You're supposed to put a new spring clip on the end of the axle every time you pop it out. No one ever does. But those clips must sometimes go bad eventually. That is if there even is a spring clip on there.

If it "popped out and got hung up" it's likely that things are pretty torn up now.

 

we changed the passenger side axle it wasnt lookin to good after it popped out on the interstate..it actually locked in this time so he drove it for the first time today since he changed it. it seemed to do ok (but last time it seemed ok on his way to work. and it was on his way home that it popped on the interstate.). he called and said it seems fine but now he hears a grinding sound . like metal rubbing on metal. any ideas what that could be. maybe something where the axle meets the hub .. all i could think is maybe that guard behind the hub may be rubbing? i dunno.

 

Without being there, all I can do is be Capt. Obvious and state that 'grinding noises in the driveline (especially after having just worked on it) are never good.'

Good luck.