JB it with clean prep and no coolant for at least 24 hours and don't do it outside with temps below 60
Paul is correct. I have repaired radiators both ways (solder & epoxy) and both work.
1. all epoxies will chemically resist antifreeze.
2. all epoxies will be OK with roughly 300F continuous temperature.
3. Slow cure epoxies are stronger, stick better & have better chemical resistance than 5-min. epoxies.
4. all epoxies stick very well to all metals that have proper SURFACE PREPARATION as another poster mentioned... including lead. For plastic, you need a 5-min.type epoxy designed for plastic (mercaptan based pt. B)