AH42.10-P-9406-02RT Notes on Externally Invisible Brake Fluid Loss

AH42.10-P-9406-02RT Notes on externally invisible brake fluid loss

In the event of brake fluid loss which is not visible from outside, check whether there is brake fluid ingress into the brake booster through a leaking secondary seal in the tandem master brake cylinder:
^ Remove tandem master brake cylinder.
^ Draw off any brake fluid which has entered and empty into a measuring beaker.

If there are more than 100 cm3 of brake fluid in the brake booster, 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 plate valve in the master control unit. Brake fluid must therefore only be suctioned off when the brake booster is installed. Up to a quantity of 100 cm3 no brake fluid can reach the reaction disk or the poppet valve when the brake booster is installed.