How To Fix Overheating Car [5 Quick DIY Fixes]

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Several things can cause your engine to overheat. And as a driver, it’s your duty to figure out exactly which problem is causing it so you can solve it. In some cases, overheating is something you can tackle on your own without consulting your mechanic.

Sadly, cars tend to overheat at the most unsuitable time, which is usually when you’re in haste, and you’re stuck in traffic. Suddenly, the needle will start to rise, together with your blood pressure. It’s never a fun experience.

In this article, you’re going to learn how to fix overheating car. This will help you to better understand your vehicle and be ready for the event of your car overheating.

What Makes a Car To Overheat?

As I mentioned earlier, there are many things that can make your car to overheat. Below are some of the possible causes to always look out for:

  • There’s a leak
  • Improperly circulating coolant
  • A hose needs replacing
  • Malfunctioning thermos stat
  • Internal debris in cooling system
  • Malfunctioning cooling fan
  • Damaged radiator
  • Blocked air inlet to radiator

What Happens When a Car Overheats?

Basically, as the coolant temperature in your car rises the Engine Control Unit, the computer running the car engine will start taking some precautionary measures to protect the engine.

While this is happening, the ignition timing will reduce, and the amount of fuel injected into your engine will increase.

These measures will, to a small amount, minimize the amount of heat generated, but will significantly prevent detonation or knock from destroying the crankshaft, pistons, bearings, and rods to death.

What Do I Do When My Car Overheats?

What Makes a Car To Overheat

First of all, you don’t want to panic when your car starts to overheat as that won’t solve the problem, but will only increase your blood pressure. Instead, calmly pull over to the roadside and turn your A/C off if it’s on.

But if, for some reason, you can’t pull over, turn your heater ON, this will draw in the warm air from the engine and discharge it into the cabin. At this point, it’s advisable to roll down the car windows to avoid overheating yourself.

When you get somewhere safe, pull over and open the car’s burnet and let it cool for some minutes. After the engine cools down, carry out a visual inspection of the bay to see what actually caused the issue (we’ll cover this in detail below).

Now, let’s look at how to fix overheating car by first diagnosing the problem.

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How To Fix Overheating Car

If you’re unable to prevent your car from overheating (which is often the case) and you had to experience it, the first step is to diagnose the issue, as I mentioned earlier.

First of all, watch the video below to see how the critical components in a vehicle’s cooling system function.

The key to detecting any fault in a car is always to first have a good understanding of the system you’re working with. Once that is done, you’ll be well-positioned to fix the problem.

That said, the primary culprits in any cooling system are:

  • Bad water pump
  • Malfunctioning fan
  • Stuck thermostat
  • Coolant leaks
  • Bad radiator cap seal
  • Contaminated fluid
  • Bubbles in the cooling system
  • Head gasket leak

1. Car Overheats Only At Low Speeds

If your vehicle only overheats at low speeds only, probably when you’re driving around the city, there’s a chance you’ve got an airflow problem.

This happens when there’s little ram air passing through the radiator at low speeds. In this case, you will want to check and confirm that your vehicle’s fans are cutting on.

If you have a mechanical fan, you need to ensure that your fan clutch is actuating. Watch the video above to see how that can be done.

2. Fan is Working, Revving the Engine Brings Down the Temperature

If your fans are working properly, and you discovered that slightly revving the engine at idle brings the coolant temperature needle nosediving, there’s likely a coolant flow problem.

To diagnose this, allow the engine to completely cool off, then examine both the radiator and the overflow bottle to ensure that you have enough antifreeze. And if it’s not sufficient, check if there are leakages in the system. In particular, check and see whether the water pump seal has failed.

You also want to check where the plastic end tanks of the radiator mate up with the aluminum core, the radiator hose clamps, and most importantly, the radiator cap to see if its seal has failed.

If the leak is not much, you could just add more coolant as a temporary solution until you are able to replace whichever part is responsible for the leak.

Although it’s worth noting that loss of coolant isn’t always caused by an external dribble, it can also happen due to a leak within the engine caused by a cracked head or a bad head gasket.

There are a few ways you can check this, which includes:

  • Check if there’s white smoke coming out from the exhaust pipe and if the car is idling poorly. If that’s the case, then coolant is probably getting into the combustion chamber.
  • Check if the oil level is too high or milky. And if any coolant is remaining in the bottle or radiator, check if it looks brown. If so, it means that the coolant and oil could be mixing.
  • Perform a compression test using a gauge, which you can rent from your local car parts store, or buy one from Amazon. If there’s low compression on two adjacent cylinders, there’s a possibility that the head gasket between them has blown. As you’re checking that, see if any of the spark plugs appear as if they were steam cleaned – and if so, coolant could be entering the cylinder.
  • Get a radiator pressure tester and pump in some air to the cooling system. If it doesn’t hold any pressure, see if there are external leaks. If there’s none, then a bad head or head gasket could be the culprit.
  • Run the engine with the radiator cap off; check to see if the pressure from the cylinder is leaking into the cooling system; this would manifest itself as bubbles in the radiator, indicating a bad head or head gasket.

If you discover that the fans work properly and there’s enough coolant in the system, but somehow, revving the motor still drops the coolant temperature, then a coolant leak may not be the issue. The problem may have something to do with coolant flow or quality.

There’s perhaps a broken water pump impeller, which you can diagnose by listening for sounds near the water pump. This means that the antifreeze flow rate is very low, leading to an overheating condition.

Furthermore, the coolant may be polluted with dirt, which can significantly reduce its heat capacity, clogging up coolant passages. The best way to diagnose this is to open the radiator cap (when the engine is cold) and check to ensure that it looks clean.

You also want to crank the engine and by looking and listening to the serpentine belt pulley on the water pump, check if it is squealing or slipping. If so, it might be that your engine is not turning the pump fast enough to circulate fluid.

If there’s enough coolant on the car, the heater works well, you didn’t notice any noise on the water pump or pulley, revving the engine reduces the coolant temperature, and the coolant looks clean, there’s a possibility that air is trapped in the radiator hoses.

In that case, you may need to take the car to your mechanic so he can remove the air from the bleed ports.

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3. No Coolant Leak, Fans Work, & Revving the Engine Does Nothing

If you enough clean coolant, your fans work flawlessly and revving the engine at idle does not bring your engine’s temperature down, you probably have either a dead water pump or a stuck thermostat.

The water pump can be checked by turning on your heater; if it is blowing out approximately ambient air temperature, then your pump is probably faulty.

But if the heater works well, the next step will be to squeeze the radiator inlet hose once the engine has heated up to its usual running temperature and see if feel hot.

Check if it feels like coolant is flowing through it at all. And if the inlet hose of the radiator does not feel hot or pressurized, your thermostat may be faulty.

This means that instead of transferring engine heat out of the radiator, the cooling system of the car continues to circulate it through the engine over and over again, overheating the engine eventually.

The next stop will be to consult your mechanic.

NOTE: Most of the things mentioned here regarding fixing an overheating car requires some level of confidence and expertise. If you feel it’s not something you can handle on your own, then it’s best you reach out to your mechanic to avoid creating more damages to your car.

Watch the video below to learn more about this:

How To Prevent Your Car From Overheating

Having gone through how to fix an overheating car, let’s quickly look at a few measures you can always take to prevent your vehicle from overheating.

While you might not be able to avoid it altogether, the tips below will significantly reduce the chances of your vehicle overheating.

  • Replace the coolant on-time
  • Use the right coolant
  • Replace the radiator on-time
  • Replace the thermostat
  • Replace the belt(s)
  • Replace the water pump on-time
  • Replace hoses on-time
  • Check the radiator cap
  • Check the coolant temperature sensor(s)
  • Keep the engine and transmission maintained
  • Don’t block the radiator
  • Check the bumper inlets
  • Replace damaged / missing liners and guides

Frequently Asked Questions

How much does it cost to fix a car that is overheating?

For most cars, it may cost between $500 to $1500 to fix an overheating vehicle. This cost covers things like replacing the radiator, head gasket, or water pump and changing the heater core.

The repairs may be even costlier if you have a specialty engine or a diesel.

Can I still drive my car if its overheating?

No, you cannot. You want to avoid driving with an overheating engine at all cost. If you must drive a car with an overheated engine, do so only after the engine cools down.

What happens if your car overheats and you keep driving?

If you keep driving with an overheated engine, the cylinder heads will eventually start to warp, leading to the top/head gasket blowing up, leading to more severe problems. Of course, this would require an expensive and lengthy repair.

Is my engine ruined from overheating?

Yes, overheating can ruin your engine if taken lightly. You need to act fast if your engine is constantly running hot. This can cause a lot of grave damage, such as a warped cylinder or cracked head gasket.

When your car’s head gasket is cracked, antifreeze may go everywhere, damaging the engine.

Can a car catch on fire if it overheats?

No, a car cannot catch fire if it overheats, except there are other problems with the car.

How long does it take for a car to cool down after overheating?

It takes about 30 minutes or more for an engine to cool down enough to be safe to handle.

Can I use water instead of coolant in an emergency?

Yes! You can use water as a coolant; however, this is not recommended because water won’t work well enough beyond its boiling and freezing points.

Further Reading:


Overheating car is something no one will ever wish to experience. I wouldn’t even wish that to my enemy as I know how devastating it can be.

However, it’s not something you should panic for, as I stated earlier. I advise you always to monitor your car temperature whenever you’re driving. And whenever you notice that the temperature is rising more than required, simply pull over and see what’s happening.

And if it’s not something you can handle yourself, call your mechanic to come for your rescue.

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