Skip the auto shop - Our mechanics make house calls

Q: Overheating for no apparent reason suddenly and after a longer drive

asked by on

My car that has around 150,000 miles on it keeps overheating for no apparent reason. It suddenly starts showing that it reached the hot zone when I just start driving. When it happened a couple of times, my AC used to blow hot air instead of cold. Now it blows cold when it is overheated.

I've had all kinds of testing, from coolant checking to bleeding the coolant system, replacing the radiator cap, changing the thermostat. Also, the water pump was replaced. After that, while driving around town, it ran great so I decided to go to a longer trip. Then it started overheating again. It happened after about 25 miles of driving to the point that it couldn't be driven anymore. Please give me some advice on what to check next.

Hi there. It sounds like you may have a blown head gasket. This is typically the only thing that will allow the engine to overheat that fast. When the gaskets begin to leak, it will allow combustion pressure to enter the cooling system causing this to overheat. I typically start by doing a block test to see if there is any exhaust gases getting into the cooling system. I will also use a 5 gas analyzer if the block test does not show anything positive. If the head gasket is fine, then I would suspect that there is some blockage in the radiator that may need to be replaced. If you want to have a certified mechanic verify the faulty component, a technician from YourMechanic can come to your home or office to diagnose your car’s overheating problem and perform needed repairs.

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!
  • Home
  • Questions
  • Overheating for no apparent reason suddenly and after a longer drive

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: Replace Radiator - do I need to purge/recharge the AC system?

Hello. When replacing the radiator, you do have to mess with the condenser a little bit, but you do not need to disconnect it or remove it. The first step when it comes to the condenser is to remove the...

Q: My car overheating after 8-10 km on ac i was replaced radiator waterpump and remove thermostat wall now. What can i do

Usually the radiator and water pump are the culprits with symptoms like this. The condenser sits in front of the radiator and it gets hot when the A/C is on. Like the radiator, it relies on air flow to cool....

Q: I get a squeaky noise when I turn right or come to a stop.

The first thing that comes to mind would be lower ball joints. It's not uncommon for ball joints, tie rod ends and brakes to exhibit similar sounding squeaks, although lower ball joints are the most common culprit for squeaking when...

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
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...