Dewalt 18 volt cordless drill the chuck is stuck in the fully open position and wont close

Try beating on the side of the chuck with a rubber mallet and then try and close.

I would make sure that the bit is firmly installed in the chuck, you should hear clicking when the bit is tightening, this is the chuck locking itself on the but. and when going in reverse make sure you dont have your hand or have the chuck pressed against an object. If nether of these are the problem then there may be a problem with the chuck itself and should be replaced.

Just took apart a DeWalt, the chuck has a left hand scew that holds chuck in place, may be the problem

Use a pipe wrench to turn the chuck open. J.

Do the same in reverse, if possible. Also, you could use two channel locks as most of those chucks have two rings, the narrow one towards the drill itself being attached to the motor. However, make sure the screw inside the chuck is tight first -- I've seen those back out and block chucks open.

WD-40 works well on most power tools for freeing up stuck parts without damaging the drill. It's also good for displacing any water that may have gotten in it.

if chuck is wide open ,look down inside there should be an allen screw or bolt at the bottom of the chuck it should undo anti clocwise and the chuck comes off

if the chuck is rusted start with some WD-40 on the chuck body. Then what I would do is take a rag and wrap around the chuck collar and using a pair of channel locks grip the collar with enough pressure to hold but not break it and using the tool in the low position pull the trigger switch SLOWLY and see if that doesn't free up the chuck. Let me know if still stuck and I will come up with something else, but this usually works for me.

there is a recall on them I believe.

ya its a chuck problem wont hold in reverse