It's a hydraulic system with the clutch master cylinder on the back of clutch pedal in the engine bay, the slave cylinder is a carm unit which replaces the release bearing in the clutch is fed by the clutch master. the only way to detect a leak in the system is to do visual check from underneath the car. your looking for drips of fluids running down the bulk head from the master and a wet mating surface between the the gear box bell housing and the engine block. unfortunatley it's a 6 hr job to remove and replace the clutch so you may want to give to your local garage to do.
derek
February 2009