While you can manage to drive with some problems in your vehicles for an extended period, car engine overheating isn’t one of them.
Driving with an engine overheating is a quick way of sending your engine to a junkyard. That’s why it’s crucial to identify and rectify any engine overheating issues before hitting the road.
In this article, I’ll explain what causes a car to overheat while driving and the possible solutions. You’ll also learn how to diagnose overheating engines.
By the end of this article, you will know the possible car overheating causes and the best solutions. But first, let’s see the reasons why a car overheats in the first place.
Understanding Car Overheating
A combustion engine operates by harnessing the power from several hundred miniature explosions every minute, and to avoid a major catastrophe in a short time, the cooling system circulates coolant throughout the engine and carries it away to be dispersed into the atmosphere.
However, over the course of time, it might not work as well as it used to, and overheating is the result.
A car’s engine can overheat due to several reasons, ranging from simple to complex. The primary cause is often insufficient cooling, and primarily because the coolant isn’t properly circulating. The other major cause is because there isn’t enough coolant in the system.
Common Causes of Car Overheating
The most common reasons for a car engine overheating are low engine coolant, a faulty thermostat, coolant leaks, radiator problems, a failing water pump, and a lousy engine cooling fan.
However, there are other possible causes, such as air pockets in the coolant, low coolant pressure, and low engine oil.
Let’s look at these possible engine overheating causes one after the other for a clear understanding of how they affect the engine temperature.
#1. Low engine coolant or no coolant.
The primary role of an engine coolant is to cool down the engine. So, in reality, if there’s low or no engine coolant, it’ll cause the engine temperature to rise more than it should and cause overheating.
If your engine coolant is going down regularly, you need to check where the coolant is going.
However, there’s a normal coolant loss. This implies that your engine coolant will reduce over time, but not regularly.
#2. Faulty thermostat.
The thermostat allows the engine coolant to travel from the radiator to the engine. The thermostat stays closed when the engine is cool and opens when the engine gets to the average operating temperature.
In other words, the primary function of the thermostat is to allow the engine get to the average operating temperature and prevent it from overheating. If it’s stuck closed, the engine will overheat.
#3. Lousy water pump.
As the thermostat allows the coolant into the engine, the water pump circulates the coolant to every part of the engine that needs it.
If it fails, the coolant will stay stagnant in the engine, which will invariably cause engine overheating. While a bad water pump will cause engine overheating, it’s essential to note that it doesn’t fail that easily.
#4. Coolant leaks.
Coolant leaks can be internal or external. External leaks happen when the coolant is leaking out of the system, while internal leaks occur when the coolant leaks into other parts of the engine or when something leaks into the coolant.
For instance, oil in coolant and coolant in oil are examples of internal leaks. If oil enters the coolant, it won’t cool the engine as it should until you identify and fix the problem. On the other hand, external leaks will either cause low or no coolant in the radiator.
#5. Damaged or clogged radiator.
The radiator sends cool coolant to the engine and receives hot one from the engine. As the hot coolant enters the radiator, it flows through the radiator fins, which cools the coolant before sending it back to the engine.
If these fins are damaged or clogged, the radiator won’t be able to cool the hot coolant before sending it back to the engine. This will invariably cause the engine to overheat.
#6. Damaged engine coolant fan.
The engine coolant fan blows breeze on the radiator fins to dissipate heat from the hot coolant running through it. The fan is more important when the car is idling. So, if your car only overheats when idling, you have a damaged coolant fan.
#7. Defective temperature sensor.
An electric coolant fan works in harmony with the temp sensor. The sensor sends power to the fan when the engine reaches a certain temperature to help the engine maintain an optimal temperature.
If the temp sensor becomes faulty, it won’t send the electric flow needed to power the fan, causing the engine to overheat.
#8. Air pockets.
It is essential to flush your engine coolant, but what’s more important is ensuring there’s no air pocket in the system. Air pockets can jam up the entire cooling system, and there won’t be any coolant flow.
Hence, it is crucial to follow the instructions in your owner’s booklet when flushing your coolant. However, air can enter the system through a faulty radiator cap or a blown head gasket.
#9. Low engine oil.
Low engine coolant is another cause of engine overheating. Oh yes! Read that again. The engine oil does not only lubricate the internal reciprocating engine parts. It also helps in cooling the engine.
Without the motor oil, there will be too much friction in the engine, which will increase the temperature. If the engine temp gets too high, the engine will overheat. However, it is rare to see overheating due to low engine oil.
#10. Faulty hoses or belts.
You can trace back engine overheating but coolant full to faulty horse or drive belt. The drive belts and hoses are crucial to the charging, air conditioning, and cooling systems.
The drive belt transmits the engine power to the alternator, cooling fan, power steering pump, and compressor. On the other hand, the heater core and radiator hoses convey engine coolant to and from the heater core, radiator, and engine.
If the belt that connects to the water pump and the engine fan is faulty or the radiator hose is bad, it’ll cause the engine to overheat.
7 Signs Your Car Is Overheating
If your car is overheating, you’ll experience one or all of the following signs.
#1. Illuminated Temperature Gauge.
Cars have a temperature gauge on the dashboard. On some vehicles, this gauge is similar to the fuel gauge, with a needle that moves between cold and hot.
If the needle reaches the red part of the gauge, your car is overheating, and you should pull over and turn the engine off immediately. In other vehicles, you’ll see a thermostat indicator light illuminate when the car is overheating.
If everything functions normally, this should be the first indication that your car is overheating.
However, this warning sign only works if your car’s thermostat is working, so don’t rely on it. If you see other signs of overheating but your temperature gauge is not indicating an issue, you should still pull over and turn the engine off.
#2. Burning Smell.
As your engine heats, many of the plastic and rubber components will start to melt, emitting a burning smell. When coolant burns, it smells sweet.
If your heat or air conditioning is on, they will pull the scents directly into the car through the HVAC intake located near the engine. If you notice this smell, open the windows immediately to disperse any potentially harmful fumes.
#3. Thumping or Ticking Sounds From the Engine.
When the thermostat fails and keeps the coolant in the engine too long before letting in new coolant, you’ll hear a thumping noise as the boiling coolant mixes with the cooler liquid.
If the engine has a lubrication problem, you’ll hear a ticking sound as the moving components swell in the heat and bump against each other.
#4. Coolant Under Your Car.
The cooling system is a contained system, so you should never see any coolant under your car. If you do, there’s a leak somewhere in the system.
To determine if the liquid under your vehicle is coolant, check its color and smell , coolant can be yellow, orange, red, green, blue or violet with a sweet odor.
#5. Steam From Underneath the Hood.
If coolant is leaking from the cooling system while the car is running, it will create steam. Coolant is half water, so when it leaks onto overheated engine components or is exposed to overheated air, it will boil and create steam.
#6. Decreased Engine Power.
As the engine overheats, the components within will expand, causing performance issues such as decreased acceleration. If you find yourself needing to use more gas than usual to accelerate, an overheated engine may be the culprit.
#7. Extremely Hot Hood.
A normally functioning car engine runs at about 195-220 degrees Fahrenheit, so your hood will always be hot to the touch when it’s running.
However, you should be able to leave your hand on the hood for at least 10 seconds. If you can’t, your engine is likely overheating.
What should you do if your Car Engine Overheating?
Your car is overheating, and now what? Here are temporary fixes for overheating cars. These will help you prevent further damage to the engine.
- Turn off the air conditioner. This will help relieve the extra strain on the engine.
- Turn on the car heater. Yeah! Turn it on. You’ll reduce the overheating by diverting the heat away from the engine.
- Locate a safe place, pull over, and shut off the vehicle.
- Allow the engine to sit for 30 minutes to cool down.
- Check the radiator fluid and see if it is well-gauged. If it is not, top it as needed.
- Check if there’s any coolant leak and ensure the fan is coming on.
- Drive down to a repair shop while keeping your eye on the dashboard.
How to Diagnose Overheating Engine?
CRITICAL SAFETY WARNING: Car overheating can indicate complete cooling system failure that destroys engines within minutes. Stop driving immediately when overheating occurs to prevent catastrophic engine damage costing thousands.
Quick Tip: Emergency Diagnostic Tools You’ll Need
- Infrared thermometer ($20-$40)
- Basic hand tools for inspection
- Coolant system pressure tester ($40-$80)
- Flashlight for under-hood inspection
- Emergency phone numbers for towing ($150-$300)
Step 1: Immediate Safety Assessment.
When overheating occurs, pull over safely immediately and shut off engine. Never continue driving an overheating engine—damage occurs within minutes and can cost $5,000-$15,000 to repair.
Allow complete cooling (45+ minutes) before any inspection. Check for visible steam, leaks, or unusual smells that indicate immediate danger.
Pro Tip: If you must move the vehicle, turn heater to maximum hot and drive only to the nearest safe location. Heater pulls heat from the engine and may prevent immediate seizure.
Step 2: Check Coolant Levels and System Pressure.
With engine completely cool, check coolant levels in both radiator and overflow tank. Low levels indicate leaks or consumption.
Look for obvious leaks under vehicle—puddles, wet spots, or coolant residue around hoses and connections. Use pressure tester to check system integrity if available.
Step 3: Test Cooling System Operation.
With engine cool, remove radiator cap and start engine briefly while watching for coolant circulation.
No movement indicates water pump failure. Observe cooling fans—they should cycle on when engine reaches operating temperature. SHUT OFF IMMEDIATELY if temperature begins rising during testing.
| Observation | Likely Cause | Action |
|---|---|---|
| Low coolant levels | Leak or consumption | Stop driving, locate leak source |
| No coolant circulation | Failed water pump | Immediate professional repair |
| Fans don’t operate | Electrical/fan failure | Avoid stop-and-go driving |
| System won’t hold pressure | Multiple leaks | Complete cooling system inspection |
Step 4: Assess Engine Damage Risk.
If engine overheated significantly, check for signs of damage: white exhaust smoke (head gasket), milky oil (coolant contamination), or unusual engine noises (bearing damage).
These indicate serious internal damage requiring immediate professional diagnosis before attempting repairs.
Extra Tip: Never remove radiator cap from hot engine—pressurized coolant can reach 250°F and cause severe burns. Wait until engine and radiator are completely cool to touch before any inspection.
Note: Car overheating often indicates the most serious cooling system failures. Do not attempt to drive to repair shop if overheating persists—towing costs $200 but engine replacement costs $8,000+.
How do you fix a car engine that gets overheated?
Once you know the cause, use these proven fixes:
#1. Refill or Replace Coolant.
Use the correct coolant type and remove air pockets afterward.
#2. Repair Coolant Leaks.
Depending on the location, repairs may include:
- New hoses
- New radiator
- Water pump replacement
- Heater core repair
Sealants are short-term emergency fixes only.
#3. Replace the Thermostat.
A simple and inexpensive repair that restores coolant circulation.
#4. Install a New Water Pump.
Essential if flow is weak or the pump is leaking.
#5. Clean or Replace the Radiator.
Flush small blockages; replace severely corroded units.
#6. Fix Cooling Fan Issues.
You may need a new:
- Fan motor
- Relay
- Temperature sensor
- Wiring repair
#7. Replace Damaged Belts.
Any loose or cracked serpentine belt must be replaced immediately.
#8. Repair a Blown Head Gasket.
This complex repair includes resurfacing the head and replacing multiple components.
Prevention Tips
There are several ways to avoid taking your vehicle to a point where its engine overheats and you’re left with serious damage. Below are some of the common ways you can avoid overheating engines:
- Regularly inspect the coolant levels, as it helps avoid engine overheating. Also, make sure you top up the coolant only as much as is needed.
- Arrange proper maintenance of the components in a vehicle’s cooling system. This ensures proper ventilation and coolant flow through the engine assembly, keeping it optimal.
- Avoid towing heavy loads and going excessive off-roading during the hot weather, as it takes a toll on the engine, causing overheating.
- Always make sure you use clean and fresh engine oil and fill at recommended levels only. This helps prevent engine overheating with proper lubrication of the moving engine parts and regulating the temperature by reducing friction.
Other than these, you can also ensure proper checkups and service of the car’s internal parts to keep everything in a perfect working order.
You can also visually inspect the vehicle’s engine for any rust or breakage after heavy driving sessions to stay up to date with the engine’s overall condition.
How much does it cost to fix an overheated car Engine?
The cause of fixing engine overheating could be as low as $20 or as high as $2,000. If the cause of the engine overheating is low coolant, you can get the coolant for $20, and if the reason is a blown head gasket, you may pay up to $2,000 to fix it.
However, since several issues can cause engine overheating, it’s challenging to give the exact repair cost. Aside from the root cause of the overheating, your car’s makes and models play a huge role in determining the actual repair cost.
FAQs.
Q: What should I do if my car starts overheating while driving?
If your car begins to overheat while driving, pull over as soon as it’s safe to do so. Turn off the engine to let it cool down.
Avoid opening the hood immediately, as hot steam could escape and cause burns. Once the car cools, check coolant levels and inspect for visible leaks. If unsure, call for roadside assistance or seek professional help.
Q: Can I drive my car if it’s overheating?
It’s generally unsafe to keep driving an overheating car. Driving with an overheated engine can lead to serious engine damage, potentially requiring costly repairs. Pull over and address the issue immediately instead.
Q: How often should I check my car’s coolant level?
It’s a good idea to check your coolant levels at least once a month, especially before long trips. Regularly monitoring coolant helps ensure the engine stays cool and can prevent unexpected overheating.
Q: How can I tell if my radiator is the cause of the overheating?
Signs of a problematic radiator include frequent overheating, visible leaks, low coolant levels, and rust buildup around the radiator. If you experience any of these signs, you may need a radiator inspection or flush.
Q: Can hot weather cause my car to overheat?
Yes, extremely hot weather can stress the cooling system, especially if you’re driving in stop-and-go traffic or have a heavy load. To reduce the risk, ensure your coolant is topped up and your cooling system is in good condition before driving in hot weather.
Final Words
Car overheating is one of the most severe engine problems you shouldn’t play with. Most times, car overheating causes could be as simple as a coolant leak due to a loose hose or low engine coolant.
If you ignore the root cause for long, it’ll cause catastrophic damages and costly repair costs.
So, always pull over to a safe spot once you notice the temperature gauge is rising on the dashboard. Then, follow the guidelines above on what to do when your engine overheats.