my car starts up and idles rough. i can hear almost a clicking. when it starts to warm up it begins blowing white smoke from the tailpipe. it never really warms up though. the heater blows lukewarm air. i just replaced the thermostat, so is it possible that i did it wrong? i saw some of that oil/coolant mix going into my heater core tube, but i thought that i would have got that out with the coolant flush that i did after the thermostat was installed. is there a way to install the thermostat wrong so it stays open? is it possible to just have buildup in the heater core? if so, to flush it, do you have to pump water directly in there? why would the car only begin to burn coolant after it starts warming up? does that mean theres a crack in the upper part of the head?