This came on all of a sudden. I've worn out many clutches before, and I don't believe that this is a case of a worn clutch (although it may indeed be worn). One day, I get in the car to drive & I press the clutch pedal and it goes all the way to the floor, with very little resistance. If I were to compare - it felt the same when bleeding brakes, when the valve gets released and the pedal sinks to the floor. Interestingly, if I pump the pedal a few dozen times, the pressure returns, and eventually I can use the clutch again, and it performs as normal. After the car has sat parked for an extended amount of time (10-12 hrs), then I discover it has lost all pressure again. In contrast, after only an hour or two of being parked, I can return to the car and there's no apparent loss of pressure.
I know the clutch is hydraulically manipulated, but I can find no leak of fluid anywhere (it might help if I knew of some place to look other than the ground beneath the car). Besides, I've been driving the car like this now for over a week (having to pump up the clutch before taking off), so I would think that if the problem were due to loss of fluid - as in, a leak - then I would be out of fluid at this point. Further, I don't see how the pressure could build back up if I have a leak of some sort (just my best guess). I'm wondering if what I'm experiencing is possibly the slave cylinder going bad?
Any help would be appreciated, as usual. Thanks!