What is causing this?

i have an 90 oldsmobile 88 when i have it parked it makes a crackling noise and when i put it in any drive or reverse the sound gets worse, when i step on the gas the sound disappears. I would rather buy a new car than spend money at a mechanic just to find out my car isn't salvageable. Does anyone know what this could be so i can research deeper to see if fixing this is worth the money.