For the experienced DIYer, dealing with engine overheating may appear to be a pretty simple set of causes and effects. But for newbies to the home auto maintenance game, gushing steam and hot liquid blowing out of the engine compartment can be a frightening experience.
As a result, we thought we’d take a look at this scenario with an eye toward understanding why engines overheat, what parts are involved, what triggers lead to the event, and how you can handle the problem -- whether it’s in the driveway, or more importantly, on the side of the road.
Signs Your Engine Is Overheating
Awareness is key when it comes to detecting an overheating engine. Knowing the signs that indicate your engine is running too hot can help you address the issue promptly and help prevent potential damage.
Keep an eye out for these telltale signs that your vehicle's engine may be overheating.
Steam or smoke coming from the engine. One of the most obvious signs of an overheating engine is steam or smoke coming from the engine compartment.
High temperature gauge reading. Most modern vehicles are equipped with dashboard temperature gauges. If the gauge reads red or the needle is in the hot zone, the engine is overheating.
Illuminated warning light. Many vehicles are equipped with a warning light on the dashboard. If this device illuminates, the engine is overheating.
Loss of power. If your car loses power, becomes sluggish or is unresponsive, the engine may be overheating.
Odd odors. An overheating engine can produce strange smells like burning oil or coolant.
Loud knocking or ticking noises. In severe cases, an overheating engine may produce loud knocking or ticking noises.
What To Do If Your Engine Starts Overheating
If you experience engine overheating while driving, there are critical steps you should take to ensure the safety of you and anyone else in the vehicle – as well as the vehicle itself.
First things first, get off the road. You want to pull over to a safe location, preferably a level, open area that is away from traffic. Once stopped, turn off the engine. This will help prevent further damage and reduce the risk of a fire.
If you can safely pop the hood from the driver’s seat, do that next to help the heat escape. If your vehicle does not have this option, then let engine cool down before opening the hood. This can take as much as 30 minutes. Be sure to use gloves or a rag to protect your hands from hot components.
Once the engine has cooled down properly, check the coolant level. If it's low, add coolant to the system. Wait for the engine to cool down completely before driving again. This can take up to an hour.
Keeping your cool when the engine is overheating can be difficult, but remembering what not to do is equally important.
DO NOT… continue driving. If you notice signs of engine overheating, it is imperative that you stop the car. Driving an overheating engine can cause serious damage and potentially lead to even more dangerous situations.
DO NOT… remove the radiator cap. If the engine is hot, the pressure in the coolant system can cause hot coolant to spray from the radiator flange once the cap is removed. This can cause serious burns and injuries. Always wait for the engine to cool properly before removing the radiator cap.
DO NOT… pour cold water on a hot engine. Pouring cold water on a hot engine can cause rapid temperature changes that can damage engine components. Instead, wait for the engine to cool down naturally.
DO NOT… drive with low coolant levels. If the engine is overheating due to low coolant levels, do not continue driving. Low coolant levels can cause extended damage to the engine.
DO NOT… ignore warning lights or mechanical symptoms. If you notice anything that relates to engine overheating, including a high temperature gauge reading, or the illumination of a warning light, do not ignore them. Ignoring these elements can lead to serious engine damage and expensive repairs.
Why Do Engines Overheat?
Now that you know what to do in an engine overheating scenario, let’s investigate what actually causes this malfunction to occur in the first place.
Generally, when it comes to overheating, there is more than a single component involved in the failure. Consequently, it’s important to recognize what parts apply to this condition, particularly from a DIY perspective.
The usual problem area is the cooling system, which includes the radiator, water pump, thermostat, hoses and coolant itself. The radiator is the key component in this system, dissipating heat to keep the engine at optimum operating temperature. It houses a cooling tube complex that allows coolant to circulate throughout the engine to absorb heat during operation. This hot liquid then returns to the radiator, where the heat is exchanged with cool air outside the vehicle.
The thermostat is comprised of a temperature-sensitive spring and a stopper. When the engine is cool, the stopper keeps coolant from moving in and around the engine complex. When engine temperature increases, the spring releases and opens the stopper, thereby allowing coolant to move throughout the radiator and the engine complex. The water pump has the job of actually pushing the coolant from the radiator, throughout the engine complex and then back to the radiator. The cooling fan increases airflow across the radiator face, thereby enhancing the radiator’s dynamic cooling.
The head gasket can sometimes be the issue in an engine overheating situation. Sitting between the engine block and the cylinder head, it is a critical device whose goal is to support and maintain proper combustion pressures, while also avoiding the escape of various liquids from within the engine block.
Lastly, the exhaust system can occasionally cause a problem too. Defined by a pipe complex supported by several affiliate components, its job is to channel gases and harmful emissions away from the engine, ultimately trapping them and/or expelling the remainder into the atmosphere outside the vehicle.
Although there is usually a central component malfunction related to overheating, there can also be multiple triggers that lead to the failure.
The most common culprits for engine overheating are:
Low coolant level. If the coolant level is low, there may not be enough fluid to establish a proper engine temperature.
Malfunctioning thermostat. The thermostat regulates coolant movement throughout the engine complex. If it is malfunctioning, temperature changes could become erratic.
Malfunctioning water pump. The water pump circulates coolant through the engine. If the pump fails, coolant may not flow properly and the engine can overheat.
Blocked radiator. The radiator is responsible for dissipating heat by means of coolant supported by airflow. If it is blocked with clag, sediment or corrosion, cooling efficiency may be reduced, causing the engine to overheat.
Faulty cooling fan. The cooling fan helps dissipate heat across the radiator face. If the fan fails, the engine can experience an over-temp condition, ultimately leading to overheating.
Hose or fitting leaks. Coolant leaks can reduce fluid volume and ultimately create overheating.
How Do You Prevent Engine Overheating?
There’s a reason they say prevention is the best cure. An overheating engine is a stressful scenario – one that can quickly lead to expensive repair costs. Avoiding this headache in the first place is the simplest and most cost-effective way of safeguarding both you and your vehicle.
Be sure to check coolant levels regularly, since this vital fluid regulates engine temperature. When it gets low, top it off and take care to use the proper formula per your owner’s manual. Also, keep in mind that coolant breaks down over time, causing it to lose its effectiveness. So, be sure to replace coolant regularly, again based on the recommendations provided in your owner’s manual.
Monitor the thermostat in your vehicle, as well, since any sudden problems with engine temperature will register here first. Look out for sudden spikes and drops or consistently high temperature readings, as these could be symptoms that the thermostat is starting to fail.
Filling Auto Coolant
Other useful hands-on maintenance tips are to keep the radiator face clean and free of debris to ensure proper airflow and to regularly inspect hoses and fittings for signs of wear or leaks.
If you’d rather save ‘under-the-hood’ inspections for qualified technicians, there are still plenty of things you can do as a driver to help prevent your vehicle’s engine from overheating.
When taking long drives or just operating the vehicle on particularly hot days, limit A/C usage when possible. While a delightful modern convenience, air conditioning pulls a lot of engine load. If you’re worried the engine is getting hot, you can try lowering the vehicle’s windows and then turning on the heat. This can help offload some of engine’s heat by pulling it into the cabin and then pushing it outside.
Taking periodic breaks on long drives can help too, along with parking in the shade.
Another form of prevention involves being prepared for the worst. Engine overheating while driving represents a pretty serious safety hazard. Consider keeping a well-stocked car emergency kit on board, complete with safety triangles or flares, water or coolant, gloves, a rag, and a small fire extinguisher.
What Should You Tell The Technician?
Sometimes you just can’t resolve a problem when you’re sitting on the side of the road. This means that you’re going to experience seeing your car sitting in an auto bay somewhere while a technician pours over your pride and joy.
Don’t be intimated; you have all the information the tech will need to get started. Here are some things you should offer to get off on the right foot:
Symptoms you experienced. Explain your experience, such as seeing steam or smoke coming from the engine, a loss of power, strange smells, or describe any strange noises. Be as specific as possible and offer any other relevant details as well.
When the issue occurred. Tell the tech when the event occurred, such as on a long drive, in heavy traffic or during a hot day. This can help identify a potential cause.
What you did to address the issue. Explain what steps you took, such as pulling over, adding coolant or water.
Any recent maintenance or repairs. Specifically tell the technician about any recent maintenance or repairs. This information can help them identify and focus on a potential cause more quickly.
Any changes in driving habits or conditions. Explain any recent changes in driving habits or if you've been operating in different conditions than normal. This can also help the tech diagnose the issue more quickly.
Hopefully this information will be useful, whether you’re trying to diagnose an overheating problem yourself, or if your car is at the shop. Nevertheless, issues of overheating are important telltale events, so don’t wait to resolve a problem before things get any hotter than they already are.