overheating problems with 240 sx

my 1993 nissan keeps overheating on me only when i put a thermostat in. long story shory, radiator overheated one day and cracked the radiator. I replaced with brand new one and still overheated, i replaced thermostat it still overheated, I replaced waterpump and it still overheated, so i took the thermostat out and it does not overheat, circulates just fine so i know everything is working, i checked the thermostat on stove and it started opening up at about 190 deg. and fully opened. so i put the thermostat back in and i do not see any circulation seems to be alot of backpressure though, wants to try and bubble out. didnt seem to over heat until i put the cap on, does not leak out of cap, and does not leak anywhere else, does not seem to be losing any water after it overheats. i am completely baffled, please help.

hey i had the same issue with my s14, sounds like u have air in the cooling system. This is what i had to do. Get a floor jack and jack the front of your car up as high as it will do make sure it's safe tho. pop off the radiator cap and take off the bleeder start the car and let it run with ur heat on high. this will let all the air out of the system. make sure that the coolent is toped off with fluild tho while the car is running because it's going to spit coolent out as well as air.

good luck