One of the scariest things to experience as a driver is seeing steam billowing out from under your hood like it's a boiling teapot. Fortunately, your car overheating doesn't mean it's time to start researching new cars , in most cases, a quick repair from your favorite auto repair shop will get you back on the road.
We've been helping people when their car overheats for 100 years, and we've gathered everything you need to know about possible causes, what to do and how to prevent it from happening again so you can drive with confidence.
Why Is My Car Overheating?
If your car is overheating, there's something wrong with your car's cooling system. Here are a few common culprits.
1. Coolant Issue
Coolant is a mix of water and antifreeze pumped through the engine to the radiator. As the coolant flows through designated channels within the engine block, it absorbs heat before passing through the radiator, where the fan(s) dissipate the heat.
One coolant issue may be an improper mixture of coolant and antifreeze. You can purchase coolant from an auto parts store as a premixed or concentrated formula. It won't function properly if you don't dilute the concentrated formula exactly as directed.
But in most cases involving coolant, the issue is low coolant. The coolant system is closed, so if you have low coolant, you have a leak somewhere in the system.
2. Thermostat Failure
The thermostat operates based on the engine's temperature and controls how much coolant to send through to return it to the proper temperature. The thermostat triggers a spring to open the plug when the engine reaches a specific temperature and then closes the plug when the engine is cooled.
The thermostat can fail to open and not allow coolant into the engine. In other cases, the spring controlling the plug breaks or gets stuck, allowing either too little coolant to cool the engine or too much coolant to enter the engine too quickly. Both failures will result in a car overheating.
3. Damaged Radiator
Coolant is pumped into the radiator after absorbing heat in the engine, and the radiator's fan blows air over the coolant to cool it. The hot air is then blown out of the car.
Several parts of the radiator can malfunction, causing a car to overheat:
- A cracked cap
- A leaky hose
- A broken fan
- A rusty radiator
It's important to change your coolant as outlined in your owner's manual to prevent these issues from occurring.
4. Faulty Serpentine Belt
The serpentine belt powers several of your car's parts, including the water pump. If the belt is damaged or loose, it may not be able to adequately power the water pump, slowing the movement of coolant through the engine and causing it to overheat.
5. Malfunctioning Water Pump
The water pump pushes coolant through the entire cooling system. Cracks in the water pump lower the pump's pressure, slowing the delivery of coolant to the engine. Most water pumps last about 60,000 to 100,000 miles, so check the serpentine belt first, since a faulty serpentine belt is more likely.
6. Clogged or Leaking Coolant Hose
Coolant hoses connect the coolant from the reservoir to the engine to the radiator. At any point, these hoses can become clogged by dirt or debris , especially if you're using the wrong coolant , or crack and leak. Either way, enough coolant won't move through the system, causing the engine to overheat.
7. Blown Head Gasket
The head gasket is the seal between the engine and the combustion chamber. It operates in extreme temperatures to maintain pressure from the combustion chamber and prevent engine fluids like coolant from leaking. It can leak or crack due to normal wear and tear over time.
8. Low Oil Level
While not technically part of your cooling system, low oil can also cause your engine to overheat. The oil acts as a lubricant, allowing the engine's moving parts, such as pistons and valves, to move with less friction. If you don't have enough oil, the moving parts create more friction, raising the engine's temperature.
To prevent this, get regular oil changes.
7 Signs Your Car Is Overheating
If your car is overheating, you'll experience one or all of the following signs.
1. Illuminated Temperature Gauge
Cars have a temperature gauge on the dashboard. On some vehicles, this gauge is similar to the fuel gauge, with a needle that moves between cold and hot. If the needle reaches the red part of the gauge, your car is overheating, and you should pull over and turn the engine off immediately. In other vehicles, you'll see a thermostat indicator light illuminate when the car is overheating.
If everything functions normally, this should be the first indication that your car is overheating. However, this warning sign only works if your car's thermostat is working, so don't rely on it. If you see other signs of overheating but your temperature gauge is not indicating an issue, you should still pull over and turn the engine off.
2. Burning Smell
As your engine heats, many of the plastic and rubber components will start to melt, emitting a burning smell. When coolant burns, it smells sweet.
If your heat or air conditioning is on, they will pull the scents directly into the car through the HVAC intake located near the engine. If you notice this smell, open the windows immediately to disperse any potentially harmful fumes.
3. Thumping or Ticking Sounds From the Engine
When the thermostat fails and keeps the coolant in the engine too long before letting in new coolant, you'll hear a thumping noise as the boiling coolant mixes with the cooler liquid. If the engine has a lubrication problem, you'll hear a ticking sound as the moving components swell in the heat and bump against each other.
4. Coolant Under Your Car
The cooling system is a contained system, so you should never see any coolant under your car. If you do, there's a leak somewhere in the system. To determine if the liquid under your vehicle is coolant, check its color and smell , coolant can be yellow, orange, red, green, blue or violet with a sweet odor.
5. Steam From Underneath the Hood
If coolant is leaking from the cooling system while the car is running, it will create steam. Coolant is half water, so when it leaks onto overheated engine components or is exposed to overheated air, it will boil and create steam.
6. Decreased Engine Power
As the engine overheats, the components within will expand, causing performance issues such as decreased acceleration. If you find yourself needing to use more gas than usual to accelerate, an overheated engine may be the culprit.
7. Extremely Hot Hood
A normally functioning car engine runs at about 195-220 degrees Fahrenheit, so your hood will always be hot to the touch when it's running. However, you should be able to leave your hand on the hood for at least 10 seconds. If you can't, your engine is likely overheating.
What To Do If Your Car Overheats
If you notice signs of your car overheating, follow the steps below.
- Pull over safely. Turn on your hazard lights as you slow down and make your way to the shoulder or a less busy side street or parking lot.
- Turn off your engine. As soon as you are pulled over, turn off the car to prevent further damage.
- Move to a safe location. Exit the vehicle with any passengers and move to a safe location away from the roadway. This will limit your chances of getting hit by a passing car.
- Call roadside assistance. To prevent further damage to your car, call roadside assistance for a tow to the nearest auto repair facility. Attempting to add coolant to your vehicle yourself and continuing to drive is dangerous and can cause severe burns and potentially thousands of dollars of damage to your vehicle.
How To Prevent an Overheated Engine
While a car overheating can happen to anyone at any time, there are ways to minimize your risk.
- Check fluid levels regularly. Regularly check fluid levels to ensure they are always within normal levels. Most auto repair facilities check your fluid levels as part of a standard oil change, but you should also check once a month between oil changes.
- Monitor your car's temperature in hot weather. Excessively high temperatures can add to the heat produced by your engine. During hot weather, keep an eye on your car's temperature gauge when driving and consider turning off the AC to reduce stress on your engine.
- Get regularly scheduled maintenance as outlined in your owner's manual. Adhering to the manufacturer's maintenance schedule can catch minor issues before they become problems that cause your engine to overheat.
- Drive patiently in stop-and-go traffic. Stop-and-go traffic puts more stress on the engine than driving on the highway since the engine idles more. Avoid accelerating quickly and slamming on the brakes as much as possible whenever you drive, especially on hot days.
Keep Your Engine Running With AAA
If your car overheats, give AAA roadside assistance a call. We'll tow you to the closest auto repair facility, where you can use your AAA membership to save at least 10 percent on labor costs on any coolant system repair. Our AAA Approved Auto Repair facilities are staffed by certified technicians, so you can rest easy that your car is repaired correctly.