let me tell you what its doing had the car about 3 weeks now.about once a week,it wants to try and run hot...and the heater stops blowing heat. last week,i changed the themostat..it was a 160 to a new 195.car ran all week long...most it has since we have had it.usually,it tries to act up every 3-4 days.Car ran with the hot hand never even getting close to half way before i go on,it has a new radiator. ok,car ran for one week,wife goes to buy groceris and comes back in and syas it is 3/4 way up..and heat stopped.i get in it...dive it..heater come son..hands goes down some.mostly stays at 3/4.i slow to stop..no heat..i go again..heat comes back. soooo,i pull it in the yard...check everything...no gurgling of water...everything feels right. check oil again..no mixing. but i do take the radiator cap off.....smell it...smells like it has gas in it.I decide to take the vent plug off one more time. As soon as i do...i hear and see it burp 4 bubbles. so,put the radiator and vent plug back on...tell the wife to give it a go...comes back in 5 minutes....temp hand is between cold and half way(perfect) and heater is working. so,my questions 1)why the gas smell? 2)why trying to overheat/no heater? would a small HG prick cause all of this.would thta make the bubbles in the water and the gas smell?