boiling sound comming from under the hood

[auto180sx]

today, i went to go do a few things, just cruising, happy that it was such a nice, cool day and i was in my 240. but i noticed that when i got home, there was a boiling sound comming from the radiator, i think any ways. i was hungry, and i had my lunch in hand so i went in and ate. i came back out, checked every thing, coolent, oil, so on and so froth, and everything seamed to be ok, :help

[drjohn]

Check the radiator cap, it may not be holding proper pressure and allowing the rad. to boil over into the rad. overflow bottle.