dont

its in a junkyard for a reason

buy a new one

they should pressure test it 4 you .

If it's at a place where they take them out in advance, they usually test them for leaks before selling them. Ask the junkyard if they check them. If it's a place where you pull it out yourself, then it's hard to be sure.

Check at a Radiator Repair shop too. They can be a lot cheaper than buying a new one, depending on where the leak is. They can replace the plastic tank, if it's leaking there. Check in the Yellow Pages, under Radiator Repair.

Figure in the time and cost of driving too. Where I live, all the junkyards are way out in the boondocks. And with the cost of gas…

there used to places that would rebuild/ repair your radiator,steel anyway. in my area theres a place called performance radiator that sells imported aftermarket radiators at prices comparable to or better in price than junkyard. shop around!

The short answer for question 2 is you cant and the answer to question one is take it to a radiator shop and have a new core put in or just have it repaired if its just a leak its a lot cheaper than a new one

Most salvage yards ive been to do a pressure check for leaks and they also have some kind of warranty. Ask about both before buying.