2001 Pathfinder air getting into clutch line

[RidgeRacer]

I have a 2001 Pathfinder - 2WD 5-speed.

I think air is getting into the clutch hydraulic system somehow. It will have a really hard clutch pedal, to the point of slipping sometimes. I can bleed the system and have it working fine, pedal feeling normal - clutch engaging halfway up in the pedal travel. But then after a day of driving, the pedal gets stiff again and the clutch engagement happens earlier and earlier in the pedal travel.

I don't see any fluid leaks and no fluid on the garage floor. Is it possible for the system to take on air somehow, but not leak fluid?

How would you guys recommend that I tackle this one?

Thank you!

[Chuck Tribolet]

By "earlier and earlier" do you mean "higher and higher" or "lower and lower".Air in the line will make it lower and lower.

[RidgeRacer]

Higher and higher I think. After I bled the clutch yesterday, the pedal felt 'normal' and the clutch would engage about halfway through the pedal travel.

By the time I got home this afternoon, the pedal felt stiff and the clutch would engage after maybe 1/8 of the pedal. If I don't bleed it again, within a day or two, it will feel like the clutch is slipping.

[Chuck Tribolet]

If you have air in the system, you have to compress the air before the clutchmechanism moves, so it engages lower, not higher.

My '01 PF clutch has always engaged near the top.

The FSM says set the height of the pedal pad 186-196mm above the metal(not carpet, not all the the other stuff) behind it, measured perpendicularly to the stuff behind it. Adjust the height using the pedal stopper, or, if you havecruise control, the ASCD cancel switch.

Then set the pedal free play (measured at the pedal) to 9-16mm. Adjust it byadjusting the length of the master cylinder push rod.

MMMM, I wonder if the lock nut on the master cylinder push rod is loose.

[RidgeRacer]

Maybe I am assuming air is the problem when it's something else...

There is pressure building in the hydraulic system somehow. I can bleed the system and adjust the pedal freeplay so that everything is as it should be. The locknut on that adjustment rod is tight.

But then when I drive the truck around for an hour or so, pressure builds up in the system such that I can feel the pedal getting stiffer and the clutch engages earlier and earlier to the point where it will feel like it's slipping if I let it go too long without bleeding it again.