5 Symptoms of an Overheating Car Engine (Do NOT Ignore These)

Concerned that your car is running hotter than usual? Engine overheating is a serious issue and should never be ignored. Fortunately, your vehicle often provides several warning signs before disaster strikes.

But beware! Not all signs are as obvious as you might expect, and some common beliefs about overheating are pure myth. Let’s look at the most likely symptoms and debunk some misconceptions about this potentially costly issue.

Table of Contents

Common Symptoms of Engine Overheating

Vehicle overheating is often accompanied by a number of secondary symptoms, a number of which tend to be relatively difficult to miss. Those who prove capable of identifying these symptoms are typically able to minimize collateral engine damage through their quick response.

#1 – Gauge/Temperature Light Feedback

One obvious sign of engine overheating surrounds the quick rise of the needle of the affected vehicle’s temperature gauge, or the sudden illumination of the temperature warning light.

Both of these functions serve as a visual aid to bring a driver’s attention to the overheating event that is taking place. But keep in mind that it’s possible for a temperature gauge to stop working correctly and you will have to rely on additional symptoms.

#2 – Appearance of Steam

Another classic sign of engine overheating is the appearance of steam billowing out from beneath a vehicle’s hood.

This can indicate that the cooling system itself has incurred a leak, or can signify that cooling system pressure has exceeded that for which the vehicle’s radiator cap was rated.

#3 – “Hot” Smells

Though somewhat elementary in concept, it bears remembering that all your senses can prove of value when attempting to detect overheating. In many instances, you can actually detect a burnt odor via their sense of smell when overheating occurs.

Under these circumstances, the odor of burnt rubber or plastic often becomes evident.

#4 – Appearance of Coolant On the Ground

If your vehicle has begun functioning erratically while in traffic, and a quick inspection has uncovered a puddle of coolant beneath the engine bay, overheating is likely to blame.

Further inspection should center around determining where the coolant in question was leaked from. But keep in mind that not all coolant leaks are obvious.

#5 – Abnormal Engine Noises

In many cases, motorists report hearing odd or abnormal engine noises as their vehicle begins overheating. This sound can vary from that of a thumping, to more of a consistent spewing or gurgling noise.

In any case, these noises come as the by-product of coolant flowing about in a superheated state.

What To Do When You Suspect Overheating

The first item of business when overheating is expected involves pulling over immediately to help make sure that the potential of engine damage is minimized.

An engine can become severely damaged in short order when operated in an overheated state. In many instances, the cost associated with rectifying this damage can far exceed the cost required to fix the root cause of the overheating itself.

If you are not immediately able to pull over in a safe fashion, turn your vehicle’s heat to “high” in order to dissipate thermal energy in the fastest way possible. Continue to look for a safe pull-off, and exit the roadway as soon as possible.

Once safely parked, turn the vehicle off at its ignition, and observe the scene. Look for signs of boilover, such as steam being emitted from beneath the hood.

Warning

Do not attempt to remove an overheated vehicle’s radiator cap for any reason. Trying to do so can result in severe burns or other forms of injury.

Wait for a vehicle's cooling system to completely depressurize before attempting any such actions. This depressurization can take an hour or more to occur.

Once the previously overheated vehicle’s radiator cap has been removed, top off the cooling system with coolant of the specified grade. Do not attempt to move the vehicle in question before doing so.

Note: If it's an emergency and you have no means of getting coolant, clean water (preferably distilled) may be added to the radiator. While not ideal, it's better than nothing.

Even after these steps have been taken, a vehicle should be moved no further than necessary to relocate it to an appropriate point to facilitate repair, as repeated overheating can occur.

Potential Consequences of Ignoring the Issue

Any form of engine overheating should never be ignored, no matter the severity. Overheating can quickly lead to severe internal engine damage, much of which often proves relatively costly to remediate.

On top of that, repeated incidences of overheating can prove every bit as detrimental as one prolonged overheating event.

Engine overheating, when ignored, can lead to an increased occurrence of head gasket failure and/or cylinder head cracking. Failures of this type typically require top-end overhaul to address, and can quickly exceed $1,000 in total repair costs.

Therefore, ignoring an overheating issue of any type can quickly equate to playing with fire, as well as extreme financial hardship.

If in doubt, always default to consult to receive a professional opinion regarding any and all matters surrounding evident engine overheating. Doing so can not only save you significant money, but prevent you from becoming stranded along the roadside in less than hospitable conditions.

Of course, those who are savvy in the DIY department might also consider taking a crack at addressing such issues themselves, often with a high level of success.

Preparedness and Prevention

There are several key points that motorists should keep in mind that will go a long way toward preventing incidences of overheating.

The first of these key points is that the value of periodic vehicle inspection should not be overlooked. Hoses, belts, and other critical components that make up a vehicle’s cooling system, or facilitate its operation, should be carefully inspected at every oil change interval.

System coolant levels should also be topped off. Any worn or otherwise compromised components found during inspection should be replaced immediately. Doing so can prevent untimely failure while in transit, along with the potential secondary damage that can occur whenever overheating takes place.

Simply put, replacing a radiator hose of questionable condition is cheap insurance against aggregating breakdowns.

One might also consider packing 2-3 gallons of distilled water in one corner of their trunk, especially when driving in extreme summer temperatures. This allows a motorist to refill their vehicle’s cooling system, in a bid to limp into the nearest town, should a coolant boilover take place.

This, in the long run, might save you from incurring an otherwise unnecessary wrecker bill.

Common Myths About Engine Overheating

Myth #1: The engine is overheating ONLY when steam or smoke is visible from the hood.

Fact: Engine overheating can occur without visible steam or smoke. Always monitor the temperature gauge for signs of overheating.

Myth #2: Turning on the heater will help cool down an overheating engine.

Fact: While turning on the heater can temporarily dissipate some heat, it is not a solution for an overheating engine and can be dangerous if the coolant is boiling.

Myth #3: Using water instead of coolant is a good solution for an overheating engine.

Fact: While water can be used in an emergency, it does not have the same heat transfer properties and corrosion protection as proper coolant. If you must use water, try to use the "distilled" variety.

Myth #4: It's safe to add coolant directly to the radiator of an overheated engine.

Fact: Never open a hot engine's radiator cap. Wait for the engine to completely cool down (it may take an hour) before opening the radiator cap and adding coolant to avoid injury from hot steam or coolant.

Myth #5: An overheating engine will always trigger a warning light on the dashboard.

Fact: Not all vehicles have a dedicated overheating warning light. The temperature gauge is the most reliable indicator of engine temperature but even it can be inaccurate.

Myth #6: Continuously revving the engine will help cool it down when overheating.

Fact: Revving the engine will generate more heat and can worsen the overheating problem. It's best to turn off the engine and let it cool down.

Myth #7: An electric cooling fan should always be running when the engine is on.

Fact: Electric cooling fans are designed to turn on and off based on coolant temperature and are not always running when the engine is on.

Myth #8: Engine overheating is a problem only in older vehicles.

Fact: While older vehicles may be more prone to cooling system issues, engine overheating can occur in vehicles of any age if proper maintenance is neglected or a component fails.

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Josh Boyd

Josh has worked as a full-time mechanic for over 12 years, with 6 ASE (Automotive Service Excellence) certifications under his belt. He began his career as an automotive technician at local Toyota dealership and has since transitioned to specializing in diesel trucks and equipment.