Car running hot but not overheating is extremely frustrating. It’s even more frustrating when you’re doing everything right to keep your cool, and the car is running hotter anyway.
We’ve all been there, done that. It seems like an impossible situation with no solution or end in sight. So then what? How can you cool it down? What are your options? Or do you just give up and watch as the engine overheats, boils over, and dies a slow, agonizing death?
If you are one of those drivers who are dealing with the issue of a hot engine, this article is for you.
Car running hot but not overheating is just a symptom. In actuality, something has terribly gone wrong with your car when the temperature gauge is showing a high-temperature reading.
Following are the main reasons behind car running hot but not overheating:
- Bad Coolant Temperature Sensor
- Faulty Head Gasket
- Low Coolant or No Coolant
- Faulty Water Pump
- Broken Temperature Gauge
- Faulty Thermostat
- Defective Cooling Fan
- Bad Radiator Cap
In this article, I’ll tell you the reasons for a car overheating in great detail!
Table of Contents
Why is Heat Produced in an Internal Combustion Engine?
Your car temperature gauge is showing a hot sign, it might be due to a defect in the cooling system. But where does this heat come from?
Most car owners believe that heat is produced in an internal combustion engine because the gasoline is set on fire. To understand why heat is produced in an internal combustion engine, you have to know how it works. First, let’s look at all of the parts that make up an engine.
The car engine has four main parts. First, the intake manifold feeds air and gasoline into each cylinder. Next, a spark plug ignites the mixture in the combustion chamber. Then, the piston moves up and down within the cylinder head.
Finally, an exhaust manifold releases all of the remaining gas once it has turned into carbon dioxide.
The next thing you have to know about how car engines work is that they are sealed off from each other. Each time a cylinder fires, it creates pressure that pushes the piston down.
This then causes one end of the crankshaft (a part that rotates inside of the engine) to turn, which causes it to rotate around and around. While this happens, pistons in other cylinders rise, preparing for their next “stroke.”
When the spark plug fires, it creates a spark that ignites the gasoline mixture. This causes the gases to heat up, creating pressure. The pressure is used to push down on the piston, moving it within the cylinder. Some of this energy is transferred to your car’s wheels, where it can make them spin.
Finally, you have to know that four-stroke engines are designed to complete four steps to work. These include intake, compression, power, and exhaust.
The first step is called the intake stage. Right before this happens, your car’s piston is at the very top of its travel, where it gets ready to begin its descent down into the cylinder. At this point, the intake valve opens, allowing gases to come into the engine.
The next step is called compression. When your piston begins to travel back up towards the top of its path, it compresses the gas it has just brought in from the outside. Air pressure can get very high at this point. This causes more fuel to get ready for its next step.
As the piston continues to move up, it compresses the air and gasoline inside it. This is one reason why an engine can get so hot from all of the compression during this stage.
Another reason for heat at this point is that combustion takes place due to extreme pressure and heat throughout the entire process.
Next, the third stroke called power happens. The piston continues its upward motion and pushes down on a pin that’s connected to the crankshaft. This causes the crankshaft to rotate one full turn as it spins around and around inside of your engine.
Finally, you have to know that there’s one more thing that happens in an engine. This is called the exhaust stroke. When your piston reaches the top of its path, it begins to travel downward again until it reaches the bottom.
At this point, another valve opens up, allowing all of the remaining gases to be pushed out until there is barely any left inside of your engine’s cylinder.
After these four stages are over, the entire cycle begins again with the process of intake valve opening that allows fresh air and fuel to come into your engine.
Reasons For Car Running Hot But Not Overheating
If your car is overheating, there has been a malfunction somewhere in the cooling system.
Let us see these reasons in detail:
1. Bad Coolant Temperature Sensor
The coolant temperature sensor is one of the most important components of a car’s cooling system. It is responsible for displaying temperature readings on the car temperature gauge.
A faulty coolant temperature sensor may prevent the ECU from taking necessary actions to prevent overheating, or temperature gauges can indicate a false high temperature because it prevents coolant circulation. In most cars, if the engine reaches about 240 degrees Fahrenheit (115 degrees Celsius), the cooling fan will start. If this safety mechanism fails, the engine may overheat.
2. Faulty Head Gasket
If the head gasket on your car fails, all four of the coolant (water+coolant mixture) would suddenly start leaking without any indication and all of them would concurrently reach the radiator at same time.
Since there is no way for gases to escape from cylinders, the mixture of water and coolant would be thrown out from the overflow reservoir tank via a hose/pipe. This is when you notice steam billowing from your car radiator.
This is how a cracked head gasket would lead to the overheating of your engine.
3. Low Coolant or No Coolant
The temperature gauge of your car might be showing high-temperature reading due to a low coolant level. If you don’t have sufficient engine coolant in your coolant reservoir, your engine may overheat because it prevents the circulation of hot coolant.
Check the reservoir for low levels and top up if needed, ensure that you have enough coolant at all times. You might have to do a radiator flush to drain the old coolant. It’s essential to use the right type of new coolant for the climate you live in.
4. Faulty Water Pump
Your temperature gauge will show overheating sign if you have a weak or faulty water pump. A faulty water pump can significantly reduce your car’s efficiency and increase engine temperature.
Water pumps may be defective due to a plugged passage that restricts circulating fluid or too much play between the impeller and housing.
5. Broken Temperature Gauge
If your car’s temperature gauge is broken, you will get a false engine temperature reading. A faulty temperature gauge will not let you know when the engine reaches dangerous levels of heat – this is because it prevents the circulation of coolant.
However, you can check for proper functioning by touching the radiator hoses and seeing whether they are hot or not.
6. Faulty Thermostat
The thermostat is one of the most critical components of the cooling system o your car. The thermostat regulates coolant movement through your car’s engine. A defective thermostat will allow the coolant to circulate too quickly and can lead to severe engine overheating.
7. Defective Cooling Fan
A radiator fan aids your car’s cooling system in keeping the engine cool.
A defective cooling fan may not spin, or the blades may be stuck, which increases resistance and reduces airflow across the radiator, preventing proper cooling – this is because it prevents coolant circulation.
8. Bad Radiator Cap
The radiator cooling cap regulates the coolant pressure, which can overflow if it’s not working properly – this is because too much pressure may cause boiling and even an explosion.
How To Fix Car Running Hot But Not Overheating?
We’re going to cover your options right here. We’ll also offer a few helpful tips on what to do if the problem of the car running hot but not overheating persists after you’ve tried everything.
You have several options here actually, and they all depend on the severity of the overheating situation. Remember that your car can still run hot even when it is not yet in the overheating range.
A) You can let it run hot and just shut down all the electrical accessories until it cools down. The problem with this option is that you’ll be stuck without power. If you need to change a flat tire, for example, you won’t be able to use your power windows or door locks…and then you’ll be forced to use one of the other options.
B) You can open up all your doors and remove everything from the passenger compartment (floor mats, glove box, center console…all contents). This will allow hot air to escape and cool air to come in. This is my favorite option and usually solves most overheating problems. The heat cycle will usually take the rest, and your car should be fine.
C) You can leave all the doors closed with the windows down about an inch…just enough for a breeze to come in and cool you off. This is another option and works just as well as those above.
D) You can use any quick and easy, low-cost radiator cooling solutions to help cool it down.
E) You can just wait until your car cools itself down. This is my least favorite option since you’ll need a new engine or some other major repair by then…and that’s expensive!
Car running hot but not overheating can have serious repercussions. You need to be careful about this problem.
If you don’t do anything about the fact that your engine is overheating, it will cause damage. The best-case scenario includes warped head gaskets, but before it gets that bad, the car will probably just overheat. Beyond that point, you’re playing with fire – literally.
Heat is high up on the list of things that can cause a fire in your engine, especially when there’s something like antifreeze involved. When your car overheats, and you try to keep driving, there’s a good chance your car will catch fire. If it doesn’t catch fire, the damage caused could cause even more problems down the line and lead to other components catching on fire as well.
Not only is it dangerous for others, but the heat from your car’s engine could cause injuries if you touch the hood, grille, or exterior metal of your get-away vehicle. If you can get away with it, turn off your air conditioner (if you have one) and roll down the windows instead to release some of that heat.
If you have a fluctuating temperature gauge, you should not take it lightly. Take your car immediately to a mechanic and fix the overheating problem!
Frequently Asked Questions
Should I drive my car when it is overheating?
No, you should avoid driving your car if the engine temperature gauge shows a red sign. It usually means that something has terribly gone wrong with your car or its cooling system. Hence, to prevent further damage to the engine, you must not drive a car running hot but not overheating.
What to do when the engine temperature is normal, but the temperature gauge is showing hot?
It occurs when you have a broken temperature gauge. High-temperature gauge reading does not necessarily mean that your car has an overheating problem. A faulty temperature gauge will show a false high reading of the engine’s temperature.
You must check for other symptoms of the car running hot but not overheating. If you do not see any other symptoms, then get your temperature gauge or temperature sensor replaced. It might have gone bad.
What to do when the engine is hot, but the temperature gauge is not moving?
You can try fixes for a car running hot but not overheating. The majority of times, the car is overheating due to a problem in the cooling system. Check for the problems like a coolant leak, low coolant, faulty water pump, and defective cooling fans.
How to fix a broken car temperature gauge?
If you are getting false reading for engine temperature, it might be due to two reasons. You might have a faulty temperature gauge or a failed temperature sensor. A failed temperature sensor needs to be replaced. However, a faulty temperature gauge can be repaired as well.
A car temperature gauge’s sensing element or electrical wiring can go bad. Change the faulty component of the temperature gauge, this is the only way to fix it.
What are the major symptoms of the car running hot but not overheating?
Following are the major symptoms of a car running hot but not overheating:
- Fluctuating temperature gauge
- Head gasket failure
- High-temperature gauge reading
- Check engine light