A lot of car owners encounter a bizarre situation of having their engine being too hot yet not to the point of overheating, a lot of people are confused by this. This is actually a good thing since it tells something about the car.
It means that something is fundamentally wrong with a car engine that it needs a decent amount of attention before the problem becomes serious. That will be the point of this article, to explain the details of this occurrence.
One might ask, “Why Is My Car Running Hot But Not Overheating?,” here’s a short answer:
A car will typically run hot without necessarily going to the point of overheating because of a faulty cooling system. A single part (example: the radiator, water pump, coolant fan) becomes so defective that the overall cooling system cannot fulfill its job.
8 Reasons why your car is running hot
As a rule of a thumb it is easy to categorize the potential reasons why a car might be running hot without necessarily overheating. Overheating is a serious problem that will almost always cause a permanent damage that will require serious fixing.
A car will run hot without overheating if one of the parts in its cooling system becomes faulty (but will not necessarily damage the whole engine). The 8 most common reasons why this problem occurs are due to the following:
- A faulty/clogged cooling radiator
- Defective water pump
- Insufficient engine coolant
- Old engine coolant
- A failing engine thermostat
- A defective cooling fan
- A failing coolant temperature sensor
- An unreliable oil temperature sensor
Reason 1 – A Faulty/Clogged Cooling Radiator
A coolant radiator is an apparatus embedded in a car’s engine that would allow hot air naturally produced from the hot coolant to be blown away by the fan. It is basically a heat exchange mechanism used by any machine that runs on gas.
A coolant radiator is the final destination of the heat produced by the gas’ combustion to be radiated in the air. It is typically etched at the very front of a car with the design of parallel metal lines where the air can go in the middle.
There are some instances where the coolant radiator cannot cool the fluid that naturally flows in the cooling system. This is probably caused by a radiator that is too corroded/rusty to do its job.
It can also be that the coolant radiator is just clogged by a physical material (such as a cloth) or accumulated dust that would not allow the heat to naturally radiate on the surroundings. This can certainly result in an engine that is too hot but is not necessarily overheating.
The heat that is naturally produced by the combustion will remain in the car since most of it does not get transferred outside the car. Over time it will result in an engine that is just generally hot when running (since the combustion only occurs when the engine is running).
Reason 2 – Defective Water Pump
A car’s water pump is exactly what it sounds like, it is a tool designed to pump the cooled fluid from the radiator to the engine and back to the engine’s entire cooling system. It is the one that circulates the car’s cooling fluid.
As you can imagine it can be disastrous if the water pump is defective, it means that the cooling fluid would not properly circumvent throughout the engine making it pretty hot when running.
The extent of the water pump’s defect will determine the size of the problem, a car owner is actually lucky if it only results in an engine that is slightly hotter than usual. In some instances the headache will be more than that.
Some defective water pumps will only be ineffective in their function of transferring the fluid but can still get the job done, this will result in an engine that is only slightly hotter than usual (since the cooling liquid is not properly circulated).
In some instances however the defective water pump can outright not transfer the fluid at all. letting the engine run without any cooling liquid. This will definitely cause overheating that will melt some parts of the engine and cause some car repair expenses.
Reason 3 – Insufficient Engine Coolant
A car’s engine coolant is a special liquid that absorbs excess heat generated from the natural combustion within the engine. It is a mixture of antifreeze and water that not only protects the car from excess heat, but also to excess cold.
There are many brands that one can go with when it comes to a car’s engine coolant, but it’s job is to primarily transfer the heat onto itself while being circulated by the water pump. A good engine coolant can ensure an optimal performance to the car.
Expert Tip: It is important to take note that the regular water reservoir in an engine is separated from the engine coolant, the coolant is a special type of liquid that needs to be bought from a car store. The brand of the coolant matters as well.
When there is an insufficient amount of engine coolant currently present in a car engine, it will result in a substandard cooling system that will make the engine run hot. This is probably the most probable reason why a car will run hot without overheating.
It could be that the water coolant has received minimum maintenance and needs some additional attention, this is of course easy to fix since one could just add a compatible engine coolant and the problem is fixed. Looking at the engine coolant level is a good idea since this might be the issue.
Reason 4 – Old Engine Coolant
Another reason why a car might run hot without necessarily overheating is having an engine coolant that is too old (but not inefficient). A coolant would naturally lose its ability to transfer heat over the course of time.
Professionals in the car maintenance industry recommend changing the water coolant every two years or so since this will be the time that its properties cannot do the job anymore. The antifreeze and anti-rust will take a toll as well.
A coolant that has been used time and time again would be ineffective anymore and will need a replacement/fixing. This could be avoided by having a good maintenance routine of checking the coolant’s effectiveness.
There are also situations where the liquid coolant will be considered old even without the two years mark, which is especially the case in substandard engines that are hotter than usual. This will cause the engine to be hotter than usual.
If this is the only problem in your car engine then it might explain why it is not overheating, this means that the other parts of the cooling system are working properly. Just changing the liquid coolant should solve the problem in these instances.
Reason 5 – A Failing Engine Thermostat
A coolant thermostat is an apparatus located between the radiator and the engine that dictates whether the liquid coolant is allowed to circulate within the cooling system. It is necessary that this is working properly.
The liquid coolant is circulating indefinitely while the engine is running to minimize the heat from combustion, however, once the engine is turned off there needs to be a way for the coolant circulation to stop. This is where the engine thermostat comes in.
It blocks the liquid coolant and allows the flow to stop whenever the engine is not running, however, when this thermostat becomes defective it will cause some heating problems. It has something to do with the coolant flow
A failing engine thermostat might open up too late or too early than when it is supposed to let up. this will cause the car’s engine to be overall hotter since there is no coolant circulation. This might be the cause of the problem.
When a car engine with a failing thermostat is active, the coolant liquid might be late in its natural circulation and will cause the engine to be naturally hotter than usual (without overheating). Checking the thermostat condition every now and then is good practice.
Reason 6 – A Defective Cooling Fan
A cooling fan is an actual fan located in the engine that starts when the combustion is active, it helps circulate the air flow and prevents heat from accumulating in the internal apparatus. This helps in cooling the car down.
It blows away excess heat that is resulted from every other part of the cooling system through the radiator, it operates just like how any other fan would. It is located between the engine and the radiator which lowers the overall temperature.
The backside of the fan gathers heat naturally and transfers it outside of the car, removing excess heat that would cause some problem in an engine. This would become inactive when the engine is turned off.
Expert Tip: If you’ve noticed that a car engine remains too hot in slow traffic when the car is not even running at decent speeds, it is likely because of a defective cooling fan that cannot even maintain minimal heat. It is an important part of the car’s cooling system.
If the cooling fan spins weakly there might not be enough force to generate the attraction of hotair, this would make the engine generally hot when active. It may also not cause overheating since all the other parts should be working properly independent of the cooling fan.
Reason 7 – An Inaccurate Coolant Temperature Sensor
The coolant temperature sensor measures the overall temperature of the engine and gives an idea of how hot/cold the coolant system has become when running. Some cars have more than one temperature sensor measuring different parts of the car and not just the engine.
The most important part though is the one that measures the cooling system, this is because the majority of the problem comes from a defective part in the cooling system that needs some repair.
There are certainly many cases where the coolant temperature sensor is not accurately displaying the right numbers for the owner to see. this can lead to the illusion that the car is hotter than what it actually is.
If you have noticed that the temperature report from the coolant sensor is going off the charts and there’s really nothing wrong with the engine, it is worth figuring out if it is the problem. There have been cases like this.
Maybe it is not that the engine is running hotter than normal, it may be that the report is just giving inaccurate results of what’s really going on. This is actually the best case scenario since it means that nothing serious is happening and you just have to fix the coolant temperature sensor.
Reason 8 – An Unreliable Oil Temperature Sensor
An oil temperature sensor measures the overall temperature the engine oil has acquired in a period of time. The engine oil is responsible for lubricating the entire cooling system but also helps in regulating temperature.
This is a separate measurement from the coolant temperature sensor which only involves the engine oil. however, it can also be defective and give false red warnings that are not accurate to the oil’s actual temperature.
This issue is similar to the previous one except it involves the temperature of the engine oil and not the coolant, both temperatures should be around the same level when the engine is active. If it is not. then it might be a false warning.
If you can identify that the oil temperature sensor is way hotter than the coolant temperature sensor then this could be another issue of inaccurate results. Again, this is one of the best case scenarios since you just have to fix the oil temperature sensor and nothing serious is going on.
How To Fix A Car Running Hot
After identifying these issues there are many remedies an individual can deliver depending on the situation. If you are in the middle of nowhere and are looking for a quick fix here are the things you should do.
- Turn off the air conditioner since it puts additional pressure to the engine resulting in more heat generated to the car’s environment.
- Turn on the heater since it helps in dissipating the excess heat that is around the vehicle. It will help cool the engine down although it will be hot for the car’s passengers.
- Shift your car into neutral or park and activate your engine. This will cause the cooling fan and water pump to work much faster resulting in more radiated heat from the internal to the external of the engine.
- Find a safe place to park and pull up the hood exposing the engine to the outside air. This will help with air circulation and radiates excess heat throughout the surroundings (be careful with steams though since it may come out when opening the hood).
- Don’t remove the radiator cap when the engine is active since it may cause burns.
The best solution to fixing a car that is always running hot is to obviously identify the defective parts of the cooling system and fixing them. If it is on an emergency and you need a quick fix then the tips above will apply.
How do you know if your thermostat is bad in your car?
Here are the signs to look for when trying to assess if the thermostat on any given car is faulty:
- The thermostat are giving really dynamic results.
- The thermostat reading too high when the engine is barely active.
- There are visible leakage accumulating in the surface of the thermostat.
- There are too much rust on the inside of the thermostat and the corrosion process is already happening.
- Different kinds of deposits (sludge and dust) accumulates on the inside of the thermostat interfering with its regular function.
Assessing the condition of the thermostat can either be a subtle process or a straightforward one. depending on the size of the problem. Consulting with a car expert can give you the most accurate diagnosis.
What are signs of a bad head gasket?
Diagnosing a bad head gasket is easier than assessing a bad thermostat, there are many signs to look for when identifying a bad head gasket. These are the signs that may appear:
- A white smoke is being expelled from the tailpipe.
- There are consistent bubbling in the radiator and coolant storage.
- Coolant loss without any visible leaks.
- Leaks will have a milky white coloration with them.
- The engine always overheats for an unexplained reason.
The head gasket is an important part in keeping a car’s cooling system and check, having a defective one can definitely be the temperature issue waiting to occur. It absorbs stress from the cylinder block and the cylinder head preventing any engine or coolant leaks.
A car can run hot without necessarily overheating due to certain parts of the cooling system that is not fulfilling their function, usually there is only one to two of them.
The problem can either be on the radiator. water pump, engine coolant, engine thermostat, cooling fan. coolant temperature sensor, or the oil temperature sensor. It is important take a look on these parts when fixing this problem.
Feel free to comment below if you have any questions regarding this topic. Also, you can share your thoughts and experiences so we can help others that are experiencing this same issue.
Remember, a car that is running hot without overheating will only have one or two defective part in its cooling system. This makes the car hotter than usual but will still be usable for a period of time and not overheat.