My 02 Maxima has radiator fluid across the top of the radiator where it appears the plastic cap is fastened to the aluminum body (or so it seems). There is radiator fluid all the across the top of the radiator long this plastic/aluminum connection but more where the heater hose connects (first pic) and it appears fluid ran down the plastic fan housing. The hose is new 1 year ago and I don't see any signs of it leaking, just some splatter on the side of the hose most likely blown there from air coming into the front of the car.

Does anyone know if there is a seal between the plastic cap and the aluminum or do I just need to replace the entire radiator?

 

Time for a new radiator.

 

The radiators are known to do that. Replace it with a TYC from Amazon or RockAuto and call it a day.

 

Thanks User1 and TallTom, I appreciate it.

 

This happened to me too recently. If you haven't replaced the radiator yet and you need to buy some time until you can replace it, here's an idea.

Go to an auto parts store like Autozone and borrow their coolant system pressure tester. Connect it to your radiator and pressurize the system. You'll see air and coolant escaping where the leak actually is. I doubt the leak is actually where the plastic meets aluminum, that is just where the coolant is collecting, but you won't know until you test it.

If the leak is up higher on the plastic you can plastic weld it.

The plastic on the radiator is nylon. I got some nylon zip ties (must be nylon) and used a flat tip on my soldering iron and welded the whole area. If you don't have a soldering iron or a big flat tip for it, you can get the Harbor Freight plastic welding kit for about $20. I thought the repair would only last a week or so because the crack was huge, but it ended up lasting over 2 months until I changed the radiator. After replacing the radiator I took the old one apart and looked inside. I bet the repair would have held up indefinitely.