Overheating?

Had to replace my radiator cost me $143.00

Hello -

My water pump failed in February and I had it replaced. I also had my transmission rebuilt in May (torque converter). Prior to having the transmission revuilt, the transmission fluid temp was consistently running high (200+ degrees). Almost immediately after having the transmission rebuilt, I was out of the country and my wife drove the car while I was gone.

After returning, I noticed that my engine temperature would run hot fairly quickly (consistently into the last hash mark prior to getting into the red). It only cools when travelling at high speed when ambient temperature is cool. Subsequently, the transmission fluid is also hot (again, 200+ degrees).

I'm not sure whether there is an issue with the water pump that was replaced, or could a thermostat with the wrong setpoint have been installed? The car is still under warranty (barely) and would like to have a better guess as to what the problem may be. If there are any procedure checks I can do to narrow it down as well, I'd be more than happy to try.

Thanks for your help!

Thanks for the response - cooling fans are not kicking on, engine temp just ramps up.

Two days ago a squirrel tore into the wiring loom directly off of the fuse box near the firewall(passenger side). I spliced all wires back together, however am still seeing an overheating issue. Both 30amp fuses marked "Fan" in the under-hood fuse panel are good. Not 100% sure on the two fan relays in same fuse panel, HOWEVER, the radiator fan's DO work when the interior AC or heat are turned on. Also, the temp gauge in dash works, and shows a steady rise in temp, so I'm assuming from that that the temp sending unit is reporting actual temp to the ECU. Is there possibly a secondary temp sending unit elsewhere that triggers the radiator fans to turn on?

I've replaced the water pump, coolant temp. Sensor, thermostat, flushed the radiator, will radiator with 50/50 coolant to water. Still over heats. No noises or leaks. Gauge goes to hot within 2 miles or approx 10 minutes of running. A/C shuts off and car has turned off due to over heating. What could be the solution? I'm trying to prevent the costly trip to the dealership.

Thanks for the options. I've actually fixed the problem. The thermostat that I replaced about a month ago, was defective. The thermostat would not open when 195 degrees was reached. Auto Zone is going to issue me a refund for this. I purchased a ACDelco from the local dealership and it works great.
It was suggested by a salesman at an auto parts to run the motor without the thermostat to verify that the thermostat was working or not. After I removed the thermostat, the engine ran lower than normal temps. Thank God that this problem is now resolved.

Hello, I have a 2006 grand prix gxp. I heard alot about them having the transmissions overheating. Alot of people said the problem can be fixed by a transmission cooler fan. By any chance does the car come stock with this?

I started it up and within 5 min the temp started to go up quickly. During this time the fans did not kick on and after shutting it off I noticed some coolant leaking at the top of the block

My 2006 Pontiac grand prix was starting to overheat so I went and filled it with 50/50 Coolant/Antifreeze. After doing so I got about 10 mins down the road before the temperature rose incredibly fast and was as hot as possible. I got a hot coolant alert and another saying the AC was disabled. I stopped and after waiting 30 mins put 2 Liters of cold water in the coolant tank while running the engine with the heat on. A steady stream of what looked like coolant and water started coming from under the car on the side with the coolant tank. I was able to get home but within 10 mins the engine temp was back up on the edge of the red. After 20 mins of being home there is a small puddle of green/clear liquid that seems to be leaking from under the coolant tank. What advise would you give in proceeding from here?

Hi, it's a 3.8L V6 engine and has just over 104000 miles. The coolant was last changed around 2 years ago. The puddle is forming right where you said it was, to the left of the right front tire.

My car over heats while driving slow and climbing hills, it also over heats going hwy speed with A/C on and climbing hills on a hot day. Going hwy speed on level ground it does not. Thermostat? Or radiator? Or something else. Cooling fans are working. Also I heard the orange anti-freeze (dex cool) causes problems, is that true? And should I switch? One more question. My key is stuck in my ignition, shifting to park will not disengage it. Any simple solutions to this problem?

Thanks

Dave