One thing I've found is the hood hinges may be worn out and the points where the rivets go through have elongated the holes, this can cause the hood to pop up in the rear due to the spring tension on the hinge. Remove the hinge springs and close the hood if this solves your problem order a new set of hinges and call it a day. Otherwise your looking at panel alignment issues.
Good luck, let us know what happens.
this is very often the case....
now, if your hinges are ok...you can check them , look at them closely when opening /closing the hood , if they are worn ,you can see movement at the pivot points... if they are fine...you best adjust the hood by opening it, loosening those bolts attaching the hinge to the fender , just slightly...then open the hood fully, have someone hold it in full open position , or use a broom stick, then tighten the bolts back up...
and you should not have a lose nut , you can take the bolts out...I just replaced my drivers side worn out hinge...for the second time in 8 yrs...I bought repops...they are about $35 ea, GM origs are $125 or so...each....this time I bought both new again , but only drivers had worn alot...have the pass side to do eventually... hard to do yourself....need someone to hold the hood or use tie straps to clg or such...hood will flip to side after one hinge is out...
