I got a radiator off of ebay that is full of tiny fracture cracks. They don't leak just filling it with water. Have not had it under heat or pressure yet. Is the any new seal products that work without gumming up the entire rad?

What parts have the "time fracture cracks"? It's impossible to tell without more information, but if it doesn't leak when filled, I'd just go ahead and run it and see what happens. Temperature and motion are the main influences. The T cooling system is not a pressurized system, so no pressure.

I menat "tiny" not "time". Can't type or spell for beans...