B. Replace Master Cylinder

1. With the engine off, pump the brake pedal until a firm pedal is achieved (4-5 strokes).

CAUTION:
Vacuum in power booster must be pumped down before removing master cylinder to prevent booster from sucking in any contamination.





2. Remove vehicle wiring harness connector from brake fluid level sensor (Figure 2).





3. Disconnect the primary and secondary brake tubes from master cylinder housing (Figure 3). Install plugs at both open brake tube outlets.

Note:
Clean brake tube connections and master cylinder to booster area with a suitable brake cleaner before disconnecting tubes.





4. Remove the 2 nuts attaching the master cylinder to the power brake vacuum booster and slide the master cylinder straight out of the booster (Figure 4).





5. Remove the vacuum seal located in the front of the power brake vacuum booster by carefully inserting a small screw driver between the push rod of the power brake vacuum booster and vacuum seal. Then pry seal out of the booster (Figure 5).

Caution:
Do NOT attempt to pry seal out of power brake vacuum booster by inserting a tool between the seal and the brake booster.





6. Clamp the provided master cylinder in a vise and attach Bleeding Tubes, Special Tool 6802 to the master cylinder (Figure 6). Position tubes so outlets of Bleeding Tubes will be below surface of brake fluid when reservoir is filled to the proper level.

7. Fill brake fluid reservoir with brake fluid conforming to DOT 3 specifications such as Mopar or an equivalent.

8. 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 (Figure 6).

9. Remove bleeding tubes from master cylinder outlet ports, plug outlet ports and install fill cap on reservoir. Remove master cylinder from vise.

Note:
It is not necessary to bleed the entire hydraulic system after replacing the master cylinder. However, the master cylinder must have been bled and filled prior to installation.

10. Make sure brake booster vacuum seal on master cylinder push rod is positioned with notches on vacuum seal pointing toward master cylinder housing, and that seal is seated against master cylinder housing (Figure 7). Remove plastic protector from master cylinder push rod.





11. Align push rod on power brake vacuum booster with master cylinder push rod and install the master cylinder straight onto the power brake unit mounting studs (Figure 4).

12. Install master cylinder mounting nuts and torque to 250 in-lbs (28 N.m).

13. Remove plugs and connect brake tubes to master cylinder primary and secondary ports (Figure 3). Then torque all tube nuts to 145 in-lbs. (17 N.m).

14. Connect brake fluid level sensor wiring connector (Figure 2).

15. Top off master cylinder reservoir as necessary. Start engine and pump brake pedal firmly several times to assure of proper pedal travel and feel. Then check the system for leaks.