Mechanic Explains: What to Do When Your Car Overheats and What Never to Do
About this video
Car overheating? What you do in the next few minutes decides whether this is a cheap fix or a blown head gasket and a warped cylinder head. In this video an experienced mechanic covers what you should do the moment the gauge goes into the red, and just as important, what you should never do.
The mistakes at the bottom of this list are the ones that turn a 100 dollar thermostat into a 3000 dollar engine repair. Most people make at least two of them.
WHAT YOU SHOULD DO:
Turn off the air conditioning immediately
Turn the heat on full blast to pull heat out of the engine
Pull over safely as soon as you can and shut the engine off
Pop the hood release but leave the hood cracked, not fully open
Let it cool at least 30 to 45 minutes before touching anything
Check the coolant level once cool and top off if low
Look for steam, leaks, puddles or a burning smell
Restart and watch the gauge, and call for a tow if it climbs again
WHAT YOU SHOULD NEVER DO:
Never open the radiator cap or coolant reservoir while the engine is hot. The system is pressurized and boiling coolant sprays out under pressure and causes serious burns
Never keep driving to just make it home. A few extra miles can warp the cylinder head
Never pour cold water into a hot engine. Thermal shock can crack the block or head
Never spray water on the engine or radiator to cool it faster
Never ignore the gauge because the car still drives fine
Never remove the thermostat as a permanent fix
Never run plain tap water long term. Use the correct coolant type for your vehicle
Never assume it is fixed just because the gauge came back down
WARNING SIGNS YOU ARE OVERHEATING:
Temperature gauge climbing past normal or into the red
Coolant or engine temperature warning light
Steam or white vapor from under the hood
Sweet syrupy smell from coolant
Hot air stops coming from the heater
Loss of power or the engine going into limp mode
Ticking or knocking from the engine
Coolant puddle under the parked car
COMMON CAUSES OF OVERHEATING:
Low coolant from a leak in a hose, radiator or water pump
Stuck thermostat
Failed water pump
Radiator fan or fan clutch not working
Clogged or blocked radiator
Bad radiator cap that will not hold pressure
Air pocket in the cooling system after a coolant change
Failing head gasket pushing exhaust gases into the coolant
Collapsed lower radiator hose
RELATED FAULT CODES:
P0128 Coolant temperature below thermostat regulating temperature
P0116 through P0119 Engine coolant temperature sensor circuit
P0217 Engine over temperature condition
P0480 through P0482 Cooling fan relay circuit
Applies to nearly any vehicle, including Toyota, Honda, Ford, Chevrolet, GMC, Dodge, Ram, Jeep, Chrysler, Nissan, Hyundai, Kia, Subaru, Mazda, Volkswagen, Audi, BMW, Mercedes-Benz, Volvo, Lexus, Acura and Infiniti. Four cylinder, V6 and V8, gas or diesel, the cooling system works the same way.
A scan tool like the YOUCANIC UCAN-II Pro lets you read actual coolant temperature in live data, check fan commands and pull cooling system codes instead of trusting a dash gauge that may already be lying to you.
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