Temperature runs hot when in traffic, cool at speed.

Asked by Jun 27, 2016 at 10:58 AM about the 2003 Pontiac Grand Prix GT

Question type: Maintenance & Repair

I just bought a 2003 Pontiac Grand Prix GT with 184k on it. After my initial drive home, I noticed a large puddle under the drivers side of the front bumper. I tasted it, and it had the sweet taste of antifreeze. There is still coolant in the reservoir. I drove it to work today (32 miles of freeway), and it ran cold, until I hit traffic, when it rose from 190ish to 225ish degrees. Then went back down when I got moving again. When I got to work, I didn't see a puddle, so I'm wondering if that was just excess coolant being expelled. Also wondering if it's normal for the 3800 Series II to fluctuate like that. Thanks!

4 Answers

100,345

Check the cooling fans operation, 225 is getting just too close to boilover and engine damage. You will notice some gauge movement like that once during the warming up cycle and then again in stop and go traffic, but just in cruse the gauge should remain stable at or around 195 to 200 degrees. The puddle is of some concern as there are only a few things that can leak that far out front even if it hit the lower core support and ran across to the drivers side. I would be checking the hoses and the radiator for signs of leakage.

Okay, so in traffic it's fairly normal? Because that is when it happens. At cruising speed (80MPH or so) the engine stays very cool. I'm taking it back to the dealer tomorrow morning to see if there's any leaks in the radiator or hoses, but I was just hoping it was spewing the excess or something. Still no signs of a puddle today, and there's still coolant in the reservoir.

100,345

In traffic yes the gauge swing is normal, just make sure the fans work as 225 is cutting it close, of course it could be a gauge reading slightly hotter than it really is, the shop should be able to plug in the the system and read what the sensors are really seeing.

Alright, good to know. I appreciate your help, man.

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