AH42.10-N-9406-02S Notes on Externally Invisible Brake Fluid Loss

AH42.10-N-9406-02S Notes on Externally Invisible Brake Fluid Loss


Where brake fluid loss is not visible, it should be checked whether brake fluid has entered the brake booster through a leaking secondary seal in the tandem master brake cylinder: In this case the tandem master brake cylinder must be removed and any ingressed brake fluid extracted and emptied into a measuring cup.

If there are more than 100 cm3 of brake fluid in the brake booster, components which are not resistant to brake fluid may be damaged and the brake booster must be replaced.

The power diaphragm in the brake booster is resistant to brake fluid, but not the reaction disk and the poppet valve in the master control unit. Brake fluid must therefore only be suctioned off when the brake booster is installed. Where there is less than 100 cm3 brake fluid in the brake booster for an installed brake booster, brake fluid will be unable to reach the reaction disk or the poppet valve.