Let your engine gets to operating temp or hot. Then shut off the engine and go under the hood and feel your radiator in several spots. It should be the same temp or feel the same all over. If you feel cold spots or see fins that are loose or corroded, then your radiator is probably bad. Also if that doesn't do anynthing have a pro put apressure tester on it to see if there are any leaks.

Answered by hmac300 (expert)
17,905 answers provided

If you are going to spend any more money, have a block test for combustion gases in the cooling system. Head gasket leaks are not uncommon.

Answered by factoryjack (expert)
4,285 answers provided