re: clutch disfunction -- sticking MC piston?

["Dan Hagrman" <dan@xxxxxxxx>]

Modelle,
I had (what I think is) the same thing happen when I put my engine in--the master clutch spring was not pushing the master piston all the way back out; it was sticking in the cylinder.  The clutch pedal returned to its normal position because it's sprung too, but as you pushed the pedal very slowly (by hand) you would feel it "engage" the piston partially down the stroke, at which point fluid resistance would occur.  The piston and pedal are not "attached"--if they were this would be much easier cause you could just pull up on the pedal.  I found if you felt for engagement with the piston,  "punched" the pedal down a half inch by flicking the pedal with your fingers and quickly letting go, you could "work" the piston all the way back. Bleeding is a very long process this way, since if the piston doesn't come back, it doesn't suck in new fluid.  

Don't bottom out the pedal while bleeding since if the pedal is against the firewall you can't "bump" out the piston again--when this happened I lightly banged on the clutch master cylinder with a hammer a few dozen times so the piston would come partially out again, allowing the "bump".  After several dozen times of me "bumping" the piston out and pressing back in I finally got it more or less kinda bled.  I'm driving it around in hopes use will loosen up the piston, allowing better bleeding.  Note the piston comes back fine when hydraulics are hooked up and the clutch pressure plate pushes fluid back into the master cylinder, but the master piston would stick when the slave cylinder bleeder screw was open (aka when bleeding).  My master clutch was pretty new when I started the rebuild 3 years ago, but was left open (no fluid) during the rebuild--bad idea in retrospect.
Hope this helps and good luck,
dan in kc, home of the former perpetual 2 liter rebuild http://kcaroc.pcbs.net/techses/89rebuild0/thumbs.asp

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