Clutch goes bye-bye with no leak - Problem 1 of 2

85K-ish on my '92 1.6L. New master cylinder, slave cylinder, and SS clutch line from 949Racing. Been bled 'til the cows come home. I have no loss of fluid but if I sit there with my foot on the clutch pedal it just goes away...

Impossible to pop it out of gear, have to shut the car down, pop it into neutral, start it back up and pump the clutch pedal a time or two and it behaves as advertised. As long as I put into neutral at stop lights, etc. everything is fine. Shifts perfectly (rebuilt shifter) and only acts up if I'm in a position of having to hold the clutch pedal down for even 15 seconds.

Thoughts?

The behavior sounds typical of air in the system. The question is where, and how is it getting in?

Have you checked within the boot on the slave cylinder? I had a slave cylinder that was going bad and would draw in air over time. I would bleed it and it would be fine for a month and then suddenly I'd have to bleed it again and there was never any fluid lost or apparent sign of leaks. Eventually it finally kicked the bucket and started leaking into the boot when it drew in air, but there was still no visual sign of a problem until I squeezed the boot and some of the collected fluid leaked out.

Another possibility is air in the master cylinder. I know that when I replaced mine, I had to pressurize the reservoir to fully bleed the master cylinder and get the air pockets pushed through the hard lines to the slave.

Quote:

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Originally Posted by Stoly

New master cylinder

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Did you bench bleed it? New MCs really like to trap air. Usually they require quite a lot of fluid circulated through by hand before you install. You can then reuse that fluid to bleed the rest of the system but yeah... I think this is your problem.

heat likes to ruin the seals . i had to replace a brake master that wasnt leaking.
double check all connections first.

same thing happened to me. what i had to do was actually adjust the clutch pedal. that was a few months ago and the car has been fine since. but your problem might be different comepared to what the other guys are saying...

Took me about 100 bleeds to fully purge my clutch system of air. It sounds like you still have air in the lines. I would try and bleed the hell out of it again.