1989 ford f150 4wd shifter disengages and gose in and out. If i put pressure on shifter and hold it it will work

Steve's right but the throw out bearing may be out of alignment as well as pressure plate and clutch disc also check the linkage for the shifter

If you look down in the top of the transmission where the shifter goes. You will see three parts. These parts are forks. There is a center slot in all three. The slots have to be lined up and in the center. This is neutral. Then the shifter can be installed.

Shift interlock solenoid not working and will not disengage parking lock, remove center console, locate shift solenoid, test it, if bad replace it. In the meantime you can use a zip lock tie to hold it in the disengaged position and your shifter should work.

IF you have bled the clutch system and managed to get a firm clutch then the clutch plate has been installed back to front and the clutch center is hitting the bolts that hold flywheel onto the crankshaft. If you have no not got a firm predal pressure replace the clutch master cyl

with the transmission in neutral,and on level ground try rocking the truck back and forth manually while working the shifterfor the 4 wheel..sometimes if too much pressure is mechanically on the drivetrain it will not shift at all..also check fluid lever in transfer case..low fluid will cause the shifter to bind up..good luck..

The pressure plate needs to be replaced...when working this allows the clutch to disengage, so you can manually change gears...Hope this helps.

The original shifter bush (shifter sheet) is made of nylon and after 20 years of sitting in oil they crumble away and disappear.
Replacement is cheap and easy.

Are the front hubs still locked in?

If you have manually locking front hubs, you probably have a bit of binding in the drive train due to the front wheels being locked to the drive system

After unlocking the hubs, back up about 20 feet, then back forward about 20 feet.....see then if the transfer case can then be disengaged. You MAY need to just yank on the transfer case shifter while the vehicle is moving (slowly of course).....

I had an older ford pickup which did the same thing.....disengaging the hubs and just yanking the shifter had disengaged the 4 wheel drive then I was able to put it back into 2wh high.

Ok, I guess its going to be a not too obvious solution then. All we have to do is find it...
1.What type of gear shifter is in your truck. Column or tower
2. Is the tail shaft turning when you try to move the vehicle
3. Does the vehicle try to move at all
4. Is there any noise from the gearbox or clutch area
5. Are you certain the clutch kit was the right one
6. Did you try the clutch plate on the gearbox input shaft spline
7. Is the release bearing clear of the pressure plate fingers.
8. Does the release bearing carrier slide freely on the retainer on the front of the bearbox, and did you apply lubricant here.

ahub mens u turn L R ok u take appart to much rust or stak open chek clen grese