Why is my clutch soft every morning?

Question

1988 Nissan pickup. New clutch master and slave cylinders. New brake fluid. Bled at master cylinder, slave cylinder. Also bled at mid point bleeding nipple. Clutch is fine until next morning when you have to pump it over and over. Only disengages clutch after vigorous pumping. Fluid not leaking inside, fluid not leaking in line, fluid not leaking at slave. No detectable fluid missing from master cylinder. Why do I have to pump it in the morning? I am baffled.

Answer 1

Make sure everything is sealed good. If you paid to have it done, advise them of the problem, could be a bad seal or a bad master cylinder.

(1st guess)

Answer 2

Does NEW mean new, or rebuild? If new, I would expect correctness.

Possible problems are air being drawn in past the seal in the slave, or past the recoup seal in the master. Or....

Is there a spring helping the return of the slave, that may have been omitted?

How about a spring returning the clutch pedal?

Is there an adjustment on the master cylinder actuating rod, or the pedal, that may have been adjusted improperly, and is not allowing the piston to fully return?

I don't specifically know the Nissan setup. I'm just speculating on possibilities.

A master cylinder must fully return when released.

A slave cylinder should return by reason of the clutch pushing back via the release bearing, but usually there is a spring to further move the release fork back so the release bearing is not spinning continually.

Take a critical look.