GM Lumina/Grand Prix/Cutlass Supreme/Regal 1988-1996

Bleeding the Brake System

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WARNING
The brake system MUST be bled after the hydraulic system has been serviced. Air enters the system when components are removed, and this air has to be removed to prevent a spongy pedal resulting in poor system performance.

The time required to bleed the system can be reduced by removing as much air as possible before installing the master cylinder onto the vehicle. This is called bench bleeding the master cylinder. Place the master cylinder in a vise or holding fixture, run tubing from the fluid pipe fittings to the reservoir, fill the cylinder with DOT 3 brake fluid and pump the brake pushrod until most of the air is removed from the master cylinder. Install the master cylinder onto the vehicle and bleed all four wheels.

Care MUST be taken to prevent brake fluid from contacting any automotive paint surface. Brake fluid can stain or dissolve paint finishes if not removed immediately. Clean the surface with soap and water immediately after the fluid has contacted the painted surface.

MANUAL BLEEDING

The procedure for bleeding the ABS system differs from this one. Refer to the section on Bleeding under ANTI-LOCK BRAKING SYSTEM head later in this section if working with on a vehicle equipped with ABS.

For those of us who are not fortunate enough to have access to a power bleeding tool, the manual brake bleeding procedure will quite adequately remove air from the hydraulic system. The major difference between the pressure and manual bleeding procedures is that the manual method takes more time and will require help from an assistant. One person must depress the brake pedal, while another opens and closes the bleeder screws.

  1. Fill the master cylinder reservoir with brake fluid and keep the reservoir at least half full during the bleeding operation.
  2.  
  3. If the master cylinder has air in the bore, it must be removed before bleeding the calipers. Bleed the master cylinder as follows.
    1. Disconnect the forward brake pipe at the master cylinder.
    2.  
    3. Fill the reservoir until fluid begins to flow from the forward pipe connector port.
    4.  
    5. Reconnect the forward brake pipe and tighten.
    6.  
    7. Depress the brake pedal slowly one time and hold. Loosen the forward brake pipe and purge the air from the bore. Tighten the brake pipe, wait 15 seconds and repeat until all air is removed.
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    9. When the air is removed from the forward brake pipe, repeat the same procedures for the rear brake pipe.
    10.  

  4.  
  5. Bleed the calipers in the following order, (right front, right rear, left rear, left front).
  6.  
  7. Install a box end wrench over the bleeder valve and connect a clear tube onto the valve. Place the other end of the tube into a container of new brake fluid. The end of the tube must be submerged in brake fluid.
  8.  
  9. Depress the brake pedal slowly one time and hold. Loosen the bleeder valve to purge the air from the caliper. Close the valve and release the pedal. Repeat the procedure until all air is removed from the brake fluid.
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  11. Do NOT pump the brake pedal rapidly; this causes the air to churn and make bleeding difficult.
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  13. After the calipers have been bled, check the brake pedal for sponginess and the BRAKE warning lamp for low fluid level.
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  15. Repeat the bleeding operation if a spongy pedal is felt.
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  17. Fill the reservoir to the MAX line.
  18.  

PRESSURE BLEEDING



The procedure for bleeding the ABS system differs from this one. Refer to the section on Bleeding under ANTI-LOCK BRAKING SYSTEM head later in this section if working with on a vehicle equipped with ABS.

For the lucky ones with access to a pressure bleeding tool, this procedure may be used to quickly and efficiently remove air from the brake system. This procedure may be used as a guide, but be careful to follow the tool manufacturer's directions closely. Any pressure bleeding tool MUST be of the diaphragm-type. A proper pressure bleeder tool will utilize a rubber diaphragm between the air source and brake fluid in order to prevent air, moisture oil and other contaminants from entering the hydraulic system.

  1. Install Pressure Bleeder Adapter Cap J 35589 or equivalent, to the master cylinder.
  2.  
  3. Charge Diaphragm Type Brake Bleeder J 29532 or equivalent, to 20-25 psi (140-172 kPa).
  4.  
  5. Connect the line to the pressure bleeder adapter cap, then open the line valve.
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  7. Raise and safely support the vehicle.
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  9. If it is necesary to bleed all of the calipers/cylinders, the following sequence should be used:

    Right rear
     
    Left front
     
    Left rear
     
    Right front
     

  10.  

  1. Place a proper size box end wrench (or tool J 21472) over the caliper/cylinder bleeder valve.
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  3. Attach a clear tube over the bleeder screw, then submerge the other end of the tube in a clear container partially filled with clean brake fluid.
  4.  
  5. Open the bleeder screw at least 3 / 4 of a turn and allow flow to continue until no air is seen in the fluid.
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  7. Close the bleeder screw. Tighten the rear bleeder screws to 62 inch lbs. (7 Nm) and the front bleeder screws to 115 inch lbs. (13 Nm).
  8.  
  9. Repeat Steps 6-9 until all of the calipers and/or cylinders have been bled.
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  11. Carefully lower the vehicle.
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  13. Check the brake pedal for sponginess. If the condition is found, the entire bleeding procedure must be repeated.
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  15. Remove tools J 35589 and J 29532.
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  17. Refill the master cylinder to the proper level with brake fluid.
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  19. DO NOT attempt to move the vehicle unless a firm brake pedal is obtained.
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