Skip the auto shop - Our mechanics make house calls

Q: My car runs hot but it never overtheats the temperature gauge moves up and down

asked by on

My car runs hot but it never overtheats but the temperature gauge moves up and down when I'm driving in the freeway is ok but once I get off or I'm at a stop light the temperature gauge strats to move move up and down

My car has 125000 miles.
My car has an automatic transmission.

A: This is could be a classic symptom of a coo...

This is could be a classic symptom of a cooling fan not operating. When your car is moving, air is passing over through the radiator allowing it to dissipate heat. When you car is at a stop, there isn’t any air flow passing through the radiator while stopped. That is where the cooling fan comes in. The symptom you describe with the temperature gauge could indicate other problems though.

If the temperature gauge is fluctuating while driving, this indicates there is a low coolant condition or the thermostat has problems. On a car with 125,000 miles, I would definitely suggest a new thermostat. But before you put one in, you should take a look at a few things first.

Check the coolant level cold. If the coolant is low, you need to find the source of the coolant leak. The 3.8l has a few common coolant leak failures.

The drive belt tensioner has coolant passages in it that feed the heater core. The pipes that come out of the tensioner are sealed with rubber o-rings.

The water pump bypass pipe is usually plastic. There are after market elbows that are metal.

Of course there are the usual suspects such as hoses and the radiator, but you will need to pressurize the system to find the source of the leak.

If you need some help with pinpointing the issue, consider enlisting a certified who can find find the coolant leak as necessary and diagnose the several other components I’ve mentioned above.

Good luck, and remember to change the thermostat even if you find a coolant leak.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: How do I stop my car from overheating?

Once the car is completely cool, check the coolant level in the radiator. If low, that will cause overheating. If it is low, you might have a leak that should be diagnosed. If the level of coolant is correct and...

Q: Transmission was slipping. Could it be the VSS?

Hi there. For the speedometer to be malfunctioning, either the vehicle speed sensor (VSS) could be loosing signal or the gauge has a bad resister. Now, as far as the transmission slipping, check the transmission fluid level. If the fluid...

Q: wind noise in doors

I'm not sure if the wind noise can be eliminated due to the shape of your 2005 GMC Envoy, but you may be able to reduce it to a more tolerable level. If you have a roof rack, I've heard...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...