rad could be blocked.


also possible damage if geniuinely overheated:

if your expansion tank is bubbling away (with cap on) take it to a garage and have a sniffer test done. if it picks up hydrocarbons then your head gasket is fucked and the head probably warped too!!

is the oil ok? no milky, creamy residue on the dipstick or filler cap? this would also indicate head gasket failure.