An overheating engine is one of the most damaging problems your car can have. Drive an overheated engine for even a few minutes and you can warp the head, blow the head gasket, or seize the engine completely. The repair bill on a destroyed engine often exceeds the value of the car.
Warning Signs Your Engine Is Overheating
- Temperature gauge climbing into the red zone
- Steam or smoke coming from under the hood
- Sweet smell (coolant) inside or outside the car
- Coolant warning light on the dashboard
- Engine running rougher than normal
- Heater blowing cold air
What to Do Right Now If Your Car Is Overheating
- Turn off the AC, turn on the heater full blast. The heater pulls heat from the engine.
- Pull over as soon as safely possible.
- Turn off the engine and let it cool for at least 30 minutes.
- Do not open the radiator cap while hot. Pressurized coolant can spray and cause severe burns.
- Once cool, check the coolant level. If low, you have a leak.
- Call for a tow if you cannot safely reach a shop.
Most Common Causes
Low Coolant or Leak
The simplest cause. A leak in the radiator, water pump, hoses, or heater core can drain coolant until the system cannot cool the engine.
Cost to fix: $50 to $1,200 depending on what is leaking.
Failed Thermostat
A stuck-closed thermostat blocks coolant flow, causing rapid overheating. A stuck-open thermostat does not overheat but causes other issues.
Cost to fix: $150 to $450.
Failed Water Pump
The water pump circulates coolant. If the impeller breaks or the pump leaks badly, the engine overheats.
Cost to fix: $400 to $1,000.
Bad Radiator or Cooling Fan
Clogged radiators or a failed cooling fan cause overheating, especially in stop-and-go traffic. If your car overheats at idle but is fine on the highway, the cooling fan is the prime suspect.
Cost to fix: $300 to $1,200.
Blown Head Gasket
The worst-case scenario. Symptoms include white smoke from the exhaust, milky oil, coolant disappearing with no visible leak, and bubbles in the coolant reservoir.
Cost to fix: $1,500 to $3,500 plus.
How to Prevent Overheating
- Flush coolant on the manufacturer schedule, usually every 60,000 to 100,000 miles.
- Inspect hoses and the radiator yearly for cracks, soft spots, or leaks.
- Replace the thermostat any time you do major cooling work, it is cheap and a common failure.
- Address any small coolant leak immediately, do not just top up.
Get a Repair Estimate Before Approving Work
Cooling system repair costs vary wildly between shops. Get a free AI estimate before authorizing, especially for water pump or radiator jobs where the labor portion is the biggest part of the bill.