Leaking radiator

I recently realized that my reservoir bottle was losing coolant slowly. I started looking for leaks and realized that the radiator was dripping coolant when I start the truck, but the strange thing is that it would stop leaking once the pick-up got warm. I took it to the shop and the mechanic discovered that the core of the radiator was damaged, so he recommended that I had it changed. The mechanic surmised that what was causing the leak was not the damaged core per say, but rubber seals in the radiator that would expand once the vehicle got hot and then stop the leak. Has anyone experienced this issue before? I've changed the radiator two weeks now and I've not noticed any leak or drop in the coolant level in the reservoir so far.

 

I had this exact same problem with my T-100. I replaced the radiator and the problem went away.
It was the seals on the tanks which were crimped on the sides of the core.

 

Yep, I had this happen on another truck I owned. It leaked around the crimped seals on the tank until it warmed up.

 

Cool. It's not one of the first places that I thought about, to be honest. So it took sometime to figure out.

 

Yeah, mine threw me off for a while because it started showing a drip or two on the ground only on the mornings when it was really cold, like in the single digits. Then, about six months later, I got out of my truck one warm day and smelled coolant. Popped the hood and it was getting more obvious.
A radiator replacement is a fairly straight forward job. Just DON'T get any coolant on your belts. They'll squeak until you replace them.