Skip the auto shop - Our mechanics make house calls

Q: Heat gauge is moving around rapidly to hot back to normal

asked by on

The truck seems to be running fine no issues I recently flushed the radiator yesterday and added a 50/50 mix thinking it may help the issue , I also turn the heat on when the high seems to rise but the vent produces cold air. It has only gone to where the warning light comes on twice but it will constantly go from a very acceptable level to a close to red no matter if i am going 35 or 70

My car has 274000 miles.
My car has an automatic transmission.

When you flushed the radiator, you may have not got enough fluid back into the engine and formed an air pocket. Try and see if the upper and lower radiator hoses are just as hot. If not, then the thermostat is stuck closed or blocked.

Also, when flushing the system the radiator may be partly clogged. If you have a temperature probe then measure the temperature at different parts of the radiator core to see if there are cold spots which indicate a partially clogged radiator. If you need help, have a mechanic come and diagnose your overheating problem for you.

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

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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: Truck stalled at 60mph on highway..restart attempts just click, starter contacts flywheel, but wont turn over.

That is not usually a good sign. If the starter engages the flywheel and the motor will not turn, you may have a bad starter, but since the vehicle stopped while running, it is a possible that the engine has...

Q: how to take the bottom bolt off the water pump?

The power steering lower bolt should be removed and the power steering swung out of the way. Then, using a 10mm swivel socket you can get the back bottom water pump bolts out without removing the front engine mount bracket....

Q: Won't run when warmed up

Hi there. It looks like you have inspected most of the common culprits of a choppy running engine. However, when the vehicle gets hot and has running issues, it's commonly caused by the EGR valve or EGR valve temperature solenoid....

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...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...