[nothing192]

hi guys, im a newbie here, I like it says in the title I have a 1998 318 ti, it runs great, and suddenly the thermostat keeps saying its overheating. no smoke, and it goes back down and up in seconds. it sounds like I might need a new thermostat or just overhaul the entire cooling system. all fluids have been checked and are top notch. any advice?? thank you!