Hello everyone. I have been researching about my heat issues and have not gotten much help. I have an 03 Murano that recently started sounding like water would rush under the passenger side floor board when I would take off from a stop and the heat would get cold when I was at idle for a period of time. I searched and found that I probably had an air pocket in the system. I burped the system and all was perfect for a few weeks. Then I noticed the sound again and the loss of heat. I went thru the motions of burping the system again and all was fine for a few days and now I have air in the system again. I noticed that my overflow tank was filling up after each time I had this issue. I replaced the radiator cap and burped the system again. A few days later I have air in the system again... I do not have the typical blown head gasket issues. No coolant in the oil, exhaust is not steaming any more than normal in cold weather, only adding coolant to the radiator because its being pushed into the overflow tank which creates an air pocket at the heater core so when the car cools down it doesnt have room for the overflow tank to return the coolant due to the radiator appearing full. Can anyone give me suggestions??? I am at a total loss on this one. Never had issues like this with any other car I have ever owned.