2g Clutch Pedal fade - NEW CYLINDERS!

[gt4248a]

Hello all.
I recently changed both the master and slave cylinders for my clutch (the slave cylinder died). The car ran great for a few weeks. My wife drove the car for a week and reported that the pedal is staying down sometimes. So I check it out. Here is what I found:

-fluid level in reservior is unchanged at the MAX line.
-no fluid is present outside either cylinder.
-car drives fine under normal shifting.

BUT if you press the clutch pedal lightly, it will give and eventually fade down to the floor. (Car still in motion and in gear.) You can pull it back up with your foot and press it hard (like with a regular shift) and it works fine. I drove 100+ miles this weekend to a cabin in the mountains with no issues.

SO here's my theory:
The check valve in the master cylinder (to let in fresh fluid when needed) is too loose and/or not closing all the way. This would explain why at low pressures (lightly pressing the clutch pedal) you can make the pedal fade to the floor, and at high pressures (regular pressure on the pedal) it works fine.

Here's where I need help.
(1) do you think I'm right?
(2) if so, is this something that can be fixed/adjusted?
(3) do you think the master cylinder I got (OEM) was defective?

Any advice is more than welcome.

By the way, I threw away the old parts.

 

[Lordpaxin]

DID you remove the Tranny mounted clutch buffer mechanism?

it would be the hunk of crap between the master and slave cyls.

 

[romeen]

It sounds like you're already on the right track. Scroll about 3/4 of the way down to where it says 2G "Ghost Pedal":

http://www.roadraceengineering.com/clutchandflywheeltech.htm

 

[EclipseTrbo420A]

Just to be safe maybe bleed it again.

 

[gt4248a]

From the link above:

2G "Ghost Pedal"
On very light foot pressure on a 2Gthe pedal drops to the floor all by it's self. ?? Yes. The little rubber seal in the pic above gets a little nick in it or a piece of dirt under it. On a regular pedal push, the seal seals fine and the clutch works normally. On a very light push, the seal does not seal well and fluid will bypass it. Since the 2Gs have a heavy assist spring, the additional assist is enough pressure to keep the pedal going towards the floor all alone. Quite disturbing to watch. Replacing or rebuilding the master cylinder will fix this.

Thanks!