Jaguar Brake Master Cylinder Failure
The master cylinder is the pump attached to your brake pedal that pushes the brake fluid through your system, causing the car to stop. When the master cylinder starts to fail, you'll notice the pedal sinking to the floor as you press on the pedal. Sometimes this failure is intermittent, and sometimes you won't notice it until you're sitting at a standstill holding the brakes. The pedal will start to sink to the floor as the fluid gets past the inner seals of the pump.
If you're really mechanically inclined and have a scrupulously clean place to work, you can replace the seals and save yourself money, but if you have any hesitation about your abilities, don't risk it. Brakes are too important to use as a learning tool. Get a new one.
See our Jaguar Parts Store Catalog to order parts.