Geo Prizm Clutch Mystery

I recently purchased a Geo Prizm '94 and the clutch went out immediately. I had the problem diagnosed and the master cylinder replaced. The clutch again days later went out with different symptoms. It shifts most of the time but every few shifts the clutch looses all resistance and won’t shift. My friend and I replaced the slave cylinder and the same exact symptom persists. Funny, when the car is running this problem occurs but when it’s off the shifter works fine… can’t imagine what this might be. Any ideas??

Either there’s still air in the hydraulics of the clutch, or a bad clutch master cylinder was installed.

Tester

When the “…clutch looses all resistance…”, is the clutch master cylinder reservoir still full? If all the fluid has leaked out, you have a leak somewhere else than the master cylinder or slave cylinder so check where the fluid is going.

I’m not loosing fluid anywhere. The master cylinder is brand new. Can’t imagine that I got a bad part, perhaps though. Plan to bleed the line again to rule out air in the line.

When you crawl under it, and your friend depresses the pedal, does the actuator shaft in the slave move? How far? You may have a failing pressure plate, in a car this old it would not be a big surprise.

How far should it move? If the pressure plate is shot…what does this mean??