Hi all

A crackling noise comes off from under the hood right after I start the car and I press the gas padel. If I don't press the gas the noise still comes but only sometimes.
This all happens only for a few minutes after the car is started and once the car is hot the noise goes away no matter how hard I push the gas. I tried to find out where the noise comes from and I suspect it's the radiator. My car is old (civic 99) and I don't want to spend money on it if there's nothing serious. Is this something problematic?

Thanks