Yes Master, Good Slave, temp sensitive clutch problems

[Peter Kirby]

non-returning clutch pedal

I agree with John: likely the master cylinder.  My 1990 20v90 had th same
symptom.  We guessed, and changed the slave cylinder but there was no
change -- the pedal would not always come up by itself.  We then put in a
used master.  The pedal then back by itself (although 6 months later, the
pedal is starting to feel a little sticky -- why didn't I put in a new
one???).

I took the old master apart.  Inside, where there should have been either
one or two return springs, there were at least three, all with razor-sharp
broken ends.  The return spring(s) had broken and were no longer able to
return the piston/pedal to its normal location.

Changing the clutch master is not too bad (on the 90).  We did have trouble
rethreading the hydraulic line onto it, but we (previous owner) eventually
got.    You do however have to go through the regular, under-dash
gymnastics.

BTW, the older master didn't leak a drop.

Peter