Not the clutch again!

[mattatk]

Dear All,
I'm still having problems with my clutch. Earlier this year I fitted a new clutch (thanks Wayne for all the good parts & advice!).
When I bled the clutch the pedal stayed stuck to the floor. I tried pumping the clutch pedal with the pressure bleeder attached & managed to get the clutch pedal working partially ( I had to get my foot under it & pulling it back up after a gear change whilst driving).
Tried today to bleed the clutch again, this time I managed to get a bit of dirty fluid (debris flakes in the fluid) out very slowly (had 20psi on the motive bleeder). Then nothing came out. I tried various combinations of clutch pedal up, down & pumping (as it worked last time) to no avail. The clutch pedal remains stuck to the floor & no clutch operation?!

I am wondering if:
1. master cylinder has failed (no sign of leaks though)
2. save cylinder has failed (not sure why it would cause these symptoms)
3. clutch line is blocked with debris (what is the debris from ? corrosion?)
4......

Thanks in advance..

[mattatk]

OK update for anyone with clutch issues...

Tried to bleed again today & no joy. My wife came along & asked to help. I got her pumping the clutch so I could check the activity at the slave cylinder bleed. She was a bit rough with the pedal & slammed it to the stop, which forced out a blockage (maybe?) & we started to get a flow intermittently. I experimented with the pedal down (as recommended) & up. When the pedal was sitting up this time, fluid began to flow fast out the bleed nipple ?! Thinking of the flow diagram, it shouldn't happen. Pressing the pedal in, which should port fluid to the slave & bleed, stopped the flow. I pulled the pedal up again & it flowed freely, clearing out a few big bubbles.
Finished the bleed & car drove fine (although clutch initially wouldn't return the last few centemetres until a few minutes into the drive).
Problem appears to be solved but the clutch bleed with pedal up has totally confused me. Could the master cylinder be on the way out & leaking through an internal seal in the chamber?

[dad911]

Edit- Oops, I stand corrected, pedal should be depressed when pressure bleeding.

[JFP in PA]

Originally Posted by dad911

FWIW, I bleed the clutch with a pressure-bleeder(not pumping), pedal-up.

Which is incorrect, it should be bled with the pedal on the floor……….

[dad911]

Originally Posted by JFP in PA

Which is incorrect, it should be bled with the pedal on the floor……….

Thank you, I was wrong. Per Bentley and Factory Workshop manual, pedal should be depressed.

[mattatk]

Yes, which is why I posted this particular bleed... Nothing would come out of the slave bleed with pedal depressed (down) & pressure bleeder attached with 20psi, so out of despair I pumped the clutch pedal. Fluid began to flow freely when the pedal was raised?!
My understanding of the fluid flow is that with pedal raised fluid is ported back to the reservoir & when the pedal is depressed fluid is ported to the slave cylinder. For fluid to flow with pedal up, the piston (sleeve?) inside the master cylinder must be sticking or leaking internally.
Regardless, clutch works BEAUTIFULLY now...just wanted to pass on the info in case someone else ends up in a similar situation. If the master fails at a later date I'll let you know.
Cheers

[Wayne 962]

Here's my article where I discuss pressing in the pedal:

Pelican Technical Article: Clutch Hydraulics Overhaul (Master Cylinder & Slave Cylinder Replacement) - 986 Boxster (1997-04) - 987 Boxster (2005-08)

-Wayne

[a1ajfredj]

Car sat for 2 months outside with only a plug in slave supply, and prior to this it dripped a bit out.
Tried pressure, vac, and pump. No change. Tried your hint:
Kept pressure on, opened bleed and pumped pedal at same time.
Saw a bunch of foamy fluid come through catch line, and then repeated a few times.
All good now.
Thanks!