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

Model 166, 171, 172, 197, 204, 207, 212, 216, 218, 221, 230 

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:

• 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 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 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.