ka overheating??

[SLEEPERracer]

did a search on how to bleed the cooling system, but havnt tried it yet. but my car doesnt overheat all the time. i could go a couple weeks sometimes months before it happens again. i mean it never really gets passed the last line before H, but just in case i blast the heater or pull over till it goes down, from there i check if i have coolant. sometimes i have to refill it but not a lot. after, everythings back to normal and it doesnt overheat anymore. so far ive only notice it happen wen im in traffic or at night. i see no leaks or anything. im running an aluminum radiator. i was thining about changing my radiator cap but not sure if i should change my waterpump and thermostat as well. the previous owner sed the waterpump and thermostat was replaced but dont kno wen. any help thanks!