Base Brake System
NOTE: This bleeding procedure is only for the vehicle's base brakes hydraulic system. For bleeding the antilock brakes hydraulic system, refer to the Antilock Brake System Bleeding procedure.PRESSURE BLEEDING PROCEDURE
CAUTION: Before removing the master cylinder cover, thoroughly clean the cover and master cylinder fluid reservoir to prevent dirt and other foreign matter from dropping into the master cylinder fluid reservoir.
CAUTION: Use bleeder tank Special Tool C-3496-B with adapter Special Tool 6921 to pressurize the hydraulic system for bleeding.
CAUTION: When pressure bleeding the brakes hydraulic system the fluid reservoir filler neck must be removed from the master cylinder fluid reservoir. Failure to remove the filler neck from the fluid reservoir, may result in the filler neck separating from the fluid reservoir when the hydraulic system is pressurized.
Follow pressure bleeder manufacturer's instructions, for use of pressure bleeding equipment.
When bleeding the brake system, some air may be trapped in the brake lines or valves far upstream, as much as ten feet from the bleeder screw. Therefore, it is essential to have a fast flow of a large volume of brake fluid when bleeding the brakes to ensure all the air gets out.
1. Remove the filler neck from the master cylinder fluid reservoir.
2. Install the Adapter Master Cylinder Pressure Bleed Cap, Special Tool 6921 on the fluid reservoir of the master cylinder. Attach the fluid hose from the pressure bleeder to the fitting on Special Tool 6921.
3. Attach a clear plastic hose to the bleeder screw at one wheel and feed the hose into a clear jar containing fresh brake fluid.
NOTE: The following wheel sequence should be used when bleeding the brake hydraulic system. The use of this wheel sequence will ensure adequate removal of all trapped air from the brake hydraulic system.
- Left Rear Wheel
- Right Front Wheel
- Right Rear Wheel
- Left Front Wheel
4. Open the left rear wheel bleeder screw at least one full turn or more to obtain an adequate flow of brake fluid.
CAUTION: Just cracking the bleeder screw often restricts fluid flow, and a slow, weak fluid discharge will NOT get all the air out.
5. After 4 to 8 ounces of brake fluid has been bled through the hydraulic system, and an air-free flow is maintained in the hose and jar, this will indicate a good bleed of the hydraulic system has been obtained.
6. Repeat the procedure at all the other remaining bleeder screws. Then check the pedal for travel. If pedal travel is excessive or has not been improved, enough fluid has not passed through the system to expel all the trapped air. Be sure to monitor the fluid level in the pressure bleeder, so it stays at a proper level so air will not enter the brake system through the master cylinder.
7. Perform a final adjustment of the rear brake shoes and then test drive vehicle to be sure brakes are operating correctly and that pedal is solid.
BLEEDING WITHOUT A PRESSURE BLEEDER
NOTE: Correct manual bleeding of the brakes hydraulic system will require the aid of a helper.
NOTE: To adequately bleed the brakes using the manual bleeding procedure the rear brakes must be correctly adjusted. Prior to the manual bleeding of the brake hydraulic system, correctly adjust the rear brakes.
NOTE: The following wheel sequence should be used when bleeding the brake hydraulic system. The use of this wheel sequence will ensure adequate removal of all trapped air from the brake hydraulic system.
- Left Rear Wheel
- Right Front Wheel
- Right Rear Wheel
- Left Front Wheel
1. Pump the brake pedal three or four times and hold it down before the bleeder screw is opened.
2. Push the brake pedal toward the floor and hold it down. Then open the left rear bleeder screw at least 1 full turn. When the bleeder screw opens the brake pedal will drop all the way to the floor.
3. Release the brake pedal only after the bleeder screw is closed.
4. Repeat steps 1 through 3, four or five times, at each bleeder screw in the required sequence. This should pass a sufficient amount of fluid to expel all the trapped air from the brake system. Be sure to monitor the fluid level in the master cylinder, so it stays at a proper level so air will not enter the brake system through the master cylinder.
5. Perform a final adjustment of the rear brake shoes and then test drive vehicle to be sure brakes are operating correctly and that pedal is solid.
MASTER CYLINDER BLEEDING
CAUTION: When clamping master cylinder in vise, only clamp master cylinder by its mounting flange, do not clamp on primary piston, seal boot or body of master cylinder.
1. Clamp the master cylinder in a vise using only the mounting flange.
NOTE: Two different size bleeding tubes are used depending on which type of master cylinder the vehicle is equipped with. Vehicles equipped with traction control use a center port master cylinder with a 6 millimeter diameter brake tube. Vehicles not equipped with traction control use a compensating port master cylinder using a standard 3/16 inch diameter brake tube. Be sure the correct size bleeding tubes are used when bleeding the master cylinder.
2. Install the Bleeding Tubes, Special Tool 6920, for a non-traction control master cylinder or Special Tool 8129 for a traction control master cylinder on the master cylinder. Position bleeding tubes so the outlets of bleeding tubes will be below surface of brake fluid when reservoir is filled to its proper level.
3. Fill brake fluid reservoir with brake fluid conforming to DOT 3 specifications such as Mopar or an Equivalent.
4. Using a wooden dowel, depress push rod slowly, and then allow pistons to return to released position. Repeat several times until all air bubbles are expelled from master cylinder.
5. Remove bleeding tubes from master cylinder outlet ports, and then plug outlet ports and install fill cap on reservoir.
6. Remove master cylinder from vise.
7. Install the filler cap from the master cylinder filler neck, on the master cylinder fluid reservoir.
8. Install the master cylinder assembly on the power brake vacuum booster.
NOTE: It is not necessary to bleed the ABS Hydraulic Control Unit (HCU) after replacing the master cylinder. But, the base brake hydraulic system must be bled to ensure no air is entered the hydraulic system when the master cylinder was removed.