Radiator Leak on top Plastic Tank

[Microman]

Daughter in Laws car got towed home today.

Checked oil, checked water. Later in the day, started it up, and I see a hairline crack in the top tank. I removed the radiator, and have it sitting in the back yard.

I can't remember, ...... when I have taken radiators to be repaired before... is it when those plastic tanks are cracked that the whole radiator is shot? I have a radiator place, but they are closed till a.m.

Thanks.