We’re in a heat wave! What to do when your car overheats

With most of the country experiencing unusually high temperatures this week, it’s inevitable that many of us will have to deal with a car overheating.  “While it is rare for modern vehicles to overheat in hot weather, the two most common reasons for overheating are low water and coolant levels in the radiator or a leak in the cooling system,“ says Les Mc Master, Chairman of the Motor Industry Workshop Association (MIWA).


He says it’s important to check the coolant level. “If you aren’t sure where to look for the reservoir, check your owner’s manual. If the level is normal, you might just have a malfunctioning temperature gauge. However, if it’s low or empty there’s probably a coolant leak. In that case I’d strongly suggest you call roadside assistance. But if you have to keep driving, make sure the engine is cool, and protect your hand with a glove or a rag, then twist off the radiator cap. Refill both the radiator and the reservoir, using coolant or if necessary, water. This should bring the temperature down once you’re underway, but stay vigilant as you most probably have a serious leak somewhere.”


If the temperature starts rising again, pull over and repeat the process. But this is by no means a long term solution. “Get to an accredited MIWA workshop as soon as possible for the professional help your engine needs,” he says.


To prevent overheating, Mc Master advises regularly checking that your car has fresh coolant in its radiator, not just water, and also have the radiator checked for corrosion. However he cautions that even a well-tuned car may start to sizzle in hot conditions, particularly in stop-and-go traffic or when climbing a steep incline.


The first sign that your car is overheating will be your dashboard temperature indicator starting to rise or a malfunction indicator coming on. “The first thing you need to do is shut off the air conditioner and open the windows. This will help lessen the load on the engine and help it cool off. Although it sounds odd, it will also help to turn on the heater as this draws excess heat from the engine.”


If you’re in heavy traffic when this happens, shift into Neutral or Park and rev the engine just a little. This will make the water pump and fan speed up, drawing more liquid and air through the radiator. The increased air and liquid circulation helps cool the engine off.


Mc Master says brake drag also increases the load on the engine making it heat up. “If you are in traffic, rather crawl along slowly on little more than idle, than move up and brake repeatedly. Or move up only when the gap between you and the vehicle in front of you gets too large,” he adds.


The most serious indication that your car has already overheated is when the needle hits the red zone or you see steam coming from the engine. If this is the case, immediately find a safe place to stop, pull over and turn off the engine. “Just pulling over but still idling the engine is not enough. Engines have to work harder to keep cool at idle than at cruising speed, so turn it off as soon as you can,” he says.


Ideally you should then open the hood and wait for at least half an hour for the engine to cool off. “However be very careful when doing so, as it will be extremely hot underneath and you may need to wait for it to cool off a little first. Only then it’s safe to check the coolant level.”