• Overheating? What to do


    Recently, a discussion concerning “what to do if your car overheated” came up in our group. The topic came about when we were talking about an incident wherein a guy pulls up to a gas station (because his car was overheating), parks the car, pops the hood and the gas attendant immediately pours water into the radiator. Not sure though who told the gas attendant to pour water into the radiator, but the story goes that the gas attendant made a huge mistake. After everything, the engine was toast, resulting in a huge repair bill.

    So we were talking what exactly should one do if ever a car does overheat. Should you just turn off the engine and just let he engine cool down, or should you pour water into the radiator? Well, for starters, if your car does overheat, try and get off the road and if possible, try and park it where you will not be an obstruction to other vehicles. Once your car is in a safe location, turn the air-conditioning off and pop the hood to see what’s going on. If you have access to water (with the engine still running), start pouring water on the radiator, not only on the top portion but also try forcing water along the fins of the radiator. Also, check the coolant reservoir tank, (be careful as hot water or steam may come out) and make sure that it’s filled with water.

    Now, why would we need to fill up the reservoir tank, which is actually an expansion tank? When the coolant in the cooling system heats up, it expands. When pressure builds up, the radiator cap allows some of the coolant to leave the system and stay in the reservoir tank. Once the temperature of the coolant cools down, the coolant contracts and returns to the radiator. When this happens, there is actually less coolant in the system and a vacuum becomes present. The vacuum can cause the radiator to implode. How is that possible? The negative pressure created inside the radiator plus the air pressure out side. Now to prevent this from happening, the radiator cap will allow the coolant from the reservoir to return back into the radiator to fill up the vacuum. This is why we need to cool down the radiator by pouring water on it before we even think of removing the radiator cap. Note: if you notice that your reservoir is always full or empty when the engine is cold, better have the cooling system checked.

    What if we just turn the engine off and let it cool down? If there is no water available to cool down the radiator, then that’s it. That’s the only thing you could do. What will happen to your engine? Well, the engine can start to cook from the inside. The internal temperature has exceeded the normal working temperature of the engine. Both the steel and aluminum parts have been stressed thermally. At normal operating temp, both steel and aluminum will expand at a rate to keep them within a specified tolerance. Note: steel and aluminum have different thermal rates of expansion. And we haven’t looked at the gaskets and the oil seals and the oil itself. A lot of things get affected when an engine overheats. Reliability is compromised. It may not be evident now, it will bite you back somewhere down the road.

    So if your engine does overheat, try to cool it down as soon as possible to avoid damage to it. If you wish to share some insights or a question to be asked, Email me at drdavemech@gmail.com.


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