i got a hole about 2mm in my pajero radiator a few yrs back,there is a thing in any auto shop that is like a plastery dough,it comes in a small tube and all you do is need it together and apply,its meant to be as strong as a weld.i have a tube in my car as emergency,for $15 can get you out of alot of trouble out bush.
anyways when i used it on my radiator it lasted till i got rid off the car,about 2yrs .not saying its a permenent solution but it will stop the leak until you get around to getting a new one and is something that wouldnty hurt to keep in the car.
i also used it to patch a hole in a stock alloy rim when i had them on that was caused by a rock getting caught inbetween it and the caliper