i have an 90 integra rs and my radiator seems like it does not work. the top tube is hot but the lower tube is cold. what is wrong with it?

 

Could be thermostat, clogged radiator, water pump.

Does it overheat?

 

should be your thermostat...your car should be over heating then right???.....if you are having back pressure in your reservoir tank then it should be your water pump!!!!u might want to fix that cause your motor could BLOW...