Radiator cap leak

[01saharatj]

My 2001 Jeep Wrangler leaks from underneath the radiator cap. It’s an aftermarket all aluminum radiator from about 6 years ago. Recently started having issues of fluid leaking from under the cap. I’ve replaced cap (OME) with one from parts store…. When I bought radiator it came with radiator cap, do I need a higher pressure cap? Stumped. Any help appreciated….

 

[Gilaguy23]

The neck could be cracked, tanks are just plastic , the top of the neck where the cap seal sits may be distorted (chevy problem of past) the overflow hose nipple could be cracked or leaking also if the hose is to loose. Those are some of the things I can think. You should also eventually get a coolant crust around the source so you can tell exactly where its leaking from.

 

[CharlesHS]

The neck could be cracked, tanks are just plastic , the top of the neck where the cap seal sits may be distorted (chevy problem of past) the overflow hose nipple could be cracked or leaking also if the hose is to loose. Those are some of the things I can think. You should also eventually get a coolant crust around the source so you can tell exactly where its leaking from.

The OP said the radiator is ALL Aluminum, but the problem could still be a cracked neck since they are probably welded or the nipple sealant may have started leaking.
I would thoroughly clean the surrounding surface areas of the neck and nipple; ensure the mating surface of where the cap gasket seats is not pitting or cracked.