My temp gauge says my engine is running on the hot side. It spiked yesterday after 5 minutes of driving and I pulled over. I tried to turn on my defrost all the way to HOT, full blast,but no hot air was coming out. I idled my car and the gauge stayed in the middle. This morning, after 10 minutes of driving it spiked for a few seconds then stayed at 3/4 hot. I checked the coolant level, it is fine. Could it be my thermostat? Where is it located?

 

If the car was cold when you started, 5 minutes of driving would probably not be long enough to overheat it. When you say the guage spiked, do you mean it jumped suddenly from a normal reading to the HOT redline? If it did, you probably have an electrical problem and not a temp or thermostat problem. With no hot air from the defroster, I'd guess it's electrical.


Post whichyear and engine do you have, since the thermostats are in different places on each one.

 

The gauge was 3/4 of the way up. Then it just went to the red zone.I went ahead and added some anti-freeze and it seems fine today. But my stupid coolant light is on. Someone suggested a leaky hose, I cannot see anything wet underneath the hood and I don't have a puddle under my car either. Could I have a leak in my lower intake manifold? I remember a lawsuit againt GM because of the Dex-Cool making a sludge in the manifold, Maybe this is the problem?


I have a 99 V6 3.4 engine

 

How low was your coolant level before you added some? How much did you add?


Coolant doesn't always leak outside the engine. My brothers Olds leaked past the head gasket into the cylinders for a while.


Dex-Cool does have a bad reputation for sludging if there is air in the system. If your coolant level was below the cold mark on the tank, you might want to bleed the system to remove any trapped air. Any shop can do this pretty easily. You might want to get a radiator flush and switch to green coolant at the same time to eliminate any future sludging problems. I've heard about the lawsuit also, but as far as I know, GM blamed low coolant levels for allowing air in the system, therefore it wasn't their fault. Does anyone have any more info on that?


I would look at the coolant temp sensor for corrosion on the connection, or worn wiring before anything else. It is located under the throttle body. Follow the upper drivers side radiator hose to the engine block. Just left of where the hose attaches, you will see an electrical connection with 2 wires coming out and going towards the rear of the car. Unplug it and see if you have any corrosion inside. If so, clean it with some electrical contact cleaner, let it dry, and reinstall it. Look at the wires for damage also.