Re-spraying engine bay

It depends on the size of the runs but you can block them out until they are gone. If you have a bunch of feather edges because of this you may need to spot prime it so you don't have any swelling when you re-paint. Depending on the condition of the paint you should be able to prep and paint with no sealer. What color are you putting on it next? This will determine how you prep the existing surface.