hey guys sorry to ask a 180sx question but it's the same thing, and the guys on nissansilvia arnt so trust worthy in their answers sometimes

my 180sx doesnt overheat regularily (driving around town) but on the rare occasions i go somewhere down a freeway or out bush and sit above 90 km/h it starts over heating, the faster the worse it gets

the best way to cool it has been to actually stop the car and let it idle, or reduce speed below 90 for a while and the temperature will drop

it will overheat when cruising or driving hard above 90km/h

i removed my numberplate as it was blocking some airflow... no change

i put the heater on full and this seemed to keep it at a normal running temprature, though turning it off it started over heating again

seems odd... just finished checking the thermostat, at $50 for a new one i decided to just test mine, raher than replace anyway

i put it in a cup and poured in water from the kettle, and it slowly opened up. seems to be working fine

any suggestions on what the cause might be, i haven't come accros this problem before