Clean the brake line.
Caution: Brake pipes are coated with a plastic layer to protect against corrosion. If this layer is damaged, the pipes may rust. For this reason, do not clean the pipes with a wire brush, sandpaper or screwdriver.
Check the pipes from the master brake cylinder to the wheel brake cylinders with a portable lamp. The master brake cylinder is located in the engine compartment under the brake system expansion tank.
The tubes should not be bent or dented. There should be no areas covered with corrosion or with abrasions. Otherwise, replace the section of the tube up to the next connection.
Brake hoses connect tubes to the wheel brake cylinders on the moving parts of the car. They are made of a material that can withstand high pressure, but over time they can crack, swell, or be damaged by sharp objects. In such cases, they must be replaced immediately.
To detect possible damage, bend the hoses by hand. Do not twist the hoses. Observe the color markings on the hoses!
Turn the steering wheel left and right until it stops. The brake hoses should not touch any parts of the car.
The connection points of the brake hoses and pipes must not be wet with brake fluid.
Note: If the expansion tank and gaskets are wet, this does not indicate a defective master cylinder. It is more likely that brake fluid is leaking through the vent in the tank cap or through the cap gasket.