OK let's try again..Still need help..I have a 2000 Ford F-150 V6 5 speed you can crank drive and shift the truck fine for about 4 miles then the clutch pedal starts sticking..Let it cool off and you can go again till it gets hot again. Checked the master cylinder rod and it looks good..Is my problem in the master cylinder or the clutch slave cylinder

 

How old is the fluid? How clean is it?

 

since you say it is heat related, it would have to be the slave cylinder. The master cyl is remote and doesn't get hot by itself where it is, but the slave is at where heat is. Check the hose between them. Seen those go bad internally, just like a front brake hose, and block fluid from going thru, making what you are describing. Just a thought or two for you.

 

AK is absolutely right about the heat with the slave cylinder and hoses. Brake fluid though is hygroscopic except for Dot 5 which means it absorbs water. The older the fluid the more water it's absorbed which drastically lowers its boiling point. The water vapor released from boiling has various effects one of which can be sticking pedals. Replacing a slave cylinder is a lot of work that may be avoided with trying a fluid change first. I've seen slaves changed that fixed the problem but it was because of the new fluid that comes with installing a new cylinder.

 

I am not really familiar with the F150 setup with the throw out bearing.... but I've seen the bearing retainer/sleeve get worn down enough that the t/o bearing hangs up on it. The metal will expand and retract with temperatures.

 

at least it looks like it's a 2wd and since it's a v6, easy enough to drop the transmission to the ground.