Removal
Disconnect the electrical connector from the fluid level sensor located in the filler cap of the brake fluid reservoir. Remove the cap. Pump out the brake fluid from the reservoir.
Mark the brake pipes that go to the master cylinder. Unscrew the union nuts from the brake cylinder and disconnect the brake pipes. On vehicles equipped with the ABS system, when disconnecting the return pipes from the reservoir, press the lock against the reservoir and remove the pipe (see Fig. 9.40). Close the pipes with plugs.
Unscrew the nuts and remove the master cylinder from the vacuum booster.
Disassembly
Clean the outside surface of the master cylinder.
Clamp the master cylinder in a vice with soft jaws.
Remove the brake fluid reservoir from the top of the master cylinder by pulling it toward you.
Remove the reservoir seal ring from the top of the master cylinder.
Remove the snap ring from the groove at the rear of the master cylinder.
Pull the first piston out of the back of the cylinder along with the gasket, O-ring and steel washer.
Remove the second piston from the cylinder.
To disassemble the first piston and replace the sealing ring, remove the spring from the piston. Using a screwdriver, remove the retainer by the eye and the sealing ring (see Fig. 9.42, 9.43).
To disassemble the second piston, remove the spring, retainer and, using the same method as for the first piston, remove the sealing ring (see Fig. 9.44).
Wash all master cylinder parts in methylated spirits or clean brake fluid. Inspect the cylinder parts for wear and damage.
Lubricate the cylinder parts in brake fluid. Assemble each piston in the reverse order of disassembly. Check that the sealing rings are installed correctly and are securely fastened with clamps.
Lubricate the pistons and install them into the master cylinder by pressing and simultaneously rotating them around the axis. After installing the pistons into the cylinder, install the steel washer, new sealing ring, gasket and secure them with a retaining ring.
Installation
Clean the mating surfaces of the master cylinder and brake booster. Installation is performed in the reverse order of removal.