When the engine is off, I have a good brake pedal. With the engine running, the pedal sinks to the floor and the brakes hardly work. Is this a servo problem? The car is a 1974 Daimler limo
Theres nothing wrong with the servo as when the engine is running the servo applies extra power to your foot making the pedal go down, it is more likely to be air or a leak in the brake lines.