Before changing the Brake Master Cylinder, you should first disconnect the ground cable of your car and then clean the exterior of the Brake Master Cylinder, particularly the cap and the fluid couplings. Remove the major working fluid tubes and cover the open ends of the tubes to prevent accumulation of dirt. If there is a wiring harness of a fluid level sensor, remove the wiring harness of the Brake Master Cylinder. Following that, the tubes connecting the brake fluid should be disconnected and to prevent entry of dirt, the ends should be covered. Unbolt the fire-wall or
Brake Booster if fitted and take the Brake Master Cylinder out of the vehicle. The Brake Master Cylinder assembly should be bench bled, then reinstalled into the vehicle when all brake hose connections have been made and the fluid level sender wiring if equipped. Pour brake fluid into the reservoir, continue to bleed the brake system and turn the brake system while doing so. DOT 3 brake fluid should be used since boiling will lead to brake failure. But brake pedal free play is determined by using an adjustable pushrod, and if the pushrod is not adjustable, shims are used. For bleeding, fitting the Brake Master Cylinder into a vise, connect two hoses on the outlets "fluid" into the tank, and pour brake fluid into the tank. Depress the pushrod with a wooden dowel a few times gently to eliminate the air from the mixture, then cap the outlets and take off the bleeding tubes. For overhaul, remove the Brake Master Cylinder assembly and clean all parts with clean brake fluid; the cylinder or piston should be replaced if the clearance is more than 0.15mm. During the assembly, grease all the parts with the new, clean brake fluid; you might also wish to use brake rebuilding kits for your convenience. Where more than skeptical about the condition of the overhaul, it is better to change the whole assembly for a new one.