2000 Saturn SL2 Overheating.

Hello,

I was driving in rush hour traffic (really slow) and noticed my temp got high, and smoke began to come out from under the hood. I pulled over immediately, waited for it to cool, and added some rad fluid, and went on my way.

Everything seemed fine for a few days, but, I got stuck in traffic again, saw the gage go up, smoke, pull out of traffic for cool-down again.

There are no leaks on the ground, I don't see any bad hoses.

Any ideas on what it could be, compression prob, air pocket in rad?

I want to give this car to my son (his first), and just want to get it up to standard for him. Everything else in the car works great, it's been well maintained.

Thanks for any help.

Mike