Nissan Repair: air in radiator, radiator fluid, rad cap

Question
I tried to "burp" trapped air from my radiator and here's what happened.  Took the rad  cap of, turned the heat on and ran the car until the cooling fans came on, coolant got sucked down into the radiator.  

Then i turned the heat off.  The coolant did not go anywhere in fact it started to spill out of the radiator.  The only time it went down is when I had the heat on in the car.  Is this normal?  Even with the heat off, shouldn't the thermostat still open and allow coolant to flow thus the level in the radiator should go down and not spill out?


Answer
George,

No, the radiator fluid will expand as it gets hot.  And, it will flow out of the radiator when it is at idle.  You can fill the catch tank and drive the car until warm and then let it sit until cold and it will suck antofreeze back into the radiator.  Do this a couple of times and the radiator should fill all the way up...  Just keep the radiator full when cold and the catch tank to the top fill line.