How to Flush a Radiator (& 4 Common Signs that You Need New Coolant!)

A car is one of our most important possessions. Like other assets, a car requires proper maintenance to run smoothly. Maintenance routines such as regularly checking up on your car engine’s air filter and rotating your vehicle’s tires are necessary not only in extending your car’s lifespan but also in ensuring your safety while on the road. One aspect that some car owners tend to overlook is the radiator fluid. This coolant is tasked to keep your engine running steadily under safe temperatures. It prevents your car from overheating, which could lead to even worse car troubles. Keeping the right amount of coolant inside your car is just as important as gassing up your vehicle.

In this article, we will discuss everything you need to know about radiator fluid, such as tips when adding coolant, how to flush it and signs that your vehicle needs a coolant flush.

Make sure to also check out our articles on Thermo King fault codes and Hibiscus trees – yes, we cover a lot of different topics on Atlantic Aspiration!

coolant being added to car

What does radiator fluid do?

Also known as antifreeze, radiator fluid is responsible for cooling your car’s internal combustion engine so your vehicle can run smoothly. It prevents your engine from overheating when the weather is too hot, as well as avoid freezing when it is too cold. Without it, the risk of damaging your car (and car parts) is severe. Antifreeze is generally a combination of propylene glycol or ethylene and water, with a 50:50 ratio. Other base types are also recommended by experts and we will discuss those in the succeeding subsections.

Why it’s important
Smooth running Avoids freezing
Prevents overheating Avoid car damage

So, how does radiator fluid work? Liquid coolant circulates through your car’s engine block and gathers heat from there. The heated fluid passes through a rubber hose and goes through the radiator. The liquid then cools via the air stream as it passes through the thin radiator tubes.

If you are driving on the road and your coolant malfunctions or runs out, this could cause damage to your vehicle’s engine parts, particularly the ones that are prone to overheating. These include your car’s head gasket, water pump, piston timing and cylinder head. While you can always have them repaired, you may have to spend a huge amount of money on something that could have been easily avoided through regular maintenance check-ups.

Radiator fluid is just one of the many types of fluids that run inside your car. These types include engine oil, which is a lubricant that allows your car to run smoothly; power steering fluid, which is responsible for lubricating your car’s steering gear; brake fluid, the one that adopts pressurized fluid for brake activation; and refrigerant, the fluid responsible for your vehicle’s A/C system. With all these types of fluids required to run inside your car, you may want to consider buying a waste oil heater to make better use of old oil instead of disposing it completely.

How long does coolant last in a car (& how often should you flush it?)

Now that you know how a coolant works and the importance it plays in maintaining your car, the next question begs: how long do coolants last in a vehicle? Unfortunately, there is not a one-size fits all answer to that question. Some say you have to change it every three years, while others believe it is best to flush the radiator fluid annually. However, there is a consensus that if your car is new and has only achieved less than 10,000 miles, then there is no need to perform a coolant flush.

Beyond this, there are different factors to consider when determining whether it is time to flush your car radiator’s fluid. Generally, car makers recommend changing your coolant every 30,000 miles. However, your driving habits also play a role in knowing the frequency of your radiator’s fluid changes. For example, if you frequently use your vehicle under extremely hot conditions, then you may have to flush the radiator fluid every 12,000 to 15,000 miles, or about once a year. Your car’s brand (and model) is another factor. Some Mercedes-Benz models need a fluid flush within a 30,000-mile interval, while others can last up to 120,000 miles. Meanwhile, coolants on most Chevrolets last after every 150,000 miles regardless of driving habits. For modern cars, it is typically advised to flush out coolant after 160,000 kilometers, while others may need a shorter mileage than this. You may want to consult your user manual or check with your vehicle manufacturer if you are still unsure when to change your coolant.

radiator inside a car

Does antifreeze go bad in your car

The lifespan of a concentrated antifreeze or coolant is indefinite. That is why you would not see an expiration date on the labels of coolant solutions that have not been mixed with water. On the other hand, pre-mixed coolant may expire within 3 years from the time of purchase. If you have a leftover coolant solution after refilling your car’s engine cooling system, make sure to store them in a secure container so it can last for years. However, there are storage guidelines that you need to keep in mind. First, use the original container when storing the leftover solution because its airtight lid helps keep contaminants at bay. Second, make sure to keep the containers away from children and pets as coolants are toxic and poisonous. Lastly, always label the containers so that you do not mix them up with other fluids in your garage.

But what happens when you have already added the antifreeze to your car’s cooling system? Does it start to expire right away? Once inside your car’s system, the coolant begins to degrade. Hence, experts recommend replacing or flushing out the coolant at certain intervals. This depends on the vehicle’s model, make and driving conditions. Generally, it is advisable to check on the quality of the coolant inside your car every 50,000 miles.

What kind of coolant does my car need

Just like when purchasing an engine-drive welder, a plasma cutter or a gasless MIG welding buying radiator coolant requires careful consideration to make sure your money is well spent. There are two things to consider when buying radiator coolant: type and base.

The two types of coolant are Type A and Type B. Type A coolant has an antiboil and antifreeze component. This coolant contains either propylene glycol or ethylene glycol to raise the boiling level while lowering the freezing point. Its inhibitor is used to protect your car’s cooling engine from rust, cavitation and corrosion. Unlike Type A, Type B coolant does not have emulsions or antifreeze to accompany its inhibitor, making it only effective for preventing rust and corrosion. However, some variants may have anti-cavitation agents for better performance. Type B coolant was very popular among vehicles launched before the 1980s.

Another factor to consider is the base and this can be classified into three: inorganic acid technology, organic acid technology and hybrid organic technology. If you are shopping for coolants, you may notice that they come in a variety of colors. This is because most car manufacturers add dyes to differentiate one base from another. Organic acid technology typically comes in orange, dark green, bright red and blue. This base does not have phosphates or silicates but it does have corrosion inhibitors to make the engine last longer. Car models manufactured by Nissan, Toyota, General Motors, Honda, Mitsubishi and Volkswagen usually use this base.

Inorganic acid technology, meanwhile, is typically used on older cars, particularly those made between the 1920s and 1990s. With corrosion inhibitors and silicates, this base takes care of the engine and radiator. It comes in bright green color and is advised to be flushed out every two years or about 30,000 miles. Another type of base to consider is hybrid organic acid technology. As the name implies, this base combines the previous two solutions and is recommended for newer car models. It has silicates to prevent corrosion, as well as additives to avoid rusting. This coolant is available in turquoise, purple, yellow, blue or pink color. One popular example of this is the Prestone antifreeze coolant, which helps prevent engine failure. This is a universal coolant that can be combined with another product without risking any damage. Many European- and Asian-made vehicles work great with this coolant. American-produced vehicles also work well with Prestone antifreeze coolant, including pick-up trucks like the Dodge Ram.

A rule of thumb when deciding the right coolant for your car is to consult your dealer. They are in the best position to determine the right coolant specific to your car model.

Signs that vehicle needs a coolant flush

Imagine yourself driving on the road when you noticed an odd smell from your hood that reminded you of maple syrup or you heard some noise coming from your car’s engine. Most likely than not, that is your car coolant telling you that it needs to be flushed out. Here are four common indicators that your car needs a coolant flush.

Signs you need coolant
Pancake-like smell Overheating
Leaking Coolant level emptying

The first telltale sign of a much-needed coolant flush is the pancake-like smell rising from the hood of your car. This is largely due to the sweet-smelling properties found in ethylene glycol. Overheating is also another sign to watch out for. If your car overheats easily even when you are not frequently driving under hot temperatures, then this is a sure sign that your coolant is no longer functioning properly and that you need to consider going to your mechanic to have your car checked. The third hint that your cooling engine system is compromised is leaking. If you notice tracks of colored liquid where your vehicle is parked, consult a professional mechanic immediately and have your car inspected.

Lastly, if your coolant level empties out earlier than it should, then there must be something wrong with your car. This is why it is important to regularly monitor your coolant reservoir to avoid having to top up repeatedly at shorter-than-recommended intervals. If you want to know how to check the coolant level of your car, check out the subsections below. And while you are scrolling, you may also want to check out our complete guide on the best wide belt sanders.

How to flush a radiator’s coolant (aka how to bleed your coolant system)

radiator of a car

Now that you know the importance of a car’s coolant system, the next thing to learn is how to flush a radiator’s coolant. Knowing when to flush the radiator coolant depends on several factors including car mileage, brand and model, and driving habits. Flushing out the radiator coolant during the recommended time interval is also important to prevent the build-up of debris and other unwanted contaminants.

Before starting to bleed your coolant system, make sure that you have the following tools:

  • Drain pan or bucket that has a capacity of at least 15 liters
  • Distilled water
  • Radiator flush solution
  • Fresh coolant
  • Wrench or screwdriver
  • A pail of water or running faucet
  • Safety goggles

First, wear your safety goggles and park your car on a flat floor or surface. Make sure that the engine is cool. If you are unsure about how long you should wait for the engine to cool down, skip to the next few paragraphs. Letting the engine sit for a while to cool down is important to prevent burns when opening the radiator cap. You also need to ensure that pets and children are out of sight since the coolant is highly poisonous. You may likewise consider a working area that is free from litter or away from distracting shrubs or vines.

Next, place your bucket under the drain plug, allowing it to catch the fluid spills. To bleed the coolant system, remove the cap of the radiator and the drain plug, which can be found at the bottom of the engine. This plug can come in the form of a petcock, bolt or a screw. Once the drain is open, allow the fluid to flow until the container is empty. Afterward, put the drain plug back to its original position and properly dispose of the spills caught by the drain pan. You may want to purchase a large container similar to a fuel transfer tank where you can put these waste spills so you can get rid of them later in an eco-friendly way.

The next step involves the radiator flush solution. Pour this solution via the open radiator cap and into the container. The radiator container must be filled in with water through your hose. Make sure that the water is about an inch below the radiator’s neck. Next, put the radiator cap back in and tighten it. Go inside your car and start the engine, allowing it to run for about 10 minutes. The gear must be on neutral before starting this process. Then, turn off the engine and let it sit for some time to allow it to cool down. Next, turn to your drain plug, open it, and let the solution flow out if it once more and into the newly replaced bucket under the radiator. As in previous steps, put the drain plug back in and tighten its cap. At this point, you may need to consult your user manual to know the capacity of your cooling system. Refilling the radiator with a fresh engine coolant may require distilled water if you are using a pure solution. Check the label of your coolant solution to be sure if it is already diluted. Once filled, close the radiator by tightening its cap and let your engine run for another 10 minutes. This will allow an even distribution of the coolant.

Flushing a radiator with vinegar

When checking your radiator, you may notice floating debris, bugs and other gunk that can cause clogged drains and block airflow. If not addressed properly, this could lead to overheating. Thankfully, there is one household item that can help solve this.

Aside from pairing it with cucumbers, vinegar can also be used to flush radiator fluid, among the many other things that this versatile solution can do! Vinegar contains mild acetic acid that works safe enough with metals. But just like other solutions, you have to use this ingredient in moderation to avoid damaging your engine. Vinegar can also be used to clean the main cooling system if there are calcium carbonate deposits, but since radiator coolants often use distilled water, the chance of having these unwanted contaminants is slim.

How long does it take for a car to cool down

The exact time it takes a car to cool down depends on different factors including the amount of engine coolant, ambient temperature and the kind of material the engine block is made of. On average, a car needs 1 to 2 hours after the engine is turned off for it to completely cool down. If you are planning on checking your car’s coolant level, then you may want to wait up to 5 hours. That is because even after the engine is off, the residual heat is still taking its sweet time to travel through the coolant.

Inspecting your engine while it is still hot can cause serious damage such as burns and scalds so having the patience to wait before opening the radiator cap is a must. You can also check your car’s temperature gauge to see if it is safe to inspect your engine, although this should be done with caution as it can sometimes give a false reading.

How much coolant does my car hold

Knowing the capacity of your car’s coolant radiator is one step closer to making sure that your engine runs smoothly. Thankfully, this is a straightforward process that you can do by yourself as this information should be available in your car’s user manual. On average, a car has space for more than 2 gallons of engine coolant. You can also manually check your car’s coolant capacity by flushing the fluid out of the radiator and refilling it with 1 quart of distilled water at a time. The water level should hit the piping of the expansion tank. After calculating the result, empty the radiator again and fill it with a coolant solution and water. You can refill the overflow tank to adjust the coolant level.

How much coolant should be in the overflow tank

A radiator overflow tank gathers the expanding antifreeze or coolant heated by the engine. Afterward, it recycles the coolant and passes it back through the coolant system once the heat level eases. The function of the overflow tank is connected with that of the radiator cap, both of which help in engine protection and avoid overflowing that could lead to coolant loss. Cars that do not have a radiator overflow tank are more prone to rust. An overflow tank must be filled with just the right volume of coolant to avoid leaks.

How to check the coolant level

As mentioned in the previous subsection, regularly monitoring the coolant level is important in making sure that your car runs smoothly, allowing you to avoid expensive repairs. If your car’s coolant level runs low faster than it should, then this could be an indication that your coolant is malfunctioning.

To perform a check-up, make sure that the engine is cool. This means that you cannot check the coolant reservoir while the vehicle is running. Allow a few hours after driving before you remove the radiator cap as doing otherwise could cause burns especially when the coolant is still hot. Next, check for markings found on the side cover of the plastic overflow bottle, which is directly connected to the car’s cooling system. This bottle has a bright cap, usually orange, and is transparent, allowing you to see the fluid it contains. The coolant level should be in between the markings that show the maximum and minimum fluid level. If the level goes beyond the minimum, consult your user manual to know the right type and base coolant for your car and refill the fluid right away. You may also consider flushing your radiator coolant, if you see debris floating inside or if the color of the fluid is rusty and brownish.

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