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: Tried adding refrigerant and it wouldn't take any

Hello. Air conditioning systems on newer cars, trucks, and SUV's are incredibly complex. However, the issue you're describing may be caused by a high pressure or low pressure hose that is damaged or leaking. When the hose is clogged or...

Q: 97 Pontiac firebird formula brake light issues.

You will need to check the brake lights for power to the lights from turn signal switch. The third brake lights come direct from brake light switch where the lower brake lights have to go through the turn signal switch...

Q: 06 dts 110k new plugs and packs started idle shuttle hesitant at first then stops bought car used i believe fuel filter is origina

Hello, thanks for writing in about your Cadillac DTS. The fuel filter and fuel pump may be the cause of this issue. You should have the fuel pressure tested first to see if the fuel pump is failing. Replace the...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.