Your car may experience little hiccups sometimes and need a professional checkup and some extra attention to get back on the track. You don’t need to panic if your car is acting strangely suddenly, even if it is a new car. Cars can have some common problems, and some precautions will ensure you to prevent these unexpected glitches in the future. Usually, the old car may have experienced a lot of overheating issues, especially during summer time. But with a proper knowledge of the cooling system and symptoms might help you to sustain this issue. In MotorSparePart, we always try to identify and discuss various car related issues, so let's find out what cause's car overheating and what steps you could take to prevent it. 

Here are details of what to do if you have an overheating problem, what might cause a car to overheat and what precaution should be taken to resolve this matter.


How does a car cooling system works

Car engine basically an internal combustion engine where power is generated through expansion of high-temperature and high-pressure gases. A lot of hits generated due to the combustion gas and the fraction of mechanical pasts for sustained operation. These excess hits should be removed from the engine and kept at operating temperature.


Let’s see the parts involved in cooling the engine:

The main components for cooling the engine are-

1. Water pump

The water pump is the heart of the cooling system which pumps the coolant. It consists of an Impeller, a Pulley flange, and an O-ring. The engine drive belt drives the impeller through a pulley.


2. Radiator

The radiator is a heat exchanger used to transfer the excess heat developed by the engine to the atmosphere. The radiator has an inlet port, outlet port, drain plug and a radiator pressure cap. The radiator pressure cap plays a vital role in the cooling system.

3. Thermostat

The Thermostat is a valve which regulates the flow of the coolant and helps to maintain the proper operating temperature for the engine. The thermostat consists of a frame, charge cylinder, main valve, main spring, bypass valve and secondary spring.

4. Coolant Temperature Sensor (CTS)

The coolant temperature sensor is used to monitor the engine temperature. The ECU will use this data to manage fuel injection and ignition time. Some engines have more than one coolant temperature sensor. The data is also used to control the radiator fan and to update the temperature gauge on the driver console. The coolant temperature sensor consists of a sensing probe and electrical connector. Most coolant temperature sensors are negative temperature coefficient type which means as the temperature increases the resistance will decrease. The CTS can be a two-pin type or a three-pin type depending on the make of the wheel. These are the main parts involved in an engine cooling system.

5. Coolant (Antifreeze + Water)

A coolant is a fluid known as Antifreeze, a bright yellow or green liquid that mixes with water. This liquid is mainly used in the coolant expansion tank to keep the radiator active from freezing or overheating. It is a mixer of ethylene or propylene glycol and water, usually in a 50-50 ratio.


Let’s see how these parts work together:

Pistons are contained inside the engine block in which of them will function. Above the engine block comes the head Gasket which provides sealing between the engine block and engine head. It avoids compression leaks and oil or coolant leaks into the cylinders. Above that come the engine head. The engine has a safe passage through which the coolant can flow without entering into the cylinder or mixing up with the oil. This passage is known as “Water Jacket”.


The water pump pumps the coolant throughout the system with the help of the radial impeller. It is driven by the engine itself using a serpentine belt. The serpentine belt also drives the power steering pump alternator AC compressor. 


Here are the parts connected each other- Car Cooling System

• The thermostat bypass hose

• The thermostat inside the thermostat housing

• The radiator and the radiator fan

• The lower radiator hose

• Water pump outlet hose

• The coolant expansion tank

• The expansion bleed hose

• Overflow hose

The thermostat is actually a valve which regulates the flow of the coolant. It will always be covered in the coolant so the temperature can be sensed. When the engine is cold, the bypass valve stays open. So the coolant bypasses the radiator and recirculates through the engine. This helps the engine to heat up to operating temperature quickly. Eventually, the coolant temperature increases by absorbing the heat from the engine. Once the coolant starts to reach a higher temperature which is usually between 160 & 210 Fahrenheit, the bypass valve will start to close, and the main valve will start to open.

This allows the cold coolant from radiator flow to the engine side and the hot coolant from engine side to coolant side. In most cars, the coolant temperature sensor is located near the thermostat housing. It will turn on the radiator fan if the coolant to the radiator side is at a higher temperature. Now the hot coolant in the radiator will release its heat to the atmosphere with the help of the fan. At the same time, the cold coolant received from the radiator will start to absorb the heat from the engine for the next cycle. Heating liquids inside a closed system always build up the pressure.

So how to maintain the pressure? Here comes the role of the radiator pressure cap. It consists of a spring loaded valve mechanism which will respond to higher pressure. Reaching a pressure above 15psi will push the pressure cap valve, and the coolant flows to the expansion tank until the pressure goes down to operation level. And when the system cools down, the vacuum inside the system sucks back the coolant from the expansion tank. In case if there is too much pressure build up in the system due to trapped air or other failures, the coolant in the expansion tank will be pushed out through the overflow hose.


What's the Heater System does in a car?

The car heater system is a part of the engine cooling system. The heater system comprises of the heater core inlet and outlet hoses, a heater control valve which is optional and cannot be found in all vehicles. The heater core acts as a radiator dissipating heat from the hot coolant to the vehicle interior using a blower.

Why/What causes an Car Engine Overheat?

1. Leakage of Antifreeze or Coolant

Leakage of Antifreeze or Coolant is a very common cause of car gets overheating. You may find a crack in the coolant reservoir since it the main system that keeps the car engine cool. In that case, you might be able to see coolant pooling under your vehicle when sits for a long time. There are only three common reasons for coolant leaks, although each type of leakage has several potentials.

Faulty Radiator Cap


Faulty Radiator Cap

Every time the coolant heats up, you may experience loss of coolant from the overflow tube if you have a broken or weak radiator cap. The Radiator is a pressurized system, so if there is a loss of pressure from the cap not fitting properly or if the cap is not the correct one, the pressure will be lost, and a leak might occur. With a Pressure Test of the radiator test, this can be identified. Refer to your car manual for the correct cap and pressure. Tutorial for testing a radiator here


Internal Leakage

An internal leak could be noticeable when your coolant liquid level does not stay constant, and you need to refill the tank regularly. An internal leak could be caused by a leak in the head or block or perhaps a leaky head gasket which lets the coolant leakage its system.

External Leakage

An external leak can be most easily diagnosed. A split or broken hose or a hole in the radiator is two good examples of external leakage. Leaks in the water pump, heater core, or engine freeze plugs can also allow coolant to discharge. These are also easy to detect by a visual inspection.

2. Radiator/Cooling Hose Busted or Worn out

Radiator Hose Worn Out

The cooling or heater system hoses carry coolant liquids through the radiator and back through the engine to keep it operating at an optimal temperature. Several rubber hoses make up the plumbing to connect the components of the cooling system. If a cooling or radiator system hose wore out or busted, the engine will not get the proper amount of coolant and will overheat, possibly causing severe damage to the engine. Most commonly check the clamps on the hoses.

If the hoses predominantly at the manufacturers and the hoses are about seven to ten years, you probably ought to replace them with screw type clamps. You can squeeze the rubber hoses, and if you hear the crunch and crack noise, that might be rust and lime deposits some minerals that have built up inside, and you are breaking it off. That’s a good telltale sign to replace the hoses. Because it is blocking the coolant getting to the engine to cool it down. Sometimes you might find rust and grime in the coolant which comes from the radiator or tubes. Pressure check is highly recommended and refills the coolant with a proper mixture of coolant.


3. Damaged Water Pump

The water pump is the primary component responsible for maintaining the flow of coolant from the radiator throughout the engine. When it works correctly, your vehicle will maintain a consistent operating temperature. Typically, most of the time if you have damaged Water Pump, it will be leaking. There is a seal in front of the water pump, and when it goes bad, it will leak coolant out of the water pump. You may hear a noise, where it's like a bearing noise like a loud whining noise in the engine compartment and that, would be time to look at the water pump to see if the bearing is going bad in the water pump.

You may rarely see it where the water pump bleeds come loose from the pump itself and pump will still be turning everything looks fine, but they don’t pump any water. These are a little bit difficult to diagnose usually you should get help from a professional to check how much water is pumped through the engine to see if the water pump is pumping water or how much water is pumping. If you get the overheating problems on the highways, there is a possibility that the water pump is not working correctly and needs to be replaced. It may cost from $100-$800 dollars.


4. Radiator Breakdown

The radiator is an integral part of a car's cooling system. It cools the coolant, which is a substance used to absorb the heat from the engine, using water and cool air from outside the system. Without this critical component, the engine would eventually overheat, and the Pistons would break, causing permanent damage. Therefore, it is imperative that car owner’s deal with broken radiators before that happens. It’s hard to diagnose radiator damages, but there are few signs and signals of failure.


Signs of Breakdown

In general, leaks and overheating are the most obvious signs of failure. However, simple leaking hoses and loose parts can cause both problems, and it is important to pay attention to other indicators of failure.

· Leaking

The first most visible sign of a radiator problem is when the car is not in use to see a puddle of liquid forming beneath the engine. Leaky radiators require immediate attention, as they can cause severe damage. The fluid that leaks out is toxic to humans and animals. Radiator coolant fluid looks green or red in color and is slimy in texture. Other types of fluids under the vehicle are signs of different problems.

· Overheating

As though the radiator's primary job is to keep the engine cool as it runs, but minor overheating is a major sign that something is wrong and need to be checked. Leaking could be simple for overheating problem, but overheating is sometimes a sign of bigger problems. So it is important to investigate the problem as soon as recognized.

· Drop in Pressure

If the radiator has a lot of corrosion, it produces lower pressure levels than normal. Radiators should produce 10 PSI to 12 PSI. If this level is low, then you have to realize that a problem might exist. Car owners can use pressure gauges to determine the pressure. These devices fit on top of the radiator cap, and gauge pressure as the engine runs.

· Low Coolant Levels

If the coolant levels are low, the radiator probably has a leak. Coolant naturally depletes over time, but sudden drops in the coolant level are not normal. Car owners should check hoses and connections to make sure everything is tight. If those parts look like they are in order, the system could have a hole somewhere.

· Rust

Corrosion on or around the radiator indicates a leak or rust. As the liquid leaks, it heats up and causes the metal to rust.

Tips to Avoid Radiator Issues

· Flush the coolant every 20000 miles. This will prevent rust and also minimize mineral deposit buildup.

· Check your hoses and clamps on a regular basis. A crack, loose clamp, a small hole or other problems should be addressed immediately.

· Get on a regular coolant check schedule. Every week or so, ensure that your coolant level is full. If necessary, add extra coolant to the overflow tank. And keep tabs on your engine temperature gauge while driving.

4. Faulty Radiator Fan

All the latest model vehicle now uses electric motors radiator cooling fans to keep the engine cool. The radiator is mounted at the front of your vehicle behind the grille where it is exposed to airflow when your vehicle is at speed. And a cooling fan attached to the back of the radiator to keep a cooler temperature in the radiator. However, when your car is moving slowly or stopped, there is little or no ram air through the grille, so the constant airflow is supplied by a cooling fan. There are some common problems with radiator fans, and if your vehicle has one of them, fixing it is relatively quick and cheap to administer.

You could be easy fooled into believing that the fan isn’t working, so carry out a visual check to be certain. Do this by lifting the hood and listening carefully. The fan in newer engines might be mute, so you don’t hear them when you're sitting inside your vehicle.

Radiator Fan

· Fuse

The first thing to check is the fuse whenever something electrical doesn’t work. Your vehicle could be different built-in designs. So If you don’t know where the fuses are on your vehicle, read your owner’s manual to see which fuse controls the cooling system. Normally it is under the dashboard. You have to make sure that the fuse for the radiator fan is intact. If it is not, replace it directly, and this should take care of the problem.

· Fan Wires

If you find the engine is heating but the fan isn’t kicking in, check the fan wires or do it manually. You can start by unplugging the cables. There will be two wires of positive and negative feed. It should be putting out around 12 volts. Use a voltmeter to check that there is current present. You need to check both the wires and the fan relay and see If there is no current present, your fan wiring need to be replaced.


The fan relay will be under the hood. Your fan could be faulty and need to be replaced If there is voltage running from the relay to the fan. If you require changing the fan, make sure that the replacement has the right CFM rating for your vehicle.


· Temperature Sensor

Basically, by reading the cooling system temperature, the temperature sensor determines when the radiator fan comes on. If your temperature sensor isn’t working, your fan won’t come on because it won’t know that the temperature is hot enough to require activation, which can frequently lead to overheating.

Generally, the temperature sensor is positioned in the car thermostat cover. To check it, you have to disconnect the wires from the sensor and touch them together. If this starts the fan, the sensor is faulty and will need to be replaced. Read the manual to make sure exactly where the temperature sensor is on your car.

· Coolant Level

Check the coolant level in your engine. The simplest way to do this is to look at the tank in the engine. It will be marked with maximum and minimum levels. And always try to make sure that the coolant level is up near the maximum level to avoid possible overheating.

· Fan Clutch

The fan clutch is the assembly to hold the radiator fan to the engine and makes it turn. If it burns out or fails, you’ll need to replace it. Springs within the fan clutch can wear out or corrode over the years. If everything else seems to be fine, the fan clutch is the most likely cause of radiator fan failure.


5. Broken Serpentine Belt

A belt which is used to drive multiple peripheral devices such as a power steering pump, water pump, air conditioning compressor, air pump, alternator, etc. is called Serpentine belt. It is also known as drive belt or multi-vee or poly-v. But there are a few difference between this two. Few vehicles have single drive belt while others have multiple. The serpentine belt is a complicated part of drive belt system. It continues to operate when the engine is on until the vehicle is shut off. Without the operating driving belt, the car won’t be functioning at all. Typically, a drive belt lasts up to 40000 to 50000 miles or five years before it needs to be replaced. But check the owner’s manual for exact service interval. Over time, the driving belt could fail and need to be replaced. If you find any unusual symptoms, it’s better to check it out. There are few signs to know when the drive belt needs to be replaced. Replacing the serpentine belt may cost from $75 to $250, depending on the type of the vehicle.

Serpentine Belt

· Screeching/ Chirping Noise

If your engine belt makes a screeching or sequel noise, it might be the noise of rubber belt slipping on the metal pulley. It is just like spinning your tires on the road. The serpentine belt might be slipping due to improper tension or simply gotten old, and the surface has become cracked, glazed or brittle. Diagnose the issue and contact a professional mechanic to have them replaced.

· Engine Overheat

Since the water pump works by the power provided by the serpentine belt and cools the engine, failing belt can cause your engine to overheat. More you left the overheating problem in your vehicle, the more damage you will lead the vehicle into.

· Disable Power Steering and AC

Your car will break down if the drive belt ultimately fails and breaks. Consequently a loss of power steering, the air conditioning will not work at all. Besides, the engine will no longer be able to cool as it should be.

· Cracks and Wear on Belt

Visual checking on the serpentine belt can show that if there is any cracks, missing chunks or other signs of wear. Once you see any of these, it is better to get the belt replaced.

· Engine Light Illumination

Some vehicles show the engine lights to warn you that there is something wrong with the systems and sometimes this may be an indication of failure serpentine belt.

6. Jammed Thermostat

A thermostat regulates the temperature by controlling coolant flow in the engine. Coolant cools the engine, and the thermostat maintains the temperature by letting the coolant in and close when need it. The coolant is blocked until the engine warms up. Most rarely, if the thermostat is jammed or not working properly, the engine will be overheated. The thermostat is installed in your car by the manufacturer that opens at the car’s operating temperature which is usually either 1800 or 212o Fahrenheit. If your thermostat is jammed or nor working, there are several indicators to test and find out the problem.


Test 1: Open the hood and remove the radiator cap. Start the engine. Observe coolant action. It should not be moving because when the engine is cold; the thermostat should be closed, thus bypassing the radiator.

Test 2: Open the hood and remove the radiator cap. Start the engine and observe coolant action. It should be swirling vigorously because when the engine is warm, the thermostat is in the open position. This allows the coolant to flow through the radiator causing dynamic movement.

Test 3: Start the engine. Get the time how long it takes the engine to warm up enough to produce heat when the heater is turned on. It is a sign that the thermostat is stuck open, allowing all the coolant to flow all the time If it takes more than five minutes. This causes a long time to warm the engine up.


If you find out any of the tests positive and determine that the thermostat is faulty, you should replace the thermostat quickly to stop overheating the vehicle.

6. Not Concentrated Coolant

A concentrated coolant is a fluid known as Antifreeze, a mixer of ethylene or propylene glycol and water, usually in a 50-50 ratio. There is a coolant tank in every vehicle to keeps the engine cool from getting overheated. Usually, you can check from the outside of the reservoir, and there should be a mark to show the maximum and minimum fluid levels. If there is a change in the levels, it could be an indication of leakage or failure in the system somewhere. You can also check from the coolant by removing the cap from the radiator. If there is enough coolant in the radiator that means your car coolant system is working properly. Over time, due to the rust and sludge, you could find the coolant not clear enough as it should be. Most of the cars need a flush every 30000 miles or five years, whichever comes first. But the best thing is to do to follow the owner’s manual for exact schedule. You should flush your coolant with a proper concentrated coolant whenever you do it.


How do you know that your car is Overheating?

Driving should be safe and comfortable for all drivers, but the worst feeling is the undeniable fact that something is wrong. Lights flashing on your dashboard, red mark in temperature gauge, steam spewing from under the hood, and warning bells chiming are the signs to indicate that the engine is too hot. You should pull over onto the interstate shoulder or into the nearest parking lot. There might be a sinking feeling in your stomach – you could be facing expensive repairing cost. Overheating is the worst enemy of your vehicle engine. Heat damage might be very severe and require a complete engine replacement or overhaul if the condition is not caught in time. There are few common signs that your car is overheating and what should you do next.


Dashboard Warnings

Every vehicle has a temperature gauge to show the temperature of the coolant in your engine. Generally, the temperature gauge has mark indication “C” for cold and “H” for hot. If your engine starts overheating, the needle on temperature gauge will be pointing towards the “H” or “ Red”. In newer cars, there is a warning light- an icon that resembles a thermometer- on the dashboard that comes on when the car begins to overheat. Unfortunately, warnings on the dashboard aren’t often noticed. Still, if the thermostat is not broken or faulty, the car should be indicating that the engine is running hot.

Overheating Symptoms

Steam or Smoke

Smoke or steam might start coming out under the hood when your vehicle overheats. Always keep in mind that your cars can overheat without steam or smoke, but if there is, it is a sure sign that your car is too hot. Even exhaust pipe might emit steam. Sometimes, you may notice a burning smell which comes from under the hood.

Hot Air from A/C

If your car is running and the A/C is on, you can also find out if the car is overheating or not. Usually, if your car’s coolant is low, the hot air will come from the A/C. It doesn’t mean that your car is overheating, but it is a telltale sign that your vehicle needs more coolant to avoid becoming hot.

Coolant and Oil Check

If your car is leaking coolant or oil, this might be an issue for your car to overheat. When your car is parked, leaking coolant or oil would be pooling under the car. So make a habit of checking for a coolant puddle whenever you get in the car.


The engine emits a bubbling sound as coolant enters the overflow container if your vehicle overheats. This strange noise might indicate the presence of air in the cooling system. It often leads to overheating down the road.

What to do if your car Overheats  (Step by Step)

Overheating is a common problem in the car. Drivers who have experience having a car that overheats may know what to do and how to avoid them. But those who are recently experiencing or having a hot engine or temperature problems, this might help them to prepare for the unexpected situation. Vehicles typically overheat during the summer time or hot weather. If you have a sudden temperature rise or leakage, don’t know what to do in traffic or what if the needle’s in the red, you need to consider the steps mentioned as follow:

1. If you have overheating problem while driving:

  • • If you notice that the car is overheating, turn off the air conditioner and open the window to decrease the heat and cools the engine.
  • • If it continues to overheat, turn the heater and blower on so that the heat from the engine can transfer to the passenger compartment.
  • • If it doesn’t work and is safe, then pull over as soon as you noticed the temperature gauge creeping into the “Red” or “H” territory.
  • • Turn off the engine and open the hood/bonnet of the vehicle. So the air can cool the engine down.
  • Check the coolant reservoir tank and if the tank is low, fill it up to the max. On most cars, you can add coolant/ liquid even if the engine is hot.

Extra Tips


• If you have a leak in the coolant reservoir, carefully and slowly open the radiator cap. Hold the lid with a cloth to protect your hand. Once it is open, refill the radiator with cold spare coolant but do not use water into a hot radiator- it could cause the engine block to crack due to the sudden temperature change. If there is no other option for you, add water slowly while the engine is running in neutral or park.


• In some cases, if you have coolant leakage out of the water tank or from any other cooling system, you may start the engine while the radiator cap is open and refill the radiator with more cold coolant. But you need to be very careful to do that and need an expert direction to follow the procedures. Close the radiator cap once it is full and check the temperature gauge whether the level is dropping or still the same or getting high. If you notice that the engine is still in high temperature and smoke or steam coming out of the engine, you better stop the engine and call for help.

• Call the road assistance or tow truck to help you to get back to your destination.

• It is recommended not to drive the car in that situation. But if you have nobody around and could not contact the assistance, then drive the car in steady mood turning the A/C off and the heater on.

Overheating Car

2. If you have overheating problem when you are in traffic

When the car begins to overheat, the situation could be much stressful. It is important to let your cooler head prevail and might follow these tips-


· In a stopped traffic, when you keep the engine running in gears, the engine gets hotter as the water and air can’t get through it. So put the car in neutral or park and rev the engine a bit in stopped traffic. So water and air flow through the radiator to cool the engine.

· In a stop and go traffic, try to move at a steady slow pace than to go fast, stop, go fast, stop, etc. Accelerating and riding brake will increase the load on the engine which will cause severe damage to the car. Drivers will not compromise in stop and go traffic because everyone is stuck in the same traffic. If you are in rush hour traffic, then pull over the car in stop and go traffic. Turn the engine off and wait for the traffic to starts moving again. When you drive, it is better to drive faster than slower as more will come into engine and helps to cool it down.

How to avoid your car from Overheating?

Driving a car with overheating problem is very annoying and stressful. People spend a lot of money to enjoy their ride but the indisputable fact that the car can get an overheat problems due to many reasons and substances. But if you ought to prevent the car from getting this hassle on the road or the trip, you should follow some of the preventive steps on your own and your mechanic help.

How To Stop Overheating
  • Check the coolant level regularly to see if the level is fulfilled.
  • Always check the engine oil level with oil stick to identify any oil leaking.
  • Watch your temperature gauge while you are driving and make sure it doesn’t go past above the halfway mark.
  • Check the drive belt or serpentine belt whether it is cracked or worn out.
  • Clear your radiator if you find any leaves, bit dirt or giant mosquitoes and clean it with pressure cleaner or blower.
  • Inspect the radiator cap carefully to find any weakness or fault in spring or shape.
  • Don’t use the air conditioning in very hot conditions if your car battery is not healthy. 
  • Turn the heater on to help to cool the engine.
  • Have a mechanic perform regular coolant flushes and inspected the vehicle for potential problems.
  • Always carry a bottle of coolant or water, a car kit, a cloth and contact number for road assistance for the emergency.

Consequently, Overheating can be caused by a few different factors. The simplest cause may be that your car needs more coolant. Yet depleted coolant can be caused by the bigger problem, like leaks or faulty hoses, so always check for the underlying cause before simply filling it up with more. Another common reason for overheating may be that the radiator fan which keeps your engine cool is faulty, so check your fan motor connection and fan thermostat.


About the author


Hello, My name is Andrew David, a passionate car lover, and enthusiast.
I am not so called expert but love to share my experiences and knowledge regarding the car and motor parts for all vehicles.