hello, i was wondering if u guy could help me figure out my problem on my car. I have a 1st gen b16a. I have changed the water pump, thermostats, and flushed the radiator a couple of times and it still overheat. but the weird thing that is overheat only on the freeway.I could drive it for a good 15-20min before it overheat.When i take the inside road my car drive fine. When it overheat i have to turn on the heater to help it cool down. My dad rewire my radiator fans to the battery and make a switch for me to turn it on and off whenever i want. I been driving like this for 2 years now and im tire of it. please help me...... hopefully it is not my head gasket.

 

does it overheat with the fan on? could be a thermal fan switch? Next guess is head gasket, but you would be smoking white smoke and eatin rad fluid.

 

yes it still overheat with the fan on, but it's doe not smoke at all