleeder, then slowly release the pedal.
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  23. Wait 15 seconds, then repeat Steps 5 and 6 until all air is removed. The sequence may need to be repeated many times to clear the entire circuit.
  24.  

Rapid pumping of the pedal will prevent satisfactory bleeding.

  1. When the circuit is free of all air, tighten the wheel cylinder bleed valve to 5 ft. lbs. (7 Nm) or tighten the caliper bleed valve to 10 ft. lbs. (13 Nm). Reinstall the cap on the bleed valve.
  2.  
  3. Repeat Steps 4-7 for each wheel to be bled.
  4.  
  5. Refill the master cylinder reservoir to the max line only.
  6.  
  7. Check the brake pedal for poor or spongy feel. Repeat the entire bleeding procedure if pedal feel is not correct.
  8.  

Pressure Bleeding Procedure

Use of a diaphragm pressure bleeder is required. The air chamber must be separated from the brake fluid to prevent entry of dirt and moisture. The correct bleeder adapter must be used to prevent damage to the reservoir.

  1. Fill the master cylinder reservoir to the proper level.
  2.  
  3. Install the bleeder adapter cap-J-35589 or equivalent-to the reservoir.
  4.  
  5. Pressurize the bleeder at 20-25 psi (140-172 kPa). Connect the bleeder pressure hose to the adapter on the reservoir; open the line valve on the bleeder.
  6.  
  7. If more than one circuit is to be bled, do so in this order: right rear, left rear, right front and left front.
  8.  
  9. Remove the bleeder cap at the wheel to be bled. Fit a box-end wrench of the proper size over the bleed fitting. Attach a transparent hose to the fitting and immerse the other end of the hose in a clear container half-filled with clean brake fluid. The end of the hose must be submerged in the fluid at all times during the bleeding.
  10.  
  11. Loosen the bleeder valve approximately 3 / 4 turn to allow fluid and air into the hose and container. Allow the fluid to flow until no air is seen in the fluid.
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  13. When the circuit is free of all air, tighten the wheel cylinder bleed valve to 5 ft. lbs. (7 Nm) or tighten the caliper bleed valve to 10 ft. lbs. (13 Nm). Reinstall the cover on the bleed valve.
  14.  
  15. Repeat Steps 5-7 for each wheel to be bled.
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  17. After all circuits are bled, close the pressure line valve on the bleeder. Disconnect the pressure bleeding equipment. Refill the master cylinder reservoir to the max line only.
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  19. Check the brake pedal for poor or spongy feel. Repeat the entire bleeding procedure if pedal feel is not correct.
  20.  

 
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