Severity Level: High – Have this checked out immediately
Why is my car overheating?
An internal combustion engine – the type found in most cars, trucks, and SUVs on the road today – produces a lot of heat. Some of the heat is normal and necessary for peak engine performance. But too much heat can damage your engine.
To know why your car might overheat, it is important to understand the system that prevents an engine from getting too hot, along with the likely causes of car overheating.
The engine cooling system
Vehicles with internal combustion engines are fitted with a cooling system. This system serves to regulate engine operating temperatures so that they remain within a specific range.
Most engines prefer to run within a specified temperature range. If your engine is unable to get up to its minimum operating temperature, it will not burn fuel efficiently. Fortunately, that is usually not a problem, since friction from the moving parts inside (not to mention the combustion process itself) provides plenty of heat in a short amount of time. But if your engine gets too hot for too long, significant damage can occur.
The cooling system works by circulating a mixture of water and engine coolant (also known as “antifreeze” for its ability to resist freezing in winter) throughout the engine block. On its way through, the coolant mixture absorbs heat before exiting the engine. The hot coolant makes its way through a hose to the radiator, where much of the heat is able to dissipate with help from the cooling fans. Now cooled considerably, the coolant makes its way back to the engine to pick up more heat.
The engine coolant is forced through the system by the water pump mounted on the front of the engine block. The pump is actuated by a serpentine drive belt that itself is driven by a pulley on the engine crankshaft. On some vehicles, the water pump is mounted inside the engine and is driven instead by the timing belt or timing chain. As it makes its way, some of the hot coolant is diverted into the passenger compartment where it is used to warm up the cabin. A thermostat is a type of valve placed in the coolant stream. It opens to cool your engine and closes to allow it to warm up.
Causes of car overheating
There are several potential causes of an overheating car. That is because there are so many components that cooperate to keep your engine cool. Among the most common causes of engine overheating are:
- Failed water pump. If the water pump is unable to force the coolant through the cooling system, heat will build up in your engine and it will overheat.
- Bad thermostat. A thermostat that is stuck in either the open or closed position can cause problems for your engine. If it remains closed, your engine will likely overheat.
- Coolant leak. If the coolant is allowed to leak from the system, it will fail to circulate and absorb sufficient heat to keep your engine cool. Coolant leaks can happen at many points in the system, including the radiator, hoses, heater core, and seals in the engine itself. If a seal inside the engine allows coolant to leak into the crankcase where the oil resides, not only can your engine overheat, but other problems can occur as well.
- Broken serpentine belt. Since the serpentine belt drives your engine’s water pump, coolant will be unable to flow if it breaks. The problem is similar (although simpler) to that of a failed water pump. If, on the other hand, the pump is driven by a timing belt or chain, the problem can be far worse if the belt/chain breaks.
- Inoperative cooling fan(s). The cooling fans help to move air through the radiator so that the heat from the coolant can dissipate. This is especially needed when your vehicle is standing still and idling. If the fan does not work, your engine can overheat.
- Clogged radiator. A leaking radiator is a problem. So is one that is clogged with debris due to poor maintenance. If the radiator is plugged, coolant will not flow through, and your engine will overheat.
- Low oil level. One of the duties of engine oil is to help keep your engine cool. It does so by reducing friction between all of the moving parts inside. If the oil level drops (something that is all too common), or if the oil degrades too much (as it tends to do over time), it will not contribute as it should to keeping your engine cool.
How do I know if my engine is overheating?
Just as there are a number of causes of an overheating engine, there are also several possible signs that your engine has overheated.
Signs of an overheating engine
- A dashboard warning light or temperature gauge signals that engine temperatures are rising.
- You notice a burning smell or the syrup sweet odor of engine coolant.
- You see steam coming from under the hood.
- You hear a ticking sound coming from the engine.
- You see engine coolant pooling on the ground.
- The hood seems hot to the touch (in this case, do not open the hood).
- Engine power is significantly reduced as the ECM (engine control module) adjusts to prevent damage.
- The check engine light comes on.
Is it okay to drive if my engine overheats?
If you are wondering how far you can drive with an overheating car, understand that driving with that condition places undue strain and stress on your engine. This can lead to considerable damage – even a total loss of your engine. Therefore, you should never drive if the engine is overheating.
Instead, pull over as soon as it is safe to do so. Get in touch with a roadside assistance service to have your vehicle towed to a trusted repair shop. It might be quite difficult to drive your vehicle with an overheated engine anyways. That is because vehicle manufacturers program a failsafe into the system. When the ECM detects that your engine is staying too hot, it places the engine into “limp mode”, limiting operation to low RPMs and slow speed. The purpose is not to help you drive home but to get you safely off of the road to a place where you can park.
If your engine overheats, let it cool down. How long does it take? Usually about a half hour or so. Under no circumstance should you attempt to remove the radiator cap or otherwise open up the cooling system. Serious danger from scalding steam can cause injury.
Can your engine survive overheating? Probably. As long as you do not attempt to drive while in that condition. Significant overheating, on the other hand, can lead to all sorts of engine problems. These range from warped cylinder heads to damaged pistons and valves. The engine block itself can crack. And an engine fire is possible. Better to avoid driving if your engine overheats.
How can I tell if my engine is damaged from car overheating?
Signs of damage to your engine from overheating might not be as obvious as the symptoms of overheating. Some of the signs can be attributed to other issues. For instance, an oil leak can come from any number of failed seals or faulty components, but it can also be caused by a cracked engine block due to overheating. Some of the signs might be minor and undetectable. Others are major, whether they are easily detected or not. Your best bet is to have your vehicle evaluated by a technician if you suspect that it has overheated.
Potential problems due to overheating include an engine knock. This is a condition that happens when fuel burns erratically or prematurely inside a cylinder. Knocking adds stress on an engine. Driving with this condition is detrimental and can lead to further engine damage.
Another sign of engine damage from overheating is fluid leakage. Coolant and oil can leak from cracks or blown seals that happen when an engine overheats. Look for pooling on the ground or inside the engine compartment.
The cylinder head sits on top of the engine cylinders. When an engine overheats, the cylinder head can warp or crack. This can lead to a loss of compression and internal fluid leaks. The head gasket can also fail and lead to the same problems.
Other internal components that might receive damage include the pistons and exhaust valves. But unlike the previous problems, damage to these parts is more difficult to identify and diagnose.
How do I prevent car overheating?
Engine overheating is a cause for concern. You should not drive your vehicle for long if the engine gets too hot. But how might you keep it from overheating in the first place?
The best way to prevent an overheating engine is to pay attention to the vehicle manufacturer’s recommended maintenance schedule and follow it closely. You can also avoid leaving your car in the heat for long periods of time. And you can keep an eye open for signs of problems that lead to overheating.
Here are a few tips to keep your car from overheating:
- Change the engine oil and filter regularly
- Make sure that the engine coolant is topped off and note if the level drops
- Look for signs of fluid leaks on the ground
- Consider a coolant flush to keep the system clean
- Replace a run down battery
- Listen for odd noises, like a squealing serpentine belt or water pump
- Pay attention to any strange, syrupy coolant odors
- Keep an eye on the engine temperature gauge
- Park in the shade when possible
Repair services related to engine overheating
Engine overheating FAQs
Why is my car overheating?
Your car can overheat for a number of reasons, including a coolant leak, bad cylinder head, failed water pump, or poor vehicle maintenance.
How do I know if my engine is overheating?
Signs of an overheating engine include a warning light or temperature gauge on the dashboard, steam coming from underneath your hood, the syrupy sweet odor of engine coolant, a fluid leak on the ground, and more.
Is it okay to drive if my engine is overheating?
No. Do not drive any more than necessary if your engine overheats. Pull over to a safe location. Driving while your car overheats can cause significant engine damage.
How long does it take for an engine to cool down after overheating?
It usually takes about a half hour or more for an engine to cool down enough to be safe for inspection.
Can my engine survive overheating?
If an engine is allowed to run for very long after overheating, damage can occur. In some cases, that damage can be catastrophic. If you are able to turn your engine off in short order, it can survive the event.
How can I tell if my engine is damaged from overheating?
Signs of engine damage often require a professional diagnosis. Have your vehicle towed to a trusted repair shop for evaluation if the engine has overheated.
