You will see a white plastic retaining ring where the line connects to the transmission. Do not remove this, but instead push this in evenly toward the transmission while pulling the hydraulic line away from the transmission. One of Ford's "better ideas".
a leak in the pressure line could do it. are you sure the seals in the cylnders are good? Is the slave not holding pressure, or is the master not building pressure? How did you bleed it? it makes a difference. Also, if the master or slave cylinders weren't bench bled before installation, it can take a very long time to bleed all of the air out of the cylinders.
the slave cylinder is bad
Will it go into gear when the engine is off and the vehicle isn't moving? If so, it could be a problem with the pilot bearing or possibly the clutch slave cylinder wasn't installed properly. Check it for air bubbles. you may need to bleed the hydraulic line to the slave cylinder.
No, they break the first time you hit the clutch. They are there to help line up the slave cylinder push rod with the throw out arm.
Slave cylinder no bueno
If when the car is not running, you can put it in gear and the car will hold itself, it is most likely the slave cylinder on the transmission bad. Could be the master also, but the slave is much more likely to go out. Open the bleeder screw on the master and pump the clutch once. If fluid is pushed out, it is almost certainly the slave that is bad.
If you allowed the master/reservoir to drain empty while the line was disconnected or installed the master dry, you may have to remove the master and bench bleed it first. Always keep the reservoir full during the process.
Bad Oil sending unit.
check the slave cylinder,if its dry add fluid and then press the clutchin and out about 15 times
there are a few reasons why this can happen but the most likely is a problem with the slave cylinder
This sounds like it is the clutch itself, not the master or the slave. If you can put it in gear and it doesn't move, it has to be the clutch worn out. If it were the master or the slave, it would grind when you tried to put it in gear.
There wont be one on the master but there is one on the slave, it looks like a grease fitting.