Mk3 clutch slave cylinder problems

[VW<3]

Hi guys
Im having this weird problem with my cylinder
They are both practilly new (slave and master)
I removed the slave because it was making some noise and I greassed the end tip so it stops making
I already bled the circuit and the pedal felt hard and normal
But when I start driving specially on highways the pedal starts to feel soft....I mean it still works but its just builds pressure later

 

[alanack]

How did you bleed it?
I had no success manually bleeding mine. They only way i got it to bleed was with a reverse pressure bleeder

 

[VW<3]

Well the first time I did it it worked great and I did it like you do on the brakes
Except now it didnt work, it was still pushing the fork but the pedal felt soft
So I watched some videos and yes I found out the best way it is with the reverse pressure bleeder but I didnt have any similar tools
So I thought of something that was putting the end of a hose on the purge nut and other end on a reservoir I made filled with brake fluid
Than I pressed the pedal (the purge nut is loose) several times so fluid goes to the hose and fill it until it gets to the reservoir
So now even if there is some vaccum or whatsoever while tightening the purge nut it will grab brake fluid because the hose is filled with fluid so is the reservoir
After closing the purge nut I pressed several times and the pedal finally felt hard and good

 

[Nuje]

Gravity bleed works wonders a lot of the time.
Just fill up the reservoir, crack open the bleeder (with drain hose attached obviously), then go clean up some tools or something. Give it like 30minutes (just keep an eye on the reservoir and make sure it stays full).

I've done this a few times when I was struggling to get a good feel to the pedal and it's worked every time.

 

[Steve Addy]

Vacuum draw on the slave works well too.

Steve