Common Reasons Your Car Overheats

It’s summer and everyone’s seems to be having fun outside with the temperatures rising after a long cold winter. However, unlike the summer, it’s not nearly as exciting when your car overheats. Your car can overheat for a number of different reasons and that’s why we’re here to help you diagnose the problem early and snip it at the bud to avoid a possibly expensive repair bill.

If your car overheats at idle and cools down when it’s running, then more often than not, it’s an issue with your fan, however, it’s difficult to ascertain exactly what’s causing this and how it can be fixed without knowing the make and model of the car with the issue. But we can still perform a rudimentary diagnosis based on what we know about the common reasons your car overheats. While an issue with the fan is the most common reason car owners face overheating issues, other issues such as those with low
levels of coolant or malfunctioning temperature sensors and gauges cannot be completely ruled out just yet. To narrow down on what the issue could be, check the components below in the given order:

  • Check your coolant level is sufficient after turning the engine off and allowing it to cool down for a bit. Never try to do this when the engine is still hot. Air bubbles in the coolant can also cause the car to overheat. Always make sure to only use the specific kind of antifreeze as suggested by the manufacturer. 
  • Fan belts (if your fan is driven by one) can cause overheating problems if they are loose or frayed. This would require replacing the belt. 
  • If you have an electrically-powered fan, make sure it’s connected and not burned. One way to check if the fans are working is to turn on the air conditioning unit to see if the fans turn on as well. If your car has passed all of these tests and still continues to overheat, then it could be an issue with the wiring that connects the fans, or the switch or even the radiator.

Understanding why cars overheat at idle

Car cooling systems work by constantly pumping hot coolant through the radiator, which transfers the heat to the air and this pumping is done a lot more easily when the car is in motion, which is why cars are more susceptible to heating problems when they are at idle – simply because it takes more energy and effort for the car to pump the coolant through the radiator when it is idle. To help make it easier for the pumping mechanism, the fan blows air through the radiator. It’s easy to see how an issue with the fan
could make the radiator much less efficient than it already is when it’s at idle.

Checking the coolant

If your engine is overheating when it idles, it’s important that you avoid driving in bumper-to-bumper traffic conditions, because your engine will have no time to cool down, at least until you have it looked at by a technician.

Before you can get your car looked at by a professional, you can perform some basic checks yourself like checking the coolant. It’s VERY important that you don’t mess with anything under the hood (and especially not your coolant reservoir because the extremely hot coolant can blast in your face as its pressurized from the heat) until the engine cools down. You can tell if it’s too hot to be messing with if the hoses feel hot and look taut. Once the engine has cooled down, go ahead and check if the coolant level is sufficient and if it isn’t filled it up.

Checking the concentration of antifreeze

Coolant is made up of a mixture of antifreeze and water. The antifreeze component keeps the coolant from freezing and the water
helps in dissipation of heat, thereby making it good for when it’s too hot or too cold. Some overheating woes can be caused by the concentration of antifreeze in your coolant exceeding that of water, this can be dealt with by simply draining some of the coolants out and adding water to it. Use an antifreeze hydrometer to ascertain the correct concentration of water and antifreeze.

Checking belts of belt-driven fans

Cars with longitudinal engines often use belt-driven fans instead of electrically powered ones. When you open the hood, you should
see a fan attached to a pulley system through a belt, either with a fan cluth, or without. If there is no fan clutch, checking and replacing any loose and/or frayed belt should help fix the overheating issues. However, if there is a fan clutch that activates the fan only when required, then troubleshooting the issue will be less intuitive and more complicated, so the most you can do without having a mechanic look into it at this point is seeing if the connections are in place like the should be.

Checking electrically powered fans

Cars whose fans are powered electrically are designed to automatically switch on when the airflow to the radiator is insufficient. In
cars with such fans, the easiest way to tell if your fan is malfunctioning is to simply check if the fans are off when the engine is overheating. This could either mean that the fan is burned out or that there is no power supply to the fan. A simple but effective test to check if the fans are working is to turn on the air conditioning unit, if the fans don’t turn on then that indicates a problem with it.

Emergency fixes

If you’re stuck in endless traffic and there’s no way out but to push through it, turning on the air conditioner might force the fans to engage. Another emergency fix that goes against conventional knowledge is to turn the heat in your car own, as the heater is basically a miniature radiator that extracts heat from the coolant and transfers it into your car. Do this while you call the nearest repair shop informing them of your situation and it might just be able to help you last long enough to get out of the jam.

If your car is overheating while in motion, then try all of the methods suggested above and if it still fails, you’ll have to call a professional to get it looked at as it could be a more serious issue or symptom of an underlying issue that could potentially make it unsafe for you to drive around in such a condition. We hope this guide has been of value and helped you fix your overheating car. However, if it hasn’t, then we’d strongly recommend calling a mechanic and having your car looked at before you can use it.

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