I bought a thermostat for a 92 240sx 9 months ago. Because of the leak I have with my car water pump, and pipe from manifold. I started using just water in the radiator. 8 months later I fixed the water pump and the pipe. For about a month my car was running fine without overheating. Now my car is overheating again and it is worst than before. I put antifreeze in there now. I bled the cooling system and its still the same. Could the thermostat go bad again? When I turn my heater on sometimes when its running fine the heat comes on but when its hot no heat comes in the blower. thanks for the help