Master Cylinder Fluid Loss

DIAGNOSIS AND TESTING - MASTER CYLINDER FLUID LOSS
In case of brake fluid loss which is not visible, it should be checked whether brake fluid has entered the brake booster through a leaking secondary seal in the master brake cylinder:

1. Remove master brake cylinder.
2. Visually inspect the inside of the brake booster for traces of brake fluid.
3. Replace the brake booster if brake fluid is present.