Car Overheating Causes, Effects, Diagnosis, & Solutions

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.

what are 10 common causes of overheating

10 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.

01. 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.

02. 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.

03. 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.

04. 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.

05. 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.

06. 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.

07. 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.

08. 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.

09. 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.

temporary fix for overheating car

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.

Effects of an overheating engine

Engine overheating is the quickest way to damage your engine. Severe engine overheating can cause pistons and cylinders to warp, deform, or bend. This will damage the seals between the engine and the cylinder walls, causing oil to creep into the combustion chamber and burn along with the fuel.

Warped pistons or cylinder walls also cause grinding, whining, knocking, and other terrible noise from the engine. The engine performance will greatly reduce. In a worst-case scenario, the warped pistons will break and cause engine seizure.

How to Diagnose Overheating Engine

Since there are different overheating engine causes, there are also various steps in diagnosing an overheating engine.

Step 1: Inspect the radiator cap and the coolant level

Park the vehicle on a leveled surface and let the engine cool for at least 3o minutes. After that, remove the radiator cap and check the coolant level. The coolant in the radiator should be filled to the brim. If it is not, add more coolant.

Inspect the radiator cap for rust, corrosion, and visible damage. Replace the cap if it is faulty. If you find any other issues during this step, fix them.

Here’s a pro tip; test the vehicle after fixing one issue. If you test it after fixing two or more issues, you won’t know the exact problem.

Step 2: check for leaks

With the radiator filled up, turn on the vehicle and inspect for leaks. If you notice any coolant leak, trace it to where it is coming from. Examine the cooling system components thoroughly. The leak can be coming from more than one place.

Step 3: Check the engine fan

While the engine is running, check if the coolant fan is spinning. On some vehicles, the fan will not rotate until the engine reaches an average operating temperature. Ensure you turn off all the climate controls. Sometimes, leaving the climate controls on will bypass the relay trigger, which is what you are checking.

Wait for the fan to kick in. If the fan doesn’t come up and the engine starts overheating, you either have a broken fan or a faulty relay that controls it.

Let’s narrow down the problem to see if the fan or the relay is damaged. Get two wires and connect the ends to the two pins on the fan. Connect the other ends of the wires to the positive and negative battery terminals. The fan is good if it spins. If it turns, then the relay is bad. If it doesn’t, you have a broken cooling fan.

Step 4: Examine the drive belt

Sometimes, the drive belt can snap off even without you noticing. Check if the belt is still there. If the belt responsible for turning the water pump breaks, the pump cannot circulate coolant to the engine parts. This will cause the engine to overheat more than you can imagine.

If the belt is there, check and ensure it is tight. And if the belt is loose, adjust the tension through the belt adjuster.

Step 5: Burp the cooling system

If air pockets are in the radiator, the only feasible solution is to burp the system. You’ll need the recommended coolant for your vehicle and a spill-free funnel. Connect the spill-free funnel and start the car to let the air bubbles rise and get out of the radiator.

The funnel comes with various attachments. Carefully read the manual that comes with it and follow the instructions.

Having seen diagnosing procedures, let’s see how to fix overheating cars.

How do you fix a car engine that gets overheated?

After diagnosing the vehicle, you will need to do one or more of the following to fix an overheating car engine.

But in reality, can an engine survive overheating? The simple answer is yes. If you notice and fix the engine overheating at the early stage, it won’t do much harm to the car engine.

How do you Avoid unexpected Car overheating?

Prevention is better than cure. And in most cases, it is better to take preventive measures than to fix a problem. Here are my pro tips to prevent a car from overheating.

  • Regularly check the coolant level and top it when needed
  • Periodically check the drive belts, hoses, and cooling fan
  • Cultivate the habit of flushing the radiator periodically
  • Keep your eye on the dashboard while driving
  • Schedule regular maintenance.

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.

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.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

One thought on “Car Overheating Causes, Effects, Diagnosis, & Solutions

Leave a Reply

Your email address will not be published. Required fields are marked *

Recent Posts