Pontiac Repair: 2004 Grand Prix temperature gauge, coolant temperature sensor, electric cooling fans

Question
Hi. I am wondering where the needle on the temperature gauge in the average 2004 Pontiac Grand Prix 3.8L V6 should be. My '99 (series 2 3.8L) stayed like clockwork between 1/4 and 1/2, on highway or in city traffic. This '04 regularily goes betwen 1/2 to 3/4 when in stop and go traffic and stays just under 1/2 on the highway. I have changed the water pump, thermostat, coolant temperature sensor, and flushed the radiator as precautionary stuff already. Is this a  normal operating temperature for the series 3 3.8L? Any info you can provide would be appreciated.

Thanks,

Answer
Hi Brent:

the cooloing systems on modern cars are different then older ones. depending on the application the cars had 1 or 2 electric cooling fans and some of the fans are 2 speed. the thermostats on the cars are usually 195 degrees F. the electric cooling fan(S) typically will not come on till around 220-225 and then as high as 234-240 before the Hi speed or the second fan turns on. So there is almost a 50 degree swicn between the thermostat opens and what is the hottest the engine will run which would give you the swing in the gauge. a few things to look at are #1 make sure the air dam is still in tact under the radiator and I have seen in certain areas of the climate if you have the cotton wood trees where the space ebetween the radiator and the a/c condenser get pack with the cotton wood pollen and then the diryt sticks to the cotton wood and plugs up the air fins in the condenser and the radiator. Usually washing it down with a garden hose nozzel will clean it out. So to answer your question the temp is more then likely normal and I explained the temp cycles. I wouyld let it sit and rin with the hood closed and the a/c on just make sure that both cooling fans work if equipped.. Good luck :-}