Mopar 4877429AC Brake Master Cylinder

Bench bleeding the master cylinder is important to expedite the bleeding of the entire hydraulic system after installation. To bench bleed, insert threaded plugs into the cylinder outlet holes, fill both reservoirs with brake fluid, and support the master cylinder level to prevent spillage. Loosen and tighten one plug at a time while pushing the piston assembly into the bore to expel air, preventing its return. Alternatively, you can remove the plug, depress the piston, and use your finger to seal the hole to prevent air from re-entering. Repeat this for both ports, stroking the piston three or four times for each outlet to ensure complete air removal. Refill the master cylinder reservoirs and install the cover assembly, being mindful not to overfill them.