i have an 04 350z enthusiast 6 speed and i bought the car back in april when it was still warm but when it started to cool down i had a cel come on saying thermostat failure or ect sensor failure. i bought the thermostat and when i took the old housing off to replace the thermostat i found that my car had no thermostat in it. i put the new thermostat in and reset the ecu. i turned the car on and within about three minutes it was up to operating temperature and acting just fine. i let the car idle about another 10 minutes while i checked on something in the house and when i came back out the car was starting to over heat. i took it for a spin around the block to see if maybe some air flow would cool it down, and by the time i got it back to my garage it the temp needle was all the way up. i tried to turn the heater on to draw some heat off the motor and it blew ice cold ac even with the temperature set at 90 degrees. i have since taken the thermostat out but i am getting very nervous driving the vehicle as it is getting colder and the vehicle will no longer get anywhere near operating temp. my heater works when the car starts to warm up but only when im giving the car some gas, if it sits at idle or the engine speed slows down, then its starts to blow colder and colder air. please if anywone has any insight it would be very appreciated im drawing up a blank and dont know what else to do other than take it to a shop so they can try to fix it by trial and error and waste all of my money that i have little of at the moment.

 

You need to bleed the coolant system, simple, but a PITA

 

As mentioned, make sure the air is bled out of the coolant. Also, you might want to test your thermostat in a pot of hot water w/ a thermometer to make sure it is fully opening at the correct temperature. If it was not overheating before and you did nothing more than add a thermostat, it has to either be air in the coolant or a faulty/incorrectly installed thermostat.

 

ya i tested the thermostat and it starts opening around 160 and is fully open around 185ish. ive never really bled a coolant system before. if nobody minds explaining it it would be much appreciated. ill try a search right quick too so i cant be blasted for not using the all knowing search function lol.