Brake Bleeding: Service and Repair
Caution: Do not move the vehicle until a firm brake pedal is obtained Air in the brake system can cause loss of brakes with possible personal injury.
Caution: Use only Delco Supreme II (GM P/N# 12377967) or equivalent DOT 3 brake fluid from a clean, sealed container. Do not use fluid from an open container that may be contaminated with water. Improper or contaminated fluid could result in damage to components, or loss of braking, with possible injury.
Caution: Do not overfill the brake fluid reservoir. Overfilling the brake fluid reservoir may cause the brake fluid to overflow onto the engine exhaust components during brake system service. The brake fluid is flammable and may cause a fire and personal injury if the brake fluid contacts the engine exhaust system components.
Notice: If any brake component is repaired or replaced such that air is allowed to enter the brake system, the entire bleeding procedure must be followed.
Notice: Avoid spilling brake fluid on any of the vehicle's painted surfaces, wiring, cables, or electric connectors. Brake fluid will damage the paint and the electrical connections. If any fluid is spilled on the vehicle, flush the area to lessen the damage.
A bleeding operation is necessary in order to remove air when air is introduced into the hydraulic brake system.
Bleed the hydraulic system at all four brakes if air has been introduced through a low fluid level or by disconnecting brake pipes at the master cylinder. If a brake hose or brake pipe is disconnected at one wheel, bleed only that one wheel caliper. If brake pipes or hoses are disconnected at any fitting located between the master cylinder and the brakes, then only bleed the brake system served by the disconnected pipe or hose.
Pressure Bleeding
- Tools Required
- J 29532 Diaphragm Type Brake Bleeder
- J 35589 Compact Brake Bleeder Adapter
Notice: Pressure bleeding equipment must be of the diaphragm type. It must have a rubber diaphragm between the air supply and the brake fluid to prevent air, moisture, and other contaminants from entering the hydraulic system.
1. Clean the brake fluid reservoir cover and the surrounding area.
2. Remove the brake fluid reservoir cover.
3. Inspect the brake fluid reservoir level. Refer to Master Cylinder Reservoir Filling.
Add clean brake fluid as required.
4. After making sure tank valve is off, to prevent spray of fluid from air pressure in the line. Connect the J 35589 to the brake fluid reservoir.
5. Adjust the pressure bleed equipment to 35 - 70 kPa (5 - 10 psi).
Important: Use a shop cloth to catch escaping brake fluid. Also, do not allow brake fluid to contact any painted surfaces as surface damage will occur. If brake fluid does contact any surface, flush surface with water to lessen damage.
6. If equipped with ABS, bleed the brake modulator brake pipe connections at mc1 and mc2 only using pressure bleeding equipment that is connected and pressurized:
6.1. Slowly open the brake pipe tube nuts on the brake modulator. Inspect for air in the escaping fluid.
Notice: Refer to Fastener Notice in Service Precautions.
6.2. When the air flow ceases, immediately tighten the tube nut.
- Tighten the tube nut to modulator 15 Nm (11 ft. lbs.).
7. Raise and suitably support the vehicle. Refer to Vehicle Lifting.
Important: The brakes must be bled in the sequence indicated.
1. Right rear
2. Left front
3. Left rear
4. Right front
Important: Ensure that the bleeder valves do not leak.
8. Perform the following steps in order to bleed the wheel brakes in the sequence shown indicated.
8.1. Attach a clear plastic bleeder hose (3) to the bleeder valve at the wheel.
8.2. Submerge the opposite hose end in a clean container (2) partially filled with clean brake fluid.
8.3. Slowly open the bleeder valve and allow the fluid to flow.
8.4. Close the valve when the fluid begins to flow without any air bubbles. Tap lightly on the caliper (1) in order to dislodge any trapped air bubbles.
- Tighten the front caliper bleeder valves to 13 Nm (115 inch lbs.).
- Tighten rear wheel cylinder bleeder valves to 7 Nm (62 inch lbs.).
9. Bleed air pressure from tank to avoid fluid spill. Remove the pressure bleeding equipment, including the J 35589.
10. Lower the vehicle.
11. Inspect the brake fluid level in the reservoir. Fill the reservoir to the proper level if necessary.
12. Reinstall the brake fluid reservoir cap.
13. Turn the ignition to the RUN position, then turn off the engine.
14. Apply the brake pedal with moderate force and hold the brake pedal. Note the pedal travel and feel.
15. If the pedal feels firm and constant and pedal travel is not excessive, start the engine. With the engine running, re-check the pedal travel.
16. If the pedal travel is still firm and constant and pedal travel is not excessive, perform a road test on the vehicle. Make several normal (non-ABS) stops from a moderate speed in order to ensure proper brake system function. Allow adequate cooling time between stops.
17. If pedal travel feels soft or has excessive travel either initially or after the engine start, do not drive the vehicle. Re-bleed the brake system.
18. Perform a road test on the vehicle. Make several normal (non-ABS) stops from a moderate speed in order to ensure proper brake system function. Allow adequate cooling time between stops.
Manual Bleeding
Important: In the following procedure, use a suitable container and/or shop cloths in order to catch and prevent the brake fluid from contacting any painted surfaces.
1. Clean the brake fluid reservoir cover and the surrounding area.
2. Remove the brake fluid reservoir cover.
3. Inspect the brake fluid level. Fill the reservoir to the correct level if necessary.
4. Install the brake fluid reservoir cover.
5. Raise and suitably support the vehicle. Refer to Vehicle Lifting.
Important: The brakes must be bled in the sequence indicated.
1. Right rear
2. Left front
3. Left rear
4. Right front
Important: Ensure that the bleeder valves do not leak.
6. Perform the following steps in order to bleed the wheel brakes in the sequence indicated.
6.1. Attach a clear bleeder hose (3) to the bleeder valve at the wheel.
6.2. Submerge the opposite hose in a clean container (2) partially filled with clean brake fluid.
6.3. Open the bleeder valve.
6.4. Slowly depress the brake pedal.
Important: In order to assist in freeing the entrapped air, tap lightly on the caliper (1) in order to dislodge any trapped air bubbles.
6.5. Close the valve and slowly release the brake pedal.
- Tighten the front caliper bleeder valves to 13 Nm (115 inch lbs.).
- Tighten the rear wheel cylinder bleeder valves to 7 Nm (62 inch lbs.).
7. Lower the vehicle.
8. Remove the brake fluid reservoir. Fill the reservoir to the correct level if necessary.
9. Install the brake fluid reservoir cap.
10. Turn the ignition to the RUN position, then turn off the engine.
11. Apply the brake pedal with moderate force and hold the brake pedal. Note the pedal travel and feel.
12. If the pedal feels firm and constant and pedal travel is not excessive, start the engine. With the engine running, re-check the pedal travel.
13. If the pedal travel is still firm and constant and pedal travel is not excessive, perform a road test on the vehicle. Make several normal (non-ABS) stops from a moderate speed in order to ensure proper brake system function. Allow adequate cooling time between stops.
14. If pedal travel feels soft or has excessive travel either initially or after the engine start, do not drive the vehicle. Re-bleed the brake system.
15. Perform a road test on the vehicle. Make several normal (non-ABS) stops from a moderate speed in order to ensure proper brake system function. Allow adequate cooling time between stops.