Engines get so hot under normal driving conditions that there is an entire system dedicated to cooling them down. That’s because an overheating engine will cause problems and even complete engine failure. Instead of shelling out thousands of dollars and enduring a ton of stress, here’s a primer on some common causes of overheating — and how to keep up with your cooling system before disaster strikes.
How Your Cooling System Works
The cooling system is relatively simple: A thermostat determines when the temperature is right to allow circulation. Once the car is warmed up, hot coolant flows from the engine through a radiator in order to remove heat from the liquid (by way of air and fan) before getting pumped back through the engine to cool internal components and pick up more heat before heading back to the radiator.
What Causes an Engine to Overheat
The most common causes of an overheating engine are:
- Low or leaking coolant
- A bad thermostat that won’t open to allow circulation
- Fan malfunctions that cause the fan to stop spinning or wobble
Other common causes might include a broken or damaged water pump belt that prevents proper pressurization and/or circulation, collapsed radiator hoses or a buildup of contaminants such as rust and road debris.
What You Can Do
The most important thing you can do for your cooling system is keep an eye on it. There is a temperature gauge on the dash to aid you, but it doesn’t hurt to pop the hood every now and then to make sure your coolant level is as it should be and to check on the fan belt condition. It’s normal to top off your coolant every so often, but if you’re having to do it regularly — or if you see a telltale puddle of coolant under your car — your system will need to be pressure-tested to locate any leaks.
If your vehicle overheats while driving, pull over and shut off the vehicle to assess the situation. Pop the hood and allow the engine to cool for 45 minutes. Opening the system and adding cold fluid while the engine is still hot is dangerous for both you and the engine. If there’s only a small leak, adding water will be good enough to get you to a NAPA Auto Parts store, but you’ll need to replace it with proper coolant so there’s no risk of damage in cold weather. If the level looks fine, carefully check the temperature of both top and bottom radiator hoses — if one is very hot and the other is not, this points to a thermostat that is stuck closed.
If you must drive, shut off the air conditioner, and turn on the heater. Granted, overheating is most common in the summer so this might be uncomfortable, but it will reduce the engine load and help allow heat to dissipate. If you’re driving at low speeds on roads that aren’t too bumpy, you can pop the hood without releasing the latch to allow a bit of extra air in that way. Ultimately, though, if you are out of coolant, no amount of tricks will save you. You will need to stop the vehicle, or risk severe engine damage.
Never remove a radiator cap while the engine is still hot! The system is pressurized, and hot coolant will spray out and onto your face and arms.
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Blair Lampe is a New York-based professional mechanic, blogger, theater technician, and speechwriter. In her downtime she enjoys backpacking wherever her boots will carry her, rock climbing, experimental theatre, a crisp rosé , and showering love on her 2001 Sierra truck.