How To Do A Car Radiator Coolant Flush?

What happens if you don't change your coolant? And how to do it yourself at home.

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Radiators are a crucial part of your car’s cooling system. They help regulate your engine’s temperature at an ideal level, which prevents it from getting too hot and seizing up or not working correctly.

The cooling system in your car is essential for both performance and safety. Engine coolant circulates through the engine to keep it cool. It also runs through the heater core so you can stay warm in winter.

Coolant, or antifreeze, is a liquid that flows through your car’s cooling system and radiator to keep the engine cool. Coolant can degrade over time, leaving it less effective and needing a change. Not changing the coolant regularly can cause expensive problems down the road. Follow this guide to learn how to do a car radiator coolant flush:

Basic Steps Of Coolant Flush

Regularly doing radiator flush and refilling it with fresh antifreeze/coolant helps prevent corrosion, electrolysis, and internal engine rust that mineral deposits and poor water quality can cause. It will also help maintain a more efficient engine temperature.

car's performance, common workshop tools, metal tank, wear safety glasses, drain pan, parking brake

To flush the coolant, you will need:

A funnel

A new thermostat

A new radiator cap

New antifreeze/coolant

Distilled water

Drain pan

Old towels and rags

Here are some steps you can follow to perform your coolant flush:

1) Turn off your car and lift the hood.

2) Locate the radiator and unscrew the cap. If there is no cap, you may need to remove the hose that leads into the radiator or simply look for a low point on the radiator where you can drain it. Most radiators have a radiator drain valve somewhere on the vehicle’s cooling system. Once the drain valve has been located prepare a drain bucket because you will drain the radiator and the entire cooling system of the old antifreeze.

3) Allow it to drain out all the old antifreeze entirely into a bucket or pan. You will want to dispose of this fluid properly, so if this isn’t something you can do at home, make sure you have a plan for disposal before you start this project.

4)Once drained, get more coolant and fill up the radiator until full. This can be done through the same opening or through a funnel connected to one of the hoses if there is no cap on the radiator itself.

5) Repeat this process until all of the old coolants have been removed and the car’s cooling system is ready for fresh new coolant.

radiator, system, cooling, metal frame,

Types Of Coolant Flush

It is essential to know that flushing the radiator does not mean pouring clean water through it. A coolant flush involves using a chemical solution to remove mineral deposits, rust, dirt, and other debris from the radiator. This is accomplished by flushing out all the old coolant and then replacing it with fresh coolant.

There are three common types of coolant flush:

Drain and refill. This is the least comprehensive and cheapest type of flush since you simply drain the radiator and fill it with new coolant. Using this method, the old coolant can only be drained from the radiator, leaving most of the old fluid in place.

Chemical flush. This uses a chemical solution to break up deposits and force any remaining debris into suspension. Once there, the debris can be removed by flushing out the system.

Pressure flush. A pressure flush uses pressurized water or air to flush the radiator by forcing debris from its surface through the cooling system and out of it entirely.

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Choose the Right Antifreeze

With so many different types of antifreeze on the market, it’s essential to understand what they do and how they work. Some are designed to protect against freezing and others against overheating. Some offer both properties plus corrosion inhibition. And some are recommended for specific automobiles and others for general use. Most types of antifreeze contain ethylene glycol (EG). It is a highly toxic substance, so you need to be careful when handling it. Ethylene glycol works by lowering the freezing point and raising the boiling point of water. Most antifreeze contains additives, such as those that inhibit corrosion or lubricate water pump seals.

Choosing the proper antifreeze will protect your car’s engine cooling system, keeping it performing at its best. There are many brands of antifreeze available on the market today, but here at MyCar.Repair we carry only the best for our customers. We offer two products for antifreeze applications: LIQUI MOLY Anti Freeze Flush and LIQUI MOLY Antifreeze Concentrate (G13).

Choose LIQUI MOLY Anti Freeze Flush

This product is meant to be a complete cooling system flush. This means removing all impurities from your radiator, including rust, grease, and scale deposits, and replacing them with a new coolant. LIQUI MOLY says this will restore thermal efficiency in your engine, extend its life, and protect against corrosion.

How To Use LIQUI MOLY Anti Freeze Flush

LIQUI MOLY Anti Freeze Flush is a formula that will clean out your cooling system thoroughly. It cleans the cooling system and removes deposits, rust, and scale. It protects against corrosion and effectively prevents freezing. It contains no nitrates, phosphates, or silicates. This product is safe for all metals and plastics used in modern cooling systems.

Steps to use this product:

  • Add the entire content of one bottle to your cooling system.

  • Bleed the system completely.

  • Drive your car for approx 10-15 minutes.

  • Stop the engine and wait until it cools down (approx. 30 minutes).

  • Drain the old coolant and flush the system with clean water until no more residue comes out (approx. 5-10 min).

  • Fill in new coolant/water mix according to manufacturer’s instructions.

air pockets, engine components, dirty fluids

When Do You Need To Flushing Coolant

The engine coolant system is designed to keep the engine from overheating. This is done by supplying pressurized coolant to the engine’s thermostat. The thermostat opens and closes to regulate the amount of coolant that circulates through the engine and back to the radiator, where it can be cooled.

Over time, contaminants get into your coolant system, reducing its ability to protect your car’s engine. These contaminants include rust and scale deposits on your cooling system components, like your radiator, fluid pump, and heater. These contaminants can cause corrosion that attacks these components and causes them to fail.

Doing a car radiator flush and replacing the old coolant should be done every two years or so, but there are a few cases where it needs to be done more often.

With that in mind, here are five reasons you may need to get your car radiator flushed sooner rather than later:

1. It’s been at least two years since your last flush

2. Your car is overheating

3. Your car is leaking coolant

4. Your engine temperature gauge has been higher than usual lately

5. Your heat isn’t as hot as it used to be

local automotive store, pressure cap, splashing fluids, engine to cool

How Does Antifreeze Keep Your Car’s Cooling System Cool?

Antifreeze works by lowering the freezing point of water and raising the boiling point of water. When water freezes, it can damage all parts of the engine cooling system, including the radiator, hoses, water pump, and engine block. Antifreeze prevents these components from freezing and keeps your car running smoothly through winter. In summer, antifreeze raises the boiling point of the water to prevent it from overheating in high temperatures.

Antifreeze also contains rust inhibitors to prevent rust from forming inside the engine. Antifreeze needs to be appropriately mixed, with a 50-50 ratio of water and anti-freeze.

When mixed properly, antifreeze keeps your car’s engine between 195 degrees Fahrenheit and 220 degrees Fahrenheit. If the temperature gets too hot, the antifreeze boils into steam, which can cause damage to your car’s engine. If it gets too cold, the antifreeze freezes and expands, which can also cause damage to the engine.

What If The Engine Stopped Working Because Of It

If the engine stops working because of dirty coolant and the engine broke down, you should first pull over and shut the car off. If you are driving, it is likely that the engine has overheated and has caused significant damage. Shutting off the engine will help to prevent any further damage from being done. You should then call a tow truck, your mechanic, or both and tow the vehicle to a shop for repairs.

Dirty coolant can cause your engine to stop working. If the coolant is dirty, it will not be able to do its job of cooling the engine down and keeping it from overheating. This can cause the engine to overheat, leading to damage or even breaking it.

If your car has stopped working because of a dirty coolant and you want to get it back on the road as soon as possible, you will need to flush out the old coolant and replace it with a new coolant.

Another reason your vehicle might stop working because of dirty coolant is if there isn’t enough air going through the system. Without proper airflow, heat buildup can cause damage to other parts, such as your engine or catalytic converter.

If your car isn’t running correctly because of dirty coolant, you can try cleaning it yourself with a hose and some water pressure or using an engine flush product to help get rid of debris build-up inside the system.

How To Flush A Radiator?

There are a few key things you will need to do a radiator flush at home. First of all, you will need to get access to the radiator. You can do this by opening the hood and removing the cap on top of the radiator (do not open it if the engine is hot). You are now ready to start draining out the old coolant at the drain plug.

Once the old coolant has been drained, you can refill it with clean water and flush the system. Once this is complete, you can repeat this process until you feel that you have removed enough of the old coolant from the system.

Once this is done, you will now need to refill your radiator. This is best done using a funnel so that it does not spill all over your engine bay. Once filled, put back on the cap and any covers that may have been removed to gain access to your radiator (if applicable).

The next step will be deciding what type of radiator coolant/antifreeze you will be using in your car. If you are unsure, then it is best to check your vehicle manual for the correct coolant type or ask a mechanic or technician at a local auto store.

right coolant, hose clamp, radiator reservoir

How Long Does A Cooling System Flush Take?

The coolant flush procedure is a reasonably straightforward process.

The radiator cap and drain plug will need to be removed from the car radiator to start the process.

Then, the radiator must be drained of old antifreeze. Generally, four gallons of coolant are exhausted from the vehicle.

Next, water should be run through the cooling system to flush any remaining coolant residue.

After this is complete, a new thermostat and a new hose should be installed.

Finally, the radiator must be refilled with a new mixture of antifreeze and water. Generally, this mixture is 50/50, though this may vary in different situations.

Altogether, you can spend about 1-2 hours on a coolant system flush. This may vary depending on your skill level and if you have any complications along the way.

Benefits Of Flushing Your System By The Radiator Cap

But there are several good reasons why flushing your cooling system can be brilliant. One reason is that operating your car with dirty or contaminated coolant can harm your engine. Contaminated coolant can corrode your engine block and other parts of your cooling system and cause the water pump to fail.

In addition, flushing your radiator allows you to remove any rust or mineral deposits accumulated in the system over time. A good radiator flush will remove any chemical buildups in your engine’s cooling system. This ensures that your new antifreeze doesn’t become contaminated as soon as it goes into the system.

pressure cap, flush the radiator, tap water, full blast


A lot of cars come equipped with a radiator. Radiators typically will also have a plastic or metal cap that can be removed to do an engine flush. An engine flush is a procedure where you drain the coolant from the radiator and add a new coolant to it to remove any impurities and contaminants into the system. In doing this on your own, you may run into some problems. However, if you take your car to a professional garage or mechanic shop, they could perform an engine flush for you in no time at all.

As a final note, let’s review some of the benefits of performing a car radiator coolant flush. Doing so adds life to your car’s engine, saving you money in the long run. It helps remove corrosive particles and debris from your engine, preventing it from worsening. And it removes old coolants that may have developed harmful bacteria, helping to avoid a nasty infection. So despite what you might be led to believe, flushing your car’s radiator is a good thing that doesn’t take much time or effort.

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