After not being driven for 2 weeks and then left on an inclined surface, I went to drive the 924s one morning and found that the clutch pedal hit the floor.
No fluid inside on the carpet and no fluid spotted inside the engine compartment.
Bleeding the clutch has proved quite difficult so far. First I tried the pedal pump method, but was unable to get this to work.
Next I consulted an online video for a similar BMW system where the mechanic injects fluid from the slave cylinder bleed screw -- this didn't work in the case of the 924s. The small bleed screw doesn't allow much fluid in, and is difficult to close effectively from underneath the car.
My next step is to pressurize the reservoir and drive the air out the slave cylinder bleed screw. Up to 20 psi is said to be safe for the master cylinder and slave cylinder seals. The trick is finding or making the appropriate cap that has an air-tight fitting for pressurization. I just ordered a generic cap from this source:
My plan is to drill a hole in the center of the cap, attach an air fitting (1/4 inch or 3/8 inch pipe thread, secured with epoxy or glue) and then pressurize the reservoir. The reservoir must be full and I should be ready to open and close the bleed screw to get this method to work. I have an assistant, and hopefully this process will work.
Update: It turns out that the clutch master cylinder seal had blown after all. There was no detectable fluid -- other that the fluid that I later spilled trying to fix the problem. In the end since I couldn't get the car to shift, I had to have it towed to the dealer and all parts replaced. [> $1000 to fix]
And I have a spare cap.
