How to Fix an Overheating Car Engine

If your car is over-heating then today’s your lucky day because I’m going to show you how to fix a car that overheats.

How To Fix an Overheating Engine in 6 Steps

Now many things can cause a car to overheat, so let’s start with the basics. Before you start, please make sure that your engine is cold. If you are not very handy, please call a friend to help you out.

1. Check The Radiator Fluid.

First, we are going to check the radiator fluid level. When the engine is cold, take the radiator cap, and look inside. Please make sure your engine is completely cold. Trust me, you don’t want to do this if your engine is hot. You may see some fluids, or you may not.

If it’s bone dry, fill a bottle with water and fill your radiator just to see how much fluid your radiator is lacking. This means that there is a leak somewhere and you will need to find it and fix it. The next step shows how to check and see where is the leak.

2. Pressure Check The Radiator System

So, the next thing to do is to pressure test the system to check for leaks. I’ve had this pressure testing device for many years. You can check it out on

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You can either perform this test by yourself or you can take it to the mechanic. I prefer doing it myself because it’s not much of a big deal. Just hook it up to the radiator, then pump up the pressure. And in this case, you can see it’s leaking right out of the radiator.

The radiator is just full of holes. Now, this case is pretty easy. There was a hole in the radiator. But if it was more complex, you watch the pressure on the gauge and see if it starts to move down.

Pump it up to 16 lbs. pressure or so, and watch the gauge. And if it starts dropping, you know there’s a leak and you have to find where the squirt is coming from. But let’s say you pressure tested it and there weren’t any leaks at all. What do you do next?

3. Check The Radiator Cap

The radiator caps are built with the sole purpose, to hold pressure in, so if they’re worn and rusty like the one that I had, you might just need a new radiator cap. There is a big selection on Now there are machines that test radiator caps, but, hey, they’re so cheap, just go buy another one and stick it on.

Now if that doesn’t fix it, the next thing to check is the cooling fans.

4. Check The Cooling Fans

Start the car up and then turn the AC onto full blast. And then check the cooling fans to see if they’re working back there. At this point, you may see both of your cooling fans to be working, or maybe the left or the right fan isn’t working.

If the fans aren’t working, there won’t be enough air sucked through the radiator and it will overheat. If they don’t work, then you have to check the fan motors. They often burn up. To check to see if the motor is out, just get a little jumper wire and stick one end on the positive cable of the battery and stick the other plug on the red cable that feeds the motor as shown below.

If the fan doesn’t start spinning, you’ll know the motor is burned out.

5. Check The Thermostat

But let’s say the fans are working fine. Well, then you might have a bad thermostat. These thermostats close so the engine warms up. And when it gets hot they’re supposed to open up. And sometimes they stick. Most thermostats are pretty easy to get to. On this Toyota, you just follow the bottom radiator hose, and there’s the thermostat housing back here.

It just has a bolt on the top and a bolt-on on the bottom. You pull it out and replace the thermostat. You can order a new one on And then you better hope a new thermostat fixes your overheating problem, because if it doesn’t, then you have one of two rather expensive problems.

Either the radiator itself is just so old it can’t dissipate heat anymore, or the head gasket on the engine is starting to blow. Now these modern radiators, they’re made of plastic and aluminum, often corrode inside, and don’t dissipate heat anymore.

They don’t leak and they look perfectly fine, but they just can’t get rid of the heat. You can order a new radiator on And as expensive as some radiators may be, you better hope the radiator fixes it, because the only other thing can be a bad head gasket. And in that case, you have to completely dismantle your engine apart. And that can cost well over $1,000 on most modern cars.

6. Perform a Combustion Leak Test

So before you turn the engine down, it’s a good idea to do a combustion leak test on it to make sure the head gasket is leaking. You can find a test kit on

It’s a simple test where the blue liquid is put into a tube and then the engine is run to see if the blue turns yellow. If it does, you’ve got a head gasket leak. In this case, the liquid stayed blue, so the head gasket is fine. So the next time your car starts overheating, don’t get mad.

Get under the hood and fix it. I have given you a complete guide on how to perform these tests. Don’t run to the mechanic that will charge you a lot of money for these tests. Perform them yourself and if you are not comfortable with fixing it, only take it then.

Have you had any issues with an overheating engine before? Please share your experience in the comments.

Is your engine oil due for a change? Visit our Car Fluid Guide Website to learn the importance of changing your oil on time, which type of engine oil is best for your vehicle, and much more.

Car Care Hacks

Hi there. I am a certified Automotive Service Excellence (ASE) mechanic since 2018 and a car detailer for 10 years.

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