Had the same issue. Mine was solved by a new thermostat, new radiator cap, and the dealer burping the hell out of her. I think they spent 1.5 hours getting all the air out...

 

Love to hear if you got this figured out. My '06 G35 started doing the same thing. I just replaced the thermostat myself this afternoon, and I'm currently trying to get the darn air out of the system (yuck). Doing this "shade tree" style is a real challenge, let me tell you..

The few mechanics I've talked to have all mentioned the same potential problem - blown head gasket. I'm deathly afraid of that happening. I've not tested yet - but supposedly, you can run the car for a few minutes, then pull a spark plug and see if there's moisture on it to tell if it's a head gasket issue. That'll be my next test..

My fear, is with this nice aluminum head, it's going to warp all to hell on me if it keeps overheating...

 

With the G35 , I usually raise the front of the car as high as possible. The radiator being so low in the system is the reason people are having these issues. Even with the front raised it is still difficult to get all the air out.
I also have one of these which helps a little bit to get the air out.

It still seems to take a bit of revving to circulate the air out even lifting and using that funnel.

The recommended way to do it is to pull a vacuum on the system with a coolant flush machine so all the air is out and only coolant drawn in. Assuming you have a no leaks, a function thermostat, and cooling fan you should not have any problems after that.

 

I had the same problem, even with the water sound when driving off. I fixed it completely by adding coolant at the bleeder valve location until it's full since thats the highest part of the system. Once the car has been warmed up, take a screw driver and slowly unscrew the bleeder valve until you hear all the air go out.