i have a 94 f350 with a 460 5 speed with the external slave on it. I put a new clutch,flyweel, throwout bearing, and pressure plate in the truck this spring and last year i installed a new clutch master cylinder, line and slave cylinder.

This year a couple of times it the clutch would get very hard to shift as it felt like i had no pedal pressure. them it would go back to normal.

It is back again and pumping the clutch pedal doesnt help. it tends to want to stay in gear even though the clutch is depressed and the fluid isnt leaking oranything.

could the master cylinder of gone out? or the slave be causing it?

 

it sounds like one of 2 things
1: still has air in system to remedy this pull the external slave let it hang. remove the cap and have a helper watch the fluid level and watch for bubbles. now manually push the push rod on the slave and repeat untill helper says no more bubbles.
2: see if there is any slop at the pedal/ clutch push rod going into master cylinder if there is play there you will get hard shifting go to part stores and look for an adjustable one or in my case i had to make my push rod longer i cut a bullet casing to length and tapped on the end of the rod that goes into master cylinder.

I almost guarantee one of both of these solutions will fix your problem i had the same problem and now i dont.

 

I just thought I'd repost something to put the thread back on the front page maybe get more input