Car Overheating: What To Do in the Next Five Minutes

If the temperature gauge is climbing into the red or you see steam, this is the one symptom on this list where the next five minutes decide the size of the repair bill. An engine driven while overheating can warp its cylinder head or blow a head gasket - turning a hose or thermostat problem into an engine problem.

Do this, in this order

1. Pull over somewhere safe as soon as possible.
2. Shut the engine off and arrange roadside assistance; do not continue driving an overheating engine.
3. Let the engine cool completely before checking anything. A fixed waiting time does not guarantee it is safe.
4. Only when fully cool, check the coolant level in the overflow reservoir (the translucent plastic tank), not the radiator itself.

Never open the radiator cap or reservoir cap on a hot engine. The system is pressurized and the coolant is well past boiling - it can erupt and cause serious burns. No exceptions, no "just a quick peek."

Likely causes, cheap to serious

• Low coolant from a leak - a split hose, a tired radiator, a loose clamp.
• A thermostat stuck closed, so coolant never circulates to the radiator.
• A failing water pump, or a broken serpentine belt that drives it.
• Cooling fans not running - a dead fan motor, relay, or sensor (classic in stop-and-go traffic).
• A clogged radiator, or the serious end of the list: a blown head gasket.

Clues worth noting before you call anyone

• Overheats in traffic but cools at highway speed: airflow problem - fans or a clogged radiator.
• Overheats at speed too: circulation problem - thermostat, water pump, or low coolant.
• Sweet smell, white exhaust smoke, or milky residue under the oil cap: say so - it changes the diagnosis.