Possibly this is due to air still in the system. It may or may not bleed itself out. Alternatively it might be due to a faulty slave cylinder, but I’d be mighty damn sure all the air was bled out before going after the slave.
THAT would be nice if it did!
In any case, I’ll be letting the mechanic know what happened. Is there a (further) bleeding procedure that he should perform or just try driving and it might bleed itself out?
I have seen cases where the air works out, but it’s not something I would rely on happening. Most often it’s in the form of a little bubble coming out of the master cylinder into its reservoir when the pedal is pressed down a bit then released. If you see bubbles when doing that (probably need an assistant, one person watches while the other presses the pedal), repeatedly press the pedal partway and release, in a slow rhythm, until no bubbles are seen for several strokes in a row.
Some vehicles are challenging to bleed thoroughly with the normal method of using the bleed screw at the slave cylinder – the air seems to get stuck somewhere and not move out. There is a special bleeding tool designed to bleed the system “backwards” – applying fluid under pressure at the slave’s bleed screw and pushing it (and any air) up into the reservoir. I also have had luck with applying vacuum to the top of the reservoir with a hand vacuum pump (have to fabricate a lid that seals at the top of the reservoir), which tends to draw stubborn bubbles out of the cylinder and lines.
Thank you Gary, that information is much appreciated and I’ll pass it on.
Some of those Japanese clutches can be hard to bleed entirely. I used to try and operate slave manually somehow in full strokes to get bled properly.
I put about 200 miles on it today and no issues. I’m cautiously optimistic.
I have also had luck on old British cars that were stubborn of pushing the pedal down, then wedging a broom stick to hold it there and leaving it overnight. The bubbles work their way up to the master and vent to the reservoir when the pedal is released the next day.
So. The pedal failed again and I dropped it to the mechanic. He bled it again, thoroughly, test drove it and seemed OK, but the next morning, still at the shop, it was leaking down again. At that point he was sure it was the slave cylinder so we went with a new clutch. All seems fine and I just wanted to give the (hopefully) final update and thank all that contributed advice and opinions. It’s much appreciated.