E36 Clutch Trouble

My '94 325 randomly drops the clutch pedal to the floor when I go to engage it -- press it with my foot.
All I do is touch the pedal and it almost gets sucked down and stays about
an inch off of the floor. I can pull the pedal up with my toe, and then the clutch works fine again.
I've never experienced this behavior from a Master Cylinder, but that's where I think the problem is coming from.
The problem is very random and I can't find anything that causes the issue to occur. It just happens when it wants to, and the clutch works well the rest of the time. I can sit at a light with the pedal depressed and there is nothing to make me think that the MC is leaking fluid enough that the operation of the gear shifter is affected. (I always leave my car in N at a light, and select my gear when the light changes, so I do not stress the throw out bearing or the seals in the MC by holding the clutch depressed needlessly.)
Has anybody else ever had a clutch pedal simply fall to the floor when you go to use it?
I'm not considering mechanical failures, and I am stuck on fluid-related causes of the pedal behavior. If you can name a part that will give a random failure, I'd like to hear it.
If I can see straight, the clutch shares fluid with the brake system, is that correct? This would make me want to bleed the brakes after replacing the MC.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Air is getting into the system. Most popular cause are the seals in the master cylinder. It's possible for it to be bad seals in the slave cylinder, or the pedal adjustment to be off allowing the master cylinder piston to move too far out. It's also possible for it to be a leak in a line somewhere. But the master cylinder is the first thing to check.
Odds are you'll see fluid coming out of the end of the master cylinder... but even if not it can still be sucking in air. It's possible to just pinch off the supply line and change the piston without removing the cylinder itself, and that takes a fraction of the time of replacing the whole cylinder. --scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.