WARNING!  Always have the vehicle under inspection on level ground, in park with the emergency brake on. Always wear protective eyewear, gloves and necessary clothing before inspection or work begins. Never crank an engine over when anyone is near the battery or engine. Always have an operational fire extinguisher close by, obey all first aid instructions in the event of an injury. Never stand in front or behind a vehicle when cranked over or running. When engine is cranked over keep hands and clothing away from rotating components. Never move a car without proper brake pedal operation.

The brake master cylinder is the manual hydraulic pressure part of the brake system. The brake master holds hydraulic brake fluid that is used to actuate the brake system. Brake fluid flows through brake system components and then to the front brake caliper under pressure to slow the vehicle. When a master cylinder fails you may experience a low brake pedal, the master cylinder is divide into two separate sections, the primary and secondary pressure systems. This system was created inside the master cylinder for safety, if one half of the brake system fails you will still have the remaining half to help slow the vehicle. Note: You must know how to bleed a hydraulic brake system before you can service or change a master cylinder.

READ COMPLETELY BEFORE STARTING!

Step 1 - Identify brake master cylinder and reservoir

Identify brake master cylinder components, brake fluid cap, brake master cylinder, fluid lines, and brake fluid level sensor. Inspect for any brake fluid leakage around the master cylinder and check for proper fluid level regularly. If leakage is present replace master cylinder immediately.

Step 2 - Removing Brake Fluid

Remove brake fluid reservoir cap and insert brake fluid removal tool, remove as much brake fluid as possible. Then refill and reinstall brake fluid reservoir cap.

Step 3 - Removing the brake fluid level sensor connector

Remove the electrical connector to the fluid level sensor. Most connectors have safety clips that need to be released before they will disconnect.

Step 4 - Removing brake fluid lines

Install a line wrench firmly on the brake fluid lines departing from the master cylinder. A line wrench is a special wrench that holds five points of the fitting as opposed to two points like a normal wrench, which gives this special wrench more power without damaging the fitting than a normal wrench. Apply force to the wrench in a counter clockwise motion to loosen and remove fitting and line in the master cylinder. Repeat operation until all fluid lines are removed. Note: brake fluid will leak from brake lines when removed.

Step 5 - Removing master cylinder mounting bolts

Insert socket wrench onto master cylinder mounting bolts. After mounting bolts are removed, lift the master cylinder off the mounting studs and out of the vehicle.

Step 6 - Reinstall and bleed master cylinder system

Reinstall master cylinder, tighten master cylinder mounting bolts and reconnect the fluid lines and fluid level sensor. Refill the master cylinder with new fluid most cars use DOT3 or DOT4 but you should consult the cap on the master cylinder or your owner's manual. Once the master cylinder is full loosen all four brake fluid bleeder screws on the brake caliper or wheel cylinder. Next, press the brake pedal down completely, while holding the brake pedal down have a helper close all four brake bleeder screws. Now allow the brake pedal to return to normal position slowly, this will draw new fluid into the master cylinder body. Continue this procedure until the brake fluid is clean with no air bubbles out of each bleeder, close all bleeders and refill the master cylinder with brake fluid to the proper level.