ok i had to take off my altanater so i can remove my valve cover so when i was puting it back on i droped the screw u put in the back of it its like 1 1/2 inc long do i need it because i dont think my battery is charging plz help

o yea its a 1995 caprice lt1 if u need to kno

if by screw you mean a nut than you you need that. i don't think there are any screws that go into the alternator. But as long as the power wire from the alt goes to the battery it should charge. if your wire is loose and not connected than its not going to work.

if you dropped a mounting bolt it'll still charge but the alternator will bounce around and the belt will slip and it wont do anything. and possibly destroy the alternator from intense vibration.

a general rule of thumb anything that you take off you usually need to put back on.