Master Cylinder Disassembly

IMPORTANT: Reservoir cap and diaphragm can be removed and inspected without removing the master cylinder from the vehicle.





1. Remove master cylinder from vehicle.

NOTICE: Base brake master cylinder shown. ABS master cylinder procedure is similar.

2. Wipe reservoir cap clean, remove cap, and inspect reservoir cap and diaphragm for cuts, cracks, nicks, or deformation. Replace damaged parts.
3. Empty brake fluid from reservoir.

Fig. 2 Master Cylinder Retainer Clip Removal:

4. Remove brake fluid level switch.
5. Remove reservoir.

NOTICE: Be careful not to damage piston, bore, or retainer groove.

6. Remove retainer clip from end of master cylinder while depressing primary piston assembly (use wooden dowel to depress piston assembly).

Fig. 3 Master Cylinder Piston Removal:

7. Apply low-pressure, non-lubricated compressed air into upper brake fluid output port (at blind end of master cylinder bore). This will facilitate removal of the primary piston assembly, secondary piston with seals, as well as the spring and spring retainer.
8. Clean all parts in clean, denatured alcohol. Dry with unlubricated, low-pressure compressed air. Blow out all passages in cylinder body.
9. Inspect the following:
a. Pistons and seals for nicks, cuts, cracks, wear, or corrosion. Replace all worn or damaged parts.
b. Master cylinder bore for scoring or corrosion. If noted, replace master cylinder. Do not hone master cylinder bore. Also, no abrasives should be used in bore.