I have an 1989 Saab 900 Turbo, 178000 miles, original clutch. The clutch pedal is perfectly firm and high when the temperature is cool or cold. But in summertime, when the temperature goes above 80F, the clutch pedal engages only when it is pushed right to the floor. If I leave the car overnight, when it is cool in the morning the clutch pedal works perfectly again. Could this be caused by an air bubble in the clutch fluid which expands at higher temperature and causes the problem? Or is this a sign that the clutch is in general failure mode?