Hello I have a 01 cherokee 4.0 strait six. I recently noticed that it was leaking coolant slowly when i shut off the engine from the inline under the radiator cap (not leaking from cap) do I need a new radiator

 

Is it leaking from the little rubber line just under the cap? If so the line may need a small hose clamp. Even if that is whats leaking, coolant pressure should not be there unless the system is over pressurized or the cap is bad. If coolant is leaking below that, you need a radiator.