Craftsman 20930 Operator's Manual

Contents

Many brake systems today feature Anti-Lockfunctions and electronic controls. Many of thesesystems use a high pressure electric pump to keepthe system pressurized. When bleeding or servicing,these systems require special procedures andcautions.• ALWAYS observe the following precautions whenservicing Anti-Lock brake system:• ALWAYS wear safety goggles when servicing highpressure brake systems.• ALWAYS depressurize the ABS system prior toadding fluid or attempting service or repair.• Unless instructed to by the manufacturer’sprocedure, NEVER open a bleeder valve orloosen a hydraulic line while the ABS systemis pressurized.• ONLY use recommended brake fluids. DO NOT usesilicone brake fluid in ABS equipped vehicles.• Always refer to an appropriate repair manual foradditional information on Anti-Lock brake systems.DEPRESSURIZING ANTI-LOCKBRAKE SYSTEMSAlways refer to the vehicle owner’s manual orappropriate service manual for additionalinformation on depressurizing procedure.The procedure will work on most Anti-Lock brakesystems. Ensure ignition switch is in the OFFposition or disconnect the negative battery cable.Pump the brake pedal 25 to 40 times. A noticeablechange is felt. Continue to pump the pedal a fewadditional times. This should eliminate most systempressure. Open fluid reservoir or brake linescarefully. Top off reservoir fluid and reconnectbattery cable when finished.BLEEDING ANTI-LOCK BRAKE SYSTEMSAlways refer to the vehicle owner’s manual orappropriate service manual for manufacturer’sbrake bleeding procedure. The front brakes onmost Anti-Lock brake systems may be bled in theconventional manner. Most hydraulic pump/pressureaccumulator units are fitted with a bleeder valvewhich must be bled when the system has lost fluid oris being replaced. Some vehicles require that the sys-tem be pressurized when the rear brakes are bled.Some automotive manufacturers use bleedingprocedures which require specialized equipment.BRAKE LINE BLEEDINGMost low and soft pedal problems are caused by airin the hydraulic lines, which requires bleeding of thehydraulic system. By using the pump with brakebleeding accessories, the system can be bled easily.Follow a wheel-to-wheel sequence beginning with thewheel closest to the master cylinder.The kit provides a simple, clean, and quick methodfor bleeding the fluid lines in the automotive brakesystem. The creation of a vacuum in the reservoirjar causes fluid to be drawn into the reservoir jar.It should be noted that a tiny stream of bubblesmay be noticed in the hose after all of the air is bledfrom the lines. This is caused by air seeping aroundthe threads of the loosened bleeder fitting andbeing drawn back through the fitting by the suctionof the pump. Once the air is removed from withinthe system, these tiny bubbles will in no wayjeopardize the bleeding operation, since they arepresent only at the fitting and do not enter thesystem. If you wish, you can put grease or Teflontape around the threads of the fitting to eliminatemost of the bubbles. The correct bleeding procedurefollows:1) Always make certain that the master cylinderreservoir is filled and that a supply of new, cleanbrake fluid of the proper type is on hand to top offthe reservoir as the fluid level drops during bleeding.Make sure that all the bleeding fittings are clean priorto beginning of the bleeding procedure.2) Bleed the hydraulic system in the following order:A) Master cylinder bleeder fittings, if equipped.If installing a new or rebuilt master cylinder,follow the bench bleeding procedure which follows.16BRAKE BLEEDING