Reading Time: 7 minutes

You can tell that you have a clogged radiator once you start observing signs such as overheating and inefficient cabin heating. But why wait for this to happen when performing simple radiator maintenance can help you avoid this altogether?

As was mentioned, a clogged radiator can cause your car to overheat and may eventually lead to engine damage. This is why it’s essential to learn how to clean a radiator properly—by cleaning the external fins every year and flushing it according to the manufacturer’s maintenance schedule.

mechanic wearing gloves holding a radiator cap
A clogged radiator can cause overheating, which could result in engine damage.

You can find the recommended service schedule listed in your owner’s manual. Usually, in the manual, you’ll find a radiator flush listed as a “coolant service” or something similar.

Best Way to Clean a Radiator

If the cooling system isn’t serviced according to OEM scheduling (coolant change intervals), the system begins to become contaminated with rust, scale, etc. to the point that the tubes in the radiator begin to clog.

Furthermore, the fins on the outside of the radiator can clog with dirt and debris so that air cannot pass through the fins. The problem is that the A/C condenser is in front of the radiator so that you can’t see it just standing in front of the vehicle most of the time.

There are two ways to clean the radiator: internally and externally. The latter involves cleaning the radiator fins located on the outside while the former has to do with flushing out old fluid and all the buildup that may have accumulated inside of the radiator.

Each one entails a specific process that we’ve broken down in this guide to help you clean your radiator thoroughly.

How to Clean Radiator Fins

First, let’s start with the outside of the radiator. This involves the removal of any dirt, pebbles, bugs, and other foreign material on and around the fins on the front of the radiator.

Getting rid of any debris that has accumulated on the exterior of the radiator ensures proper airflow, which is essential in lowering the temperature of the hot coolant (also known as antifreeze).

Note: Before performing any maintenance on the radiator, make sure to consult the factory repair information and follow the instructions outlined by the manufacturer.

Using a spray bottle

1. Let the radiator cool

Make sure that the radiator is completely cool to the touch before starting the cleaning procedure.

2. Dilute cleaning solution with water

The ratio of the solution and water is relative to the brand of product you get, so make sure to check the back label of the cleaner for further instructions.

3. Transfer the solution to a spray bottle

Once you’ve prepared your diluted solution, pour it into a clean spray bottle.

4. Apply the solution

Spray the prepared solution on the radiator fins.

5. Use a brush to clean the fins

Get a soft-bristled brush and carefully clean up any debris that has accumulated in and around the radiator fins. Exercise caution to avoid bending the fins out of place.

6. Straighten any fins that were bent out of shape

If you see any fins that are bent or deformed, carefully take a flathead screwdriver to restore them to shape. You may also use any thin implement such as an ice pick, a barbecue skewer, or even a toothpick.

7. Rinse with clean water

If you’re using a hose, make sure to set it to low pressure to ensure gentle cleansing. Repeat steps 1 to 3 until the water turns clear after rinsing.

8. Allow to dry

Let your radiator fins air dry.

Using a hose

Alternatively, you can also use a hose with a nozzle to wash outside of the radiator. Just like the method above, wait until the radiator has completely cooled down, then brush the radiator fins using light pressure. Make sure to use a soft nylon brush and do not go against the direction of the fins.

Once you’re done, get your hose and rinse everything out, allowing the water to stream from the outside in.

And just the same, allow it to air dry.

cleaning radiator external clog with water from garden hose
Rinse everything out from the radiator using a hose.

How to Flush a Radiator

Choose the right coolant flush or cleaner product so that don’t end up damaging your radiator or your engine. Refrain from using chemicals that could potentially be abrasive, such as vinegar and bleach, as both will make the body prone to rust and corrosion.

Once the body of the radiator gets corroded, surrounding components such as the engine head, rubber gaskets, and seals can get damaged.

Warning: Never remove the radiator cap or attempt to service the radiator when the engine is hot. Serious injury may result.

1. Allow the engine to cool down

Ensure that the engine is completely cool before starting with the procedure.

2. Jack up the vehicle

Safely raise and support the vehicle using a jack and jack stands. Chock the rear wheels and set the parking brake.

3. Drain the coolant

Place a catch pan under the radiator. Then, loosen the radiator petcock valve to drain the coolant.

4. Run the flush solution through the radiator

Close the radiator petcock valve. Next, follow the instructions on the flush solution to properly dilute the product, then run it through the radiator and cooling system.

Typically, the process involves mixing the product with water, adding the solution to the radiator, then running the engine for 10 minutes or so with the heater on high.

Be sure to keep an eye on the temperature gauge during the process. If the engine starts to run hotter than usual, shut it off immediately to avoid damage.

Note: It’s a good idea to use distilled water rather than regular tap water when diluting the flush solution.

5. Drain

Allow the engine to cool. Then, remove the radiator cap and drain all of the flush solution out of the cooling system.

6. Run water through the radiator

Close the radiator petcock valve again. Then, follow the instructions on the flush solution regarding the next step: running water through the radiator.

Typically, the process involves adding distilled water to the radiator, then running the engine for 10 minutes or so with the heater on high.

Again, be sure to keep an eye on the temperature gauge. Shut it off immediately if the engine runs hotter than usual as this can lead to damage.

7. Lower the vehicle

Remove the fluid catch pan. Then, safely remove the jack stands and lower the vehicle.

8. Refill the radiator with antifreeze/coolant

Allow the engine to cool. Then, refill the radiator and overflow bottle with the correct type of pre-diluted coolant. Do not add straight coolant to the radiator—the product must be a pre-diluted 50/50 mixture.

You can determine which type of coolant is best for your vehicle by consulting your owner’s manual or referring to your local dealership.

pouring antifreeze into coolant reservoir
Refill the radiator with the recommended coolant once the engine has cooled down.

9. Start the engine and monitor cooling system operation

After you’ve refilled the cooling system, start the engine and monitor the temperature gauge for an extended period of time. Should the engine begin to run hotter than usual, shut it off immediately to avoid overheating.

If the engine starts to run too hot, either the coolant level is low or air got into the cooling system during the flush.

Air can be bled from the cooling system by following the vehicle manufacturer’s recommended procedure (usually found in the factory repair manual). You can also bleed the system of air by using a vacuum-fill tool and compressed air.

How Often Should You Flush Your Radiator?

You should flush your car’s radiator according to the manufacturer’s maintenance schedule (outlined in your owner’s manual). As a rule of thumb, most automakers recommend flushing traditional green coolant, which is technically called inorganic additive coolant, every two years or 50,000 miles.

On the other hand, automakers usually recommend flushing modern organic acid technology coolant every five years or 150,000 miles. Once again, consult the manufacturer’s service schedule to know when to flush your radiator.

Benefits of Flushing Your Radiator

It goes without saying that flushing your radiator comes with a lot of benefits. Here are a few:

Clearing of rust and scale build-up

Doing a radiator flush helps you get rid of rust and scale deposits that accumulate as time goes by. This prevents overheating that could possibly happen when these deposits are left unattended.

Gets rid of contaminants

Cleaning your radiator also helps remove old antifreeze that could probably contain contaminants. When left unnoticed, these contaminants can bog down the cooling system. Thus, it is important that these are flushed out regularly.

Instant check-up

If you have the flushing or cleaning done by a professional, it’s likely that you’ll also get your entire radiator checked. The good thing about this is that you would be able to get everything done in one go.

Prevents rust and foam from forming

The additives from newly refilled antifreeze will stop rust and foaming in the cooling system. This way, the entire system will be able to function at its optimum.

Radiator Maintenance: How to Keep Your Radiator in Good Shape

Now, you wouldn’t want all the effort you spent on flushing your radiator to go to waste. You’d want to take better care of your radiator now so you can enjoy consistent performance from your cooling system.

Here are some tips you can look into:

Always top up your radiator fluid

Make sure you always have an adequate amount of radiator fluid. See to it that your coolant and water is always 50-50 in ratio. If you do not want to take chances with the proportion, you can always get a ready-made mix from your trusted auto supply shop.

Make sure the radiator cap is attached securely

This is to ensure that the coolant chamber remains pressurized, thus avoiding leaks and other problems.

tightening radiator cap
Securing the radiator cap ensures the coolant chamber is pressurized.

Schedule the flush and oil change at the same time

To make it a point that you flush your radiator as often as you should, schedule it at the same time as your oil change.

While it can be tempting to follow internet tips that teach you how to clean a radiator with baking soda, it can do more harm to your car than good. It’s best to just stick to the steps and tips outlined above than experiment with so-called hacks that do not guarantee success.

Products Mentioned in this Guide

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic.

File Under : DIY Tagged With :
Discount Already Applied
Enjoy the all-season versatility of Bestop's Core Doors NOW and Learn More
Notify of
Inline Feedbacks
View all comments
Copyright ©2021, Inc. All Rights Reserved.