Too Hot to Handle: 12 Reasons Why Your Engine Might be Overheating

An overheating engine is an indicator of several problems in your car. Ignore it and be ready to waste a lot of money and time on repairs.

That’s why it’s extremely important to ensure that you address the issues as soon as possible.

In most cases of overheating, your coolant or thermostat are the culprits. However, it can be an indicator of something serious as well. 

Read on to learn more.

The 12 Most Common Causes of Engines Overheating

There are a lot of reasons why your engine may overheat. Depending on the issue, you can either repair it yourself or visit the mechanic. The following text will look at the 12 most common ones.

1. Bad Radiator Fan

The cooling system for any car operates through the combination of different components. You must have seen a fan over your car’s radiator that turns on and off automatically.

The basic function of the fan is to assist the radiator in keeping the coolant at a low enough temperature for the engine to function properly.

Generally, radiator fans become faulty with time and may not work properly. You’ll notice that your car will be heating up more while idling.

When you drive, the incoming air works just like the fan and takes the heat away.

That doesn’t happen when you’re idling. Check your car’s electric connections, fuses, and temperature sensors to know why your fan doesn’t turn on when needed.

2. Loose or Broken Belts

Whether you drive a new car or a vintage one, you’ll notice an elaborate setup of belts under the hood.

Belts are essential for your vehicle’s normal operations as they transmit power from your engine to the generator, air-conditioning, fans, and other essential systems.

Most vehicle cooling systems operate with electricity. The fans, pumps, and other elements require your belts to work perfectly for reliable operations.

A loose or broken belt may cause friction or stop a certain component from working.

So, it’s important to regularly check the conditions of your belts and change them when required. 

3. Oil Leakage into a Cooling System

Vehicle cooling systems operate on the principle of heat exchange and the liquid needs to have specific thermal properties for ideal operations.

Oil leaking into the cooling system would make the heat transfer inefficient and have another significant effect explained later in this text.

4. Worn Out or Burst Hoses

Belts and hoses act as a lifeline for any car. In many cases, a small fault in your belts and hoses can cause overheating and lead to a major problem in your engine.

That’s why you should always be careful about it.

In the perspective of cooling systems, the most important hoses and pipes are those that transfer the liquid from your engine’s body to the radiator.

Any leakages in them would damage your cooling system and overheat your vehicle.

5. Bad Thermostat

A faulty thermostat is among the most common reasons behind vehicle overheating.

By definition, the function of the thermostat is quite simple. It opens and closes to regulate coolant flow and ensure that the engine stays at the right temperature.

The solution is quite simple. You’ll have to change the thermostat. Generally, it’s located in a plastic housing hear your engine block.

Your manual will tell you the exact location of the thermostat so that you can easily replace it.

6. Water Pump Doesn’t Work Effectively

By now, you must have understood that any vehicle’s cooling system works by moving the coolant around for continuous heat transfer.

The water pump in your car is essential to move the coolant around. Without it, the coolant will be sitting stagnant and overheating your car.

There is, however, one important thing to remember. Water pump faults are extremely rare, so they should be the last thing you check.

Unless you frequently run your car without the coolant, there is a high probability that your water pump is not the reason behind your engine overheating. 

7. Blocked Radiator Airflow

Radiators are responsible for cooling down the liquid inside through air cooling.

Take a closer look at any radiator, you’ll notice a lot of fins on it. These fins increase the exposed surface area to facilitate the cooling process. However, it can be blocked due to debris, dirt particles, and other items.

In many cases, you can sort out the problem of external blockage quite easily with water.

The real problem happens when your radiator gets clogged inside. For that, you’ll have to go through the process of getting your radiator cleaned internally.

It’s a time-consuming process, and you’ll need to visit a mechanic especially if you are a beginner.

8. Leaky Gasket

The cylinders of an internal combustion engine are quite sensitive and the head gasket ensures that they are free from any coolant or oil leakage.

Your engine will overheat if the head gasket stops doing its job.

The coolant will also leak and ultimately damage your engine.

One important thing to note is that the gasket fault is a classic case of the chicken and the egg.

An overheating engine will always damage your gasket and then the engine. Similarly, a damaged gasket will also cause overheating, which will then damage your engine.

The only way to ensure the best performance is to monitor your heat level and keep up with the regular maintenance of your vehicle. 

9. Insufficient Coolant

Another common, but obvious issue is little to no coolant in the radiators. Generally, cars don’t come with any fluid level indicator for your cooling system even though coolants are essential for continuous operations.

If the coolant level gets too low, the heat transfer from the engine won’t be as effective.

Similarly, limited coolant levels will also cause problems in your water pump as it is designed to work in the access of fluid.

All pumps lose their performance and effectiveness if you operate them without the fluid. The ones in the cooling system work just like that and may cause issues in your engine.

The best way to avoid this is to regularly check your coolant levels.

Find the root causes like any leakages or anything else if you notice fluid levels decreasing.

Ensuring that your radiator has enough coolant can save you from a lot of expenses and damages in the future.

10. Low Oil

Everyone knows why oil and other lubricants are important for the vehicle.

The engine oil ensures that the moving components don’t get any wear or tear during use and minimizes the effects of friction.

Anyone from a technical background would know that friction generates excessive amounts of heat.

Without the oil lubricating the contact points of the engine, any vehicle would fail to operate in any condition.

Apart from lubricating the engine, oil has a secondary feature as well.

It carries away all the heat from inside the engines and distributes it to facilitate the cooling system.

Without the right amount of oil in the engine, the heat distribution won’t be as effective and may cause problems for your engine.

Another important thing to note is that it’s very rare to see your engine overheating because of low oil levels.

All cars come with an oil indicator.

You’ll also feel significantly different while driving on low oil, so it is quite unlikely that you’ll go too far without checking the source of the problem.

11. Air Pockets in Your Coolant

It’s already apparent that the coolant plays the most important role in ensuring that your engine doesn’t overheat.

Air caps can form because of the flushing process or if you constantly keep your coolant levels low.

A deteriorated head gasket can also create air pockets in the cooling system, so should get it checked as well.

Bubbling, in the radiator or the expansion reservoir, are some of the most common giveaway signs of air pockets in your cooling system.

Similarly, you might also hear a different sound, but that is quite rare.

12. Issues with the Radiator Cap

Another common, but perhaps easiest to replace the cause of an overheating engine is the radiator cap.

A faulty cap would not allow the car’s cooling system to create enough pressure, which will obviously affect its heat-transfer capabilities.

The most obvious solution for this issue is to simply replace the radiator cap. But make sure that the new one is compatible with your car and has the right pressure rating and other important characteristics.

How To Diagnose an Overheating Engine?

So, you are dealing with an overheating engine. There is a high probability that it’s happening because of the aforementioned reasons. But how do you find out the exact reasons behind it?

The best way to diagnose is to start with the simplest thing.

If you can’t find anything wrong, then you’ll need to visit a mechanic for a deeper diagnosis because the problem is beyond your skills.

Here’s a step-by-step guide to find out the exact reason behind an overheating engine.

  • Check fluid levels: Ensure that all the fluids in your car are at the appropriate level. If your car is overheating because of insufficient coolant, simply top it off. The coolant, oil, and reservoir must be full so you can ensure the best performance of your vehicle.
  • Check for leaks: Pressurize the entire cooling system when the car is cold. You can use a radiator cap tester to put the pressure and check for leaks. In the case of leaks, your cooling system would lose pressure.  
  • Inspect the thermostat: Now that you are sure that the fluid levels are ok and there are no leaks. The next thing is to check the thermostat. If the lower radiator hose remains cold when your car is overheating, your thermostat is the culprit.
  • Check the fans and belts: If you don’t find any issues in the aforementioned steps. You need to check your belts and fan. Stop the overheating car and look under the hood to see the radiator fan. It should be running. Any loose or broken belt will also be visible if you take a closer look.
  • Visit your mechanic: Still can’t find the problem? It means the problem is too advanced for you to handle. Visit your mechanic as soon as possible to get your car inspected.

Why is Your Engine Overheating? The Bottom Line

Take any car. It operates perfectly when a lot of separate systems work collectively to keep everything under normal conditions.

The cooling system of your car ensures that the temperatures don’t exceed beyond the normal operating range. However, they might go bad after a while.

In most cases, the most common reason behind it is insufficient coolant levels, a wrong coolant, a faulty thermostat, or a deteriorated head gasket.

Some issues require simple operations while some will need you to spend some time and money.

However, it’s essential that you address the issue related to overheating engines as soon as possible. 


Dean Alvarez, TireForge Head Author

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