Hey Rufrob - How is your radiator repair holding up ? Hopefully it will be long term. The JB Weld epoxy you used should seal a cracked aluminum radiator OK as long as the damaged surface was pre-cleaned really well with alcohol and a toothbrush.
Years ago I made a Texas Speedway track side repair on a 930 water-cooled intercooler using JB Weld + a small square piece of aluminum. A missed turn punched a dime size hole that was patched long enough to finish the days events.
Good Luck Michael
