Thread: 2004 3.8 Cooling system problem

Ok I can only give vague descriptions as to whats going on since its my girlfriends car and shes horrible with describing the problems. So......her car just blew a head gasket due to overheating, so instead of paying to replace the head gasket she bought a used 50,000 mile engine. So what it does is warms up to running temp, and then it creeps over center by "two notches" and then it goes back down. Most of the time it happens is sitting in traffic, and she says that it runs pretty much right in the middle when shes driving. Now that being said, she just had some things checked out at the dealership. They said the fan is working properly, the thermostat may be sticking but it didnt look like it. Also keep in mind that these problems existed with the old motor and now the new(used) one. The place that did the swap said they didnt take anything off her first motor so I would assume that they left all the sensors and what not attached and she now has the "new" sensors. So what are the odds that the old and new coolant temp sensors are doing the exact same thing. In the old motor she had the thermostat changed numerous times and the water pump. The problem never went away. So whatever the problem is its still there somewhere. She is about to have her radiator changed since a shop told her it may be plugged with corrosion a little. And her old motor had 27X,XXX miles on it also. So any ideas of the problem would be greatly appreciated, I am so f'n tired of hearing about it. So pleeeeease help me!!!!!!!!!!!!!!!!!!!

Is that just a grand prix thing, cause I've owned a bunch of cars and trucks and done a bunch of racing and never had this happen with any of them. If they ever go over the middle then it was on the initial warm up and then they would get right back in the middle and then never move again. All my vehicles have been the same, it heats up to the middle(which the middle line indicates the optimum running temp) and the vehicle maintains that temperature. And every time I changed thermostats to a lower temp one, my vehicle would maintain that temp. It never mattered if it was cold or hot as $hit out, they always were able to maintain the right temp. So I assume there has got to be a small problem somewhere.

And on the old motor she had the fluid changed and the shop bled all the air, and also her uncle thought the same thing so he tried bleeding air and got nothing. The problem never went away no matter what they did.

Mine creeps up and down while driving - unusual for most vehicle I have driven, but seems "normal" for this one. If I am pulling the "pig trail", the temp creeps up quite a bit (it's full of hard pulls, curves and slow Texans that have never seen hard pulls and curves ). But, when the road straightens out and flattens out where I can cruze at a set speed in OD, the temp goes right back down. I am attributing it to the combo of slow speeds and transmission fluid heating the radiator in the heat exchanger. However, this is the first 3.8 I have owned (less than a month) and I do not yet know what is "normal" for this vehicle. Of course, shifting out of OD (as you are supposed to do in the hills) does help. And, it is nothing like the temp changes in my 78 F150 400cid in stop & go traffic. I can almost keep cool from the temp needle waiving back & forth. It will soon get an electric pump and fan to keep the water and air flow more constant regardless of engine or road speed.

Just be glad that you have a GF/DW that actually notices the gauges .