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Dan
Dan, Auto Technician
Category: Chevy
Satisfied Customers: 3490
Experience:  GM Mark of Excellence/ Service Guild Participant with 13 years experience, ASE Master Certified
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cant get all the air out of my brake system after bleeding

Resolved Question:

can't get all the air out of my brake system after bleeding all wheels brake light still comes on. This happened after i replaced the master cylinder. I have a 96 corvette
Submitted: 5 years ago.
Category: Chevy
Expert:  Dan replied 5 years ago.
Did you bench bleed the master cylinder before installing on the car?
Customer: replied 5 years ago.
Idid bench bleed my master cylinder before I put it on is there any thing else i can do
Customer: replied 5 years ago.
Relist: I still need help.
Expert:  Dan replied 5 years ago.

Try these procedures and let me know if they work ok.

 

Hydraulic Brake System Bleeding (Manual)

The time required to bleed the hydraulic system can be reduced if the master cylinder reservoir is filled with brake fluid and as much air as possible is expelled before the master cylinder is installed on the vehicle. Pumping the piston can evacuate the air from the piston cavities.

Power brakes require the vacuum reserve be depleted by applying the brakes several items with the engine off. Care must be taken to prevent brake fluid from contacting any painted surface. Use rags to catch the excess fluid.


    Object Number: 171922  Size: SH
    Click here for detailed picture of above image.
  1. Fill the master cylinder reservoir with brake fluid and keep the reservoir at least half full of fluid during the bleeding operation.

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  2. If the master cylinder is known or suspected to have air in the bore, then it must be bled in the following manner, before bleeding any caliper:
    2.1. Disconnect the forward (blind end) brake pipe connection at the master cylinder.
    2.2. Allow the brake fluid to fill the master cylinder piston bore until it begins to flow from the forward pipe connector port.
    2.3. Connect the forward brake pipe to the master cylinder and tighten.
    2.4. Depress the brake pedal slowly one time and hold. Loosen the forward brake pipe connection at the master cylinder to purge air from the bore. Tighten the connection and then release the brake pedal slowly. Wait 15 seconds. Repeat the sequence, including the 15 second wait, until all air is removed from the bore.

    Tighten
    Tighten the brake pipe tube nut to 18 N·m (13 lb ft).

    2.5. When clear fluid flows from the forward connection, repeat steps 1 and 2 to bleed the master cylinder at the rear (cowl) connection.

    Object Number: 63934  Size: SH
    Click here for detailed picture of above image.
  3. Individual brake calipers are bled only after all air is removed from the master cylinder. If it is known that the brake calipers do not contain any air, then it will not be necessary to bleed them.
    3.1. Place a proper size box end wrench, or equivalent, over the brake caliper bleed screw. Attach a clear tube over the screw. Submerge the other end of the tube in a clear container partially filled with brake fluid.
    3.2. Depress the brake pedal slowly one time and hold. Loosen the brake caliper bleed screw to purge the air from the cylinder. Tighten the brake caliper bleed screw and slowly release the pedal. Wait 15 seconds. Repeat the sequence, including the 15 second wait, until all air is removed. It may be necessary to repeat the sequence 10 or more times to remove all the air. Rapid pumping of the brake pedal pushes the master cylinder secondary piston down the bore in a way that makes it difficult to bleed the system.

    Tighten
    Tighten the brake caliper bleed screws to 12 N·m (106 lb in).

    3.3. If it is necessary to bleed all of the brake calipers, the following sequence should be used:
    3.3.1. Right rear
    3.3.2. Left rear
    3.3.3. Right front
    3.3.4. Left front
    3.4. Check the brake pedal for sponginess.
    3.5. Auto bleed the modulator and repeat the manual bleeding procedure to correct this condition. Refer to Antilock Brake System Automated Bleed Procedure in ABS.

Antilock Brake System Automated Bleed Procedure

First perform a manual or pressure bleeding procedure. Refer to Pressure Bleeding in Hydraulic Brakes. If the desired brake pedal height results are not achieved, perform the auto bleed procedure below.

The auto bleed procedure is used on Delco Bosch 5 equipped vehicles. The procedure cycles the system valves and runs the pump in order to purge the air from the secondary circuits normally closed off during non ABS/TCS mode operation and bleeding. The auto bleed procedure is recommended when air ingestion is suspected in the secondary circuits, or when the BPMV has been replaced.

Items Required

A scan tool
A 30 psi adapter equipped brake bleeder
Delco Supreme 11 brake fluid
A hoist
An unbreakable plastic bleeder bottle equipped with a hose
An assistant
The suitable safety attire, including safety glasses

Auto Bleed Procedure

    Notice: The Auto Bleed Procedure may be terminated at any time during the process by pressing the EXIT button. No further Scan Tool prompts pertaining to the Auto Bleed procedure will be given. After exiting the bleed procedure, relieve bleed pressure and disconnect bleed equipment per manufacturers instructions. Failure to properly relieve pressure may result in spilled brake fluid causing damage to components and painted surfaces.

  1. Raise the vehicle on a suitable support.
  2. Remove all four tire and wheel assemblies.
  3. Inspect the brake system for the following conditions. Repair or replace as needed:
    Leaks
    Visual damage
  4. Inspect the battery state of charge.
  5. Connect the scan tool to the DLC.
  6. Turn the ignition to ON position with the engine off.
  7. Using the scan tool, establish communications with the ABS/TCS system.

    Select the following features:

    ABS/TCS
    Special Functions
    AUTOMATED BLEED PROCEDURE
  8. Bleed the basic brake system. Refer to Pressure Bleeding in Hydraulic Brakes.
  9. Follow the scan tool directions until the desired brake pedal height is achieved.
  10. If the bleed procedure is aborted, a malfunction exists. Perform the following steps before resuming the bleed procedure:
    If a DTC is detected, refer to the appropriate DTC table.
    If the brake pedal feels spongy, perform the conventional brake bleed procedure again. Refer to Pressure Bleeding in Hydraulic Brakes.
  11. When the desired pedal height is achieved, press the brake pedal in order to inspect for firmness.
  12. Disconnect the scan tool.
  13. Install the tire and wheel assemblies.
  14. Inspect the brake fluid level.
  15. Road test the vehicle while making sure the brake pedal remains high and firm.

Hydraulic Brake System Bleeding (Pressure)

Tools Required

J 35589 Pressure Bleeding Adapter


    Object Number: 171934  Size: SH
    Click here for detailed picture of above image.
  1. Remove the master cylinder reservoir cap. Replace it with J 35589 .
  2. Charge the bleeder to 140-172 kPa (20-25 psi).
  3. Connect the hose to J 35589 .
  4. Raise the vehicle and support. Refer to Lifting and Jacking the Vehicle in General Information.
    Object Number: 63934  Size: SH
    Click here for detailed picture of above image.
  5. If it is necessary to bleed all of the brake calipers, the following sequence should be used:
    5.1. Right rear
    5.2. Left rear
    5.3. Right front
    5.4. Left front
  6. Place the proper size box end wrench, or equivalent, over the brake caliper bleed screw. Attach a clear tube over the screw and allow the tube to hang submerged in a clear container partially filled with brake fluid.
  7. Open the brake caliper bleed screw at least ¾ of a turn and allow the brake fluid flow to continue until no air is seen in the brake fluid. Apply intermittent pressure to the brake pedal while pressure bleeding.

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  8. Close the brake caliper bleed screw.

    Tighten
    Tighten the brake caliper bleed screw to 12 N·m (106 lb in).

  9. Repeat steps 6 through 8 until all of the calipers have been bled.
  10. Lower the vehicle.
  11. Check the brake pedal for sponginess. Auto bleed the modulator and repeat the entire bleeding procedure to correct this condition. Refer to Antilock Brake System Automated Bleed Procedure in ABS.
  12. Remove the brake bleeding equipment from the master cylinder.
Dan, Auto Technician
Category: Chevy
Satisfied Customers: 3490
Experience: GM Mark of Excellence/ Service Guild Participant with 13 years experience, ASE Master Certified
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