Notes on externally invisible brake fluid loss - AH42.10-P-9406-02RT
WARNING: This page does not describe the selected car, but rather 199 other vehicles, including the 2020 Mercedes-Benz SLC300, 2020 Mercedes-Benz SL550, 2020 Mercedes-Benz SL450, 2020 Mercedes-Benz S65 AMG, and 2020 Mercedes-Benz GLA250. However, it is still accessible from the selected car via links, so may be relevant.
MODEL 251
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 master brake cylinder.
- Draw off any brake fluid which has entered and empty into a measuring beaker.
If there are more than 100 cm 3
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 poppet 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 cm 3
no brake fluid can reach the reaction disk or the poppet valve when the brake booster is installed.