Car overheating! confused

[bandunga64]

I have an 89 240sx. The problem is when the car is idleing it will overheat. If i'm not at a very high rpm it will over heat as well. However, if i rev up the engine to about 4or 5k the temperature sensor's reading will gown down. Once the car begins to overheat i park it immediately. When i pop the hood I can hear the coolant bubbling in the overflow tank as well as the radiator. Also, if i park the car and then try to start it within an hour or two it is very hard to start, I have to give it alot of gas to get it to start. And it will blow smoke out the back. Ohh and another symptom is when the car begins to overheat it backfires really bad. I'm not really sure what to do here guys. Any advice is appreciated.

[912.0turbo]

Thermostat,waterpump,air in the cooling system,radiator?I would check the radiator for leaks first then move on to the air in the cooling sytem then narrow it down from there.

[MikeMurphy]

bump.

I second the air.

[CanadianCoch]

email me for my overheating FAQ, will solve your problem.Betting air in the system

Dr.