93 blazer that runs at normal temp all of the time and seems fine but when you take it for a 20 minute drive and then shut it off the antifreeze comes back out the overflow reservoir. not all of it but some of it. the longer you drive the more comes out. but driving it or just leaving it running it is fine
anyone have any ideas?

 

Sounds like the temperature is increasing after you shut the truck off and is pushing coolant out into the overflow bottle. It shouldn't come out of the overflow bottle unless the bottle is too full...

 

when it is running it is at the hot mark on the reservoir. i was toldtaht there could be air bubbles in the system. anyone know how to get them out?