How do you tell if you need a new radiator?

Answer 1

Three main reasons for replacing a radiator are 1) it leaks and replacing the radiator cap, hoses/clamps and making sure the drain valve at the bottom is complely shut hasn't stopped the leaks, 2) lots of rust on the lower half, especially on the cooling fins and at weld points where hoses connect, or 3) a radiator flush machine at your oil change shop shows that the flow through it is badly restricted due to mineral and rust buildup and the flush didn't improve it dramatically. Before you replace it, do replace the radiator cap. Sounds silly, but a weak spring or badly worn gasket can give symptoms that look exactly like a radiator about to die from not being able to hold pressure correctly. Inexpensive cap vs radiator? Easy choice. If you end up replacing the radiator, you'll need the new cap anyway.