: Is my STS overheating?

07-23-12, 09:52 PM
Hi folks,
New here - just purchased a 2008 STS4 with V8 Northstar a few months ago. I LOVE this car.

The other day while arriving home from work I stopped in the street to talk to my neighbor for about 15-20 minutes. It was pretty hot out (about 95) and the air was on while my window was down. After about 15 minutes we heard a noise under the hood - it was coolant shooting into my overflow tank. Is this normal??? I haven't had a production car overheat on me in a long time. MY temp gauge almost always reads just under halfway - which seems a bit higher than I'm used to seeing in other cars.

I phoned my dealership today and the service dept guy told me Northstars do run warm and there's nothing to worry about. He also said that just under half way up on the temp gauge is normal. I didn't really feel like I got a solid answer on the coolant shooting into the overflow tank though - so I thought I'd ask what you all see.

Has anyone else with a Northstar noticed coolant shooting into the overflow tank like this?
Where do your temp gauges show the needle at operating temp?

Thanks in advance!

07-23-12, 10:18 PM
Read my post called "a little hotter than normal"...I only have a 3.6 but my problem may have been the same reason yours had the coolant thing going on

07-24-12, 10:16 PM
Thanks DMBSTS. I'll check the fans next time I'm out. Sounds like that would be a nice simple fix!

Anyone else out there ever seen coolant streaming back into their overflow tank?

Also - I forgot to mention that my STS has the V03 Performance Cooling Package. Is this just a larger radiator?

07-24-12, 11:17 PM
go get your cap checked? if it doesent seal properly it will cause the resovoir to overfill

07-25-12, 12:14 AM
Being that it was hot and the car was idling. I don't think it would be something to worry about. Thats what the over flow tank is for. You might not have ever noticed it if you were sitting in the car. While a car is idling and not moving is when engine temp will be the hottest and just under half mark on the temp gage is not overheating.

07-25-12, 07:44 AM
The resevoir tank is for expansion and reserve. When the coolant is hot it expands. When the engine coolant cools down, the coolant is drawn back into the radiator as the fluid contracts. You never want an empty resevoir because that just introduces air into the system. Half way on your coolant gauge is normal operating temperature. If its not above that your fine, also if i remember correctly there is a cold and hot mark on your resevoir. With your A/C on, your fans should be cycling on and off also. If they werent working correctly your car would tell you.

07-25-12, 07:52 AM
If you dont have coolant on the ground, your not overheating, and your coolant level is correct, your cap is fine. Next time its all warmed up just check where the fluid is compared to the Hot mark on your coolant resevoir. But from what your trying to explain, sounds to me like a normal cooling system operating correctly.

07-26-12, 10:36 PM
Thanks guys - I'm going to call this issue 'solved'. It's great to be able to ask the opinions of a bunch of knowledgeable caddy owners!

07-27-12, 10:45 AM
That's why I love this forum! To receive and give knowledge!