How to Bleed brakes on 2006 Chevrolet Cobalt ?

Manual Bleeding

1. Before servicing the vehicle, refer to the Precautions Section.
   
   WARNING

   When adding fluid to the brake master cylinder reservoir, use only GM approved or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container. The use of any type of fluid other than the recommended type of brake fluid may cause contamination which could result in damage to the internal rubber seals and/or rubber linings of hydraulic brake system components.
   
   
   
   WARNING

   Avoid spilling brake fluid onto painted surfaces, electrical connections, wiring, or cables. Brake fluid will damage painted surfaces and cause corrosion to electrical components. If any brake fluid comes in contact with painted surfaces, immediately flush the area with water. If any brake fluid comes in contact with electrical connections, wiring, or cables, use a clean shop cloth to wipe away the fluid.
2. Place a clean shop cloth beneath the brake master cylinder to catch brake fluid spills.
3. With the ignition OFF and the brakes cool, apply the brakes 3-5 times, or until the brake pedal effort increases significantly, in order to deplete the brake booster power reserve.
4. If you have performed a brake master cylinder bench bleeding on this vehicle, or if you disconnected the brake pipes from the master cylinder, or if you have disconnected the brake pipes from the proportioning valve assembly or the brake modulator assembly, you must perform the following steps to bleed air at the ports of the hydraulic component:
   1. If removal of the reservoir cap and diaphragm is necessary, clean the outside of the reservoir on and around the cap prior to removal.
   2. With the brake pipes installed securely to the master cylinder, proportioning valve assembly, or brake modulator assembly, loosen and separate one of the brake pipes from the port of the component. For the proportioning valve assembly or the brake modulator assembly, perform these steps in the sequence of system flow; begin with the fluid feed pipes from the master cylinder.
   3. Allow a small amount of brake fluid to gravity bleed from the open port of the component.
   4. Reconnect the brake pipe to the component and tighten securely.
   5. Have an assistant slowly depress the brake pedal fully and maintain steady pressure on the pedal.
   6. Loosen the same brake pipe to purge air from the open port of the component.
   7. Tighten the brake pipe, then have the assistant slowly release the brake pedal.
   8. Wait 15 seconds, then repeat steps 3-7 until all air is purged from the same port of the component.
   9. With the brake pipe installed securely to the master cylinder, proportioning valve assembly, or brake modulator assembly, and after all air has been purged from the first port of the component that was bled, loosen and separate the next brake pipe from the component, then repeat steps 3-8 until each of the ports on the component has been bled.
   10. After completing the final component port bleeding procedure, ensure that each of the brake pipe-to-component fittings is properly tightened.
5. Ensure the brake master cylinder reservoir remains at least half-full during this bleeding procedure. Add fluid as needed to maintain the proper level. Clean the outside of the reservoir on and around the reservoir cap prior to removing the cap and diaphragm.
6. Install a proper box-end wrench onto the RIGHT REAR wheel hydraulic circuit bleeder valve.
7. Install a transparent hose over the end of the bleeder valve.
8. Have an assistant slowly depress the brake pedal fully and maintain steady pressure on the pedal.
9. Loosen the bleeder valve to purge air from the wheel hydraulic circuit.
10. Tighten the bleeder valve, then have the assistant slowly release the brake pedal.
11. Wait 15 seconds, then repeat steps 8-10 until all air is purged from the same wheel hydraulic circuit.
12. With the right rear wheel hydraulic circuit bleeder valve tightened securely, and after all air has been purged from the right rear hydraulic circuit, install a proper box-end wrench onto the LEFT FRONT wheel hydraulic circuit bleeder valve.
13. Install a transparent hose over the end of the bleeder valve, then repeat steps 7-11.
14. With the left front wheel hydraulic circuit bleeder valve tightened securely, and after all air has been purged from the left front hydraulic circuit, install a proper box-end wrench onto the LEFT REAR wheel hydraulic circuit bleeder valve.
15. Install a transparent hose over the end of the bleeder valve, then repeat steps 7-11.
16. With the left rear wheel hydraulic circuit bleeder valve tightened securely, and after all air has been purged from the left rear hydraulic circuit, install a proper box-end wrench onto the RIGHT FRONT wheel hydraulic circuit bleeder valve.
17. Install a transparent hose over the end of the bleeder valve, then repeat steps 7-11.
18. After completing the final wheel hydraulic circuit bleeding procedure, ensure that each of the 4 wheel hydraulic circuit bleeder valves is properly tightened.
19. Slowly depress and release the brake pedal. Observe the feel of the brake pedal.
20. If the brake pedal feels spongy, repeat the bleeding procedure again. If the brake pedal still feels spongy after repeating the bleeding procedure, perform the following steps:
    1. Inspect the brake system for external leaks.
    2. Pressure bleed the hydraulic brake system in order to purge any air that may still be trapped in the system.
21. Turn the ignition key ON, with the engine OFF. Check to see if the brake system warning lamp remains illuminated.
    
    WARNING

    DO NOT allow the vehicle to be driven until it is diagnosed and repaired.

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