93' 240sx overheating problem

[Burukan]

been searching everywhere and still have no remedy. my car which is a 93 240sx hatch with about 186k on it has been getting hot for some time now. i havent been able to diagnose the problem so i was using the remedy of driving with the heater on which seemed to be working fine until a few days ago. for some reason my heater started to blow cold air. i thought it was odd and when i shut it off, i could smell the heat of the engine. i was about to pull over to the side as i was approaching the toll and the car shut off on me do to overheating, temp gauge must be messed up cuz it was still in the middle. after sitting there for about 1/2 hr i filled the rad and reservoir and took it home. there i changed the thermostat, water pump, belts, as well as flushed out the heater core and burped it thru the coolant hole. what ends up happening now is, when i drive, within a minute or two the temp needle will rise to H, heater blows hot air sometimes mostly cold so doesnt really help in lowering the temp. when i pop the hood, the overflow tank is boiling and shooting off steam. (steam actually that you can see while driving. yet the valve cover isnt too hot. radiator is relatively new so i didnt think there would be a blockage there. i thought maybe there was still air in the system, so i idled a bit with the rad cap open and although it was filled with water, nothing bubbled, even when i shook the car. only white smoke/steam came out. i keep getting told it could be a blown head gasket. however the symptons of which i was told are not present. (that i know of). no white smoke out the tail, no mixture of water and oil. so i was thinking it could either be the head gasket or possibly the heater core im not sure. Any input ?

[elwesso]

welcome to NICO.. unfortunately i do think its a headgasket, i saw the exact same symptoms on a cadillac..... no smoke, no oil mixture, only blew coolant out of the overflow... what can happen is youll blow just the portion of the gasket between the cylinder and the coolant jacket, which causes the coolant to be under a lot of pressure only when the engine is running.....

its very possible the car is not overheating but it is blowing coolant out.....

[Burukan]

well if thats the case it would be good that i now have a culprit, but now the symptoms are worse. i tried to flush the rad thinking possibly that it might have been clogged. i flushed it and then after refilling it, my car started to stall and turn off while reversing and during turns. pretty much when my foot was off the gas. i left it alone for the night because i didnt have any idea what it could be. i tried it today and it wouldnt even crank. it tried to turn over and then just died. any input on that ?
Modified by Burukan at 6:56 PM 1/14/2007