[fliprayzin240sx]

If the bottom radiator doesnt get hot after a while, that means the thermostat isnt opening to let the coolant circulate thru from the radiator. No cooler coolant flowing into the engine = overheat. Like I said, you can get a thermo from Napa since they get their stuff from OEM suppliers. Just test them just to make sure before you slap it in the car. Get some boiling water, stick the thermo in there, use some kind of thermometer to test the water temp and see if the thermo opens up when its supposed to (roughly 74-80 degree depending on the thermostat rating).