Wonky hydraulic clutch

I've got a Saab with a hydraulic clutch that intermittently gives me trouble shifting into first from a stop, only in town, and only when the car's warm. It seems like it's simply losing pressure. The heat variable, to me, suggests a bad slave (which is an annular type, if it matters), perhaps with some sort of internal leak?? The fact that it's only intermittent suggests that it's not air in the system. I'm not losing fluid; the slave and master are both dry. But I don't know what it is, and I don't want to install either a new slave to find out it's the master, or vice versa.

Is this in-town-intermittent-shifting-trouble-with-a-hydraulic-clutch scenario familiar to you, and if so, which end is the culprit?

I will be watching this thread closely. I am have THE EXACT same problem with the XJ Jeep. Ive changed the slave, bled like crazy and still no pedal response. Next is Master...

It sounds like an internal valve "gasket" --O-ring--problem failing. I'd guess it's the master; I think the slave would fully fail DUE to the heat.

by annular you mean inside the bellhousing and wrapped around the input shaft? so you basically have to do a clutch job to change it out?

ford used those on the f150s with the m50d manual trans and they were spotty at best. they never really worked exactly right and were made of plastic. the one that completely failed would slowly engage the clutch as you sat there with the pedal to the floor. others would just give seemingly random engagement/disengagement points and cause gear grinding.

edit: even with the spotty reliability of the slave cylinder on those, it was recommended to change out master and slave at the same time

I'd be a little surprised if it's the master cylinder. I had this same problem on a 1985 celica (only difficult to get in to 1st and only when hot). I replaced the master cyl. about 2k miles ago with a new one since it had an internal leak. I let the car sit for a few months and then started having this shifting problem. My fluid levels were fine and there were no external leaks.

Turns out my idle speed was set a bit higher than the factory spec (set at around 1000-1100 rpm) - I set it to about 700 rpm and the problem is pretty much gone. I do suspect that the slave is in kinda rough shape as well though since the car sat for about a decade before i purchased it, and I've had to replace all the other hydraulics on the car.

Check your idle speed 1st and see if it's running high.

Strizzo wrote: by annular you mean inside the bellhousing and wrapped around the input shaft?

Yes, wrapped around the input shaft:

Strizzo wrote: so you basically have to do a clutch job to change it out?

Yep. It's not hard on a Saab 900 (gearbox doesn't have to be separated) but I'd rather not do it if I don't have to, and I'd rather not buy a $120 slave to find out I messed with the wrong end.

@JohnyHachi 6: Idle speed is stock 850 rpm, automatically controlled.

Just occurred to me: maybe a bad pilot bearing??

I have the inverse problem on my camaro. When cold for the first few shifts/miles first and third are a little tough to grab. Once up to temperature I usually don't have any problems. Another internal slave cylinder too.