Notes on externally invisible brake fluid loss - AH42.10-P-9406-02V
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 117, 156, 171, 172, 176, 190, 197, 204, 205, 207, 212, 216, 217, 218, 221, 222, 230, 231, 242, 246
MODEL 211, 219 with ADAPTIVE BRAKE (ABR)
In the 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. The master brake cylinder must be removed for the test.
- Extract any brake fluid which has entered and pour it into a measuring cup.
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. With a quantity of up to 100 cm 3
, no brake fluid can get to the reaction disk or poppet valve when the brake booster is installed.