Can A Coolant Flush Cause Problems?

Regular maintenance is one of the significant reasons why vehicles run smoothly and ultimately reach their lifespan. The coolant flush is a significant aspect of keeping your car running efficiently.

A coolant flush, crucial for car health and longevity, should be considered when a pressure test indicates a malfunction or the thermostat shows overheating. It is an essential maintenance service that car ownership demands, ensuring that components like hoses, radiator, and the engine remain in optimal running condition. This maintenance can prevent problems on the road, much like a blood transfusion revitalizes a body. While a DIY kind may appeal, a professional mechanic’s check and services assure thoroughness.

However, there are contemplations about the implications of this maintenance service. If you’re wondering, “Can a coolant flush cause problems?” This article unveils the truth about the general notion.

can a coolant flush cause problems

What Is A Coolant Flush?

A coolant flush is a car maintenance service that removes dirt, sludge, rust, and other contaminants from the cooling system. The flush typically expels all used coolant materials from your car’s radiator so you can refill the component with fresh coolant.

Your car’s health is at the mercy of the coolant fluid exchange. The radiator flush is a major part of the entire maintenance equation. It helps to get rid of everything hindering your engine from cooling correctly.

Can A Coolant Flush Cause Problems?

Can a radiator flush cause problems? A coolant or radiator flush is not expected to cause any problems because the maintenance service was designed to enhance a car’s engine performance and efficiency. However, it can cause severe problems if it is not accurately done.

If you fail to flush the cooling system thoroughly, the radiator flush can lose up existing contaminants to clog up the cooling system. As a result, instead of enjoying an enhanced engine performance after the coolant flush, the system can suffer from the effect of clogs.

Could Flushing Cooling System Break Thermostat?

Flushing a vehicle’s cooling system will not affect the thermostat, provided the task is correctly performed. However, several complications may arise from a coolant flush if you don’t understand the cooling system and how to do a radiator flush.

That is why it is very essential to consult a professional auto mechanic to do the engine coolant flush. However, if you’re a DIYer and you’ve successfully performed a couple of repairs on your car, it may be relatively easy for you than a car owner who has never handled a repair exercise.

Is A Coolant Flush Necessary?

Of course, a coolant flush is necessary! In fact, flushing your car’s cooling system is extremely important because it helps to expel whatever could get in the way of the system’s operation and hinder the car’s engine performance.

So, if you don’t want to battle engine problems like overheating or coolant is exhaust, ensure to flush your vehicle’s radiator at regular intervals, depending on your manufacturer’s manual recommendations.

How To Do Radiator Flush 

Performing a cooling system flush is not rocket science. However, you can do the task with precision if you know the procedure. Therefore, the following is a step-by-step guide to perform your car’s radiator flush correctly.

Step 1: Park, turn off the vehicle and jack it up.

Firstly, park on leveled (plain) ground and turn off your car’s engine. Then, allow it to cool down for about 30 minutes before commencing the coolant flush.

After that, get a solid jack, raise the front of the vehicle, and hold it up with jack stands. Meanwhile, kindly wear your safety kits before touching anything to avoid accidents. Wear your rubber hand gloves and safety glasses.

Step 2: Pop the hood open and locate the radiator.

Open the hood and locate the radiator in front of the engine. It is usually a long metal tank with a pressure cap. Once you locate the radiator, carefully twist the pressure cap counterclockwise to open it.

Step 3: Open the drain plug to release the old coolant

Now, reach out for the valve or plug underneath the radiator by the driver’s side under the bumper. Once you locate the valve, carefully open it to allow the fluid to drain gradually.

You may need a wrench or screwdriver to do this properly. Meanwhile, place a bucket under the radiator to collect the liquid. Once the flow stops, carefully fix the drain plug in place.

Step 4: Pour distilled water and radiator cleaner into the radiator

Get a recommended radiator cleaner and distilled water. Pour the radiator cleaner with a funnel into the radiator, followed by the distilled water. After that, put the pressure cap back on the radiator.

Step 5: Start the car’s engine

Insert your car key in the ignition and turn on the engine. Ensure to keep the heat on full blast. This process can be for around 5 minutes to allow the cleaner and distilled water to work their way through the cooling system and eliminate any excess coolant.

Step 6: Turn off the engine and drain the cleaner/distilled water

Turn off the engine and allow it to cool down for a while. Then, drain the cleaner and distilled water mixture in the radiator via the drain plug hole. Also, keep the bucket under the drain plug to collect the liquid.

Repeat the process of flushing the cooling system (this time with clean tap water). Then, again, start the engine, allow it to run for a while, and turn it off. Then, open the pressure cap and drain plug to release the fluid.

Step 7: Refill the radiator with coolant and distilled water mixture

Now, get a gallon of pre-mixed coolant consisting of coolant and distilled water in a ratio of 50/50. If you don’t have this, you may want to get a gallon of coolant and distilled water to prepare the mixture in another gallon in the same ratio (50% each).

After that, pour the coolant into the radiator from the hole where you removed the pressure cap. Again, ensure to use a funnel to avoid wastage. Meanwhile, you may have to turn on your car’s engine on full blast as you continue to fill to let the fluid go straight into the cooling system.

However, check your owner’s manual for the maximum quantity of coolant you need in the vehicle’s radiator. Then, you can top it off gradually until you hit the recommended max point. After that, replace the pressure cap on the radiator.

How Often Should You Do A Coolant Flush?

You should do a coolant flush every 3 – 5 years or 30,000 miles. However, consult your vehicle’s owner’s manual for your car’s recommended coolant flush interval.

Nevertheless, expert auto technicians recommend an interval within the time frame stated above for a maximum satisfactory result. If you notice smoke under car hood, it is a sign of flushing. Meanwhile, flushing a radiator system is a tricky task that must be done carefully.

How Much Does It Cost To Flush A Radiator?

The radiator flush cost is estimated at around $100 – $200, depending on the auto technician you contact.

A dealership will be relatively more expensive than an independent auto mechanic. In any case, kindly contact a professional who can handle the job without any complications.

What Happens If You Don’t Flush Coolant?

If you don’t flush a car’s coolant, especially at the recommended intervals, the radiator will automatically become corroded or rusty. It can also generate debris in the cooling system.

cooling system flush

When this occurs, it will eventually affect the cooling system and the engine negatively. Therefore, ensure to flush your car’s radiator at the recommended intervals to prevent complications in the engine performance.


A coolant flush is as essential as having the fluid in the cooling system in the first place. Neglecting this maintenance service will eventually affect your car’s engine performance in the long run.

However, kindly follow the procedures above when flushing your car’s radiator. If you’re not a DIYer, you may want to contact a professional auto mechanic to do the job.

Meanwhile, if you know anyone asking – “Can a coolant flush cause problems?” Ensure to recommend this article to them.


Mr. Shafiqule Islam is a graduated Mechanical Engineer and has more than 15 years experience of repairing and maintenance of different brand vehicles like Toyota, Mitsubishi, Ford, Mercedes, BMW etc. He is also giving training to Mechanics. He has started writing to share his practical knowledge to Vehicle Owners, Drivers and Mechanics to keep their cars at best fit.

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