When any part of the hydraulic system has been disconnected for repair or replacement, air may get into the lines and cause spongy pedal action (because air can be compressed and brake fluid cannot). To correct this condition, it is necessary to bleed the hydraulic system so to be sure all air is purged.
When bleeding the brake system, bleed one brake cylinder at a time, beginning with the left rear wheel cylinder first. ALWAYS Keep the master cylinder reservoir filled with brake fluid during the bleeding operation. Never use brake fluid that has been drained from the hydraulic system, no matter how clean it is.
The primary and secondary hydraulic brake systems are separate and are bled independently. During the bleeding operation, do not allow the reservoir to run dry. Keep the master cylinder reservoir filled with brake fluid.
- Clean all dirt from around the master cylinder fill cap, remove the cap and fill the master cylinder with brake fluid until the level is within 1 / 4 in. (6mm) of the top edge of the reservoir.
- Clean the bleeder screws at all 4 wheels. The bleeder screws are located on the back of the brake backing plate (drum brakes) and on the top of the brake calipers (disc brakes).
Attach a length of rubber hose over the bleeder screw and place the other end of the hose in a glass jar, submerged in brake fluid.
- Open the bleeder screw at least 1 full turn. Have an assistant slowly depress the brake pedal.
- Close the bleeder screw and tell your assistant to allow the brake pedal to return slowly. Continue this process to purge all air from the system.
- When bubbles cease to appear at the end of the bleeder hose, close the bleeder screw and remove the hose. Tighten the disc brake caliper bleeder screw to 11 ft. lbs. (15 Nm) and the drum brake wheel cylinder bleeder screw to 80 inch lbs. (10 Nm).
The correct brake system bleeding sequence is:
Left rear wheel
- Check the master cylinder fluid level and add fluid accordingly. Do this after bleeding each wheel.
- Repeat the bleeding operation at the remaining 3 wheels, ending with the one closet to the master cylinder.
- Fill the master cylinder reservoir to the proper level.