what can i use to repair a hole in a plastic radiator?

You can try a jb weld type of epoxy product. Most auto parts stores or home depot will have that. Honestly, though, it probably won't be a reliable fix and you will end up having to replace the radiator. Alex

A new radiator!

it will not work,believe me!I had to show a guy not to long ago and the coolant will come right through the JB Weld. you can buy a new Radiator from Rockauto.com for less than $90.00 and that's including shipping.no tax,2-3 business days.