ok i went for a drive for about 15-20mins and when i got back i squeezed the top radiator hose and it was not hard at all..so then i took off the radiator cap and nothing happen... isnt it soppose to have fluid flying out or something??is my termostat not opening?

by the way its a b18b motor

 

was the hose hot? could be tstat not opening. try just removing it completely or just get a new one, they are cheap. Could be your water pump. (hope not since its a new motor).

Try the tstat first since its obviously the cheapest/easiest.

 

drive for a good hour or so, see where your temp gauge stands if you are overheating and you still have no pressure in your radiator then its most likly your water pump, it could also be that your motor didnt get too warm, perfect coolant/water mixture is always a plus

 

was your radiator low on antifreeze, the only way there will be no pressure present in the system is if you have a leak external or internal. So if your antifreeze is low, fill it and see were its leaking.
Dan

 

its fix now my cap wasnt sealing good..thanks