Saliha, it will probably be impossible to repair. Nowadays it is cheaper to replace the matrix than repair and you'll know you're getting trouble-free results.
I don't know how much it would cost to renew....it would depend on where you take it, but on most cars, they are not too easy and would therefore take a couple of hours at the least to change.
Is it actually leaking (does it smell like burnt curry) or is it just cool????
Pete, March 2006