How To Flush A Radiator With A Garden Hose

Local environments can affect a car’s performance, and none more so than keeping the engine cool so that it won’t overheat. While there are many things you need to take your vehicle to the garage to have done. You can do some things at home with fundamental auto parts to help extend your vehicle’s life and save money.

Because the cooling system is so critical to a vehicle’s performance, your vehicle can benefit from flushing radiators in cars, trucks, or other vehicles that use conventional combustion engines.

It may sound hard to clear out the entire gunk from your radiator, yet in practice, with a suitable quality garden hose, the job doesn’t take long, and the steps are easy to follow. Here, we look at how to flush the cooling system with a garden hose.

Why Do I Have to Flush My Cooling System?

Modern vehicle engines are made of aluminum, from cylinder heads, water pumps, engine blocks, and more. Two other key components, such as the radiator and heater, are aluminum. Although aluminum does not rust, it can suffer corrosion by submerging underwater for prolonged periods. To last, it needs excellent corrosion protection to ensure its survival.

When periodically flushing the radiator and replacing the coolant (antifreeze), you should add the coolant from the radiator in the correct 50/50 ratio of coolant and distilled water. This helps prevent radiator overheating in summer and freezing in winter.

Over time, this sediment begins to block the water channels in the radiator and engine. Once these blockages reach a certain level, they lead to overheating.

If this happens at severe levels, it can lead to the engine shutting down and failing. Corrosion inhibitors (antifreeze) come in green, red, and orange. Red and green provide about two years of use, while orange offers more time.

However, if your car already has green or red, you can’t just add orange without flushing the system first. (Read What to Do When Lawn Mower Won’t Stay Running)

Things You’ll Need

• Recommended coolant or antifreeze for your vehicle
• Drain buckets
• Garden hose with a good flow of water
• Radiator flushing products
• Gloves and goggles
• Antifreeze level tester
• Old rags
• Sharp utility knife

Once you have the above, park your vehicle on a level surface. Both the engine and your radiator need to be cool to the touch.

Ensure no pets or children are around; these vehicle coolants are toxic.

Flushing Vehicle Cooling Systems

When you are looking to flush the radiator, you can see two ways to do this. One is the regular way, and the other is a backflushing radiator to remove built-up grime that settles in small parts of the cooling system.

Here, we will show how you can flush a radiator to keep your car running cool or without freezing in the cold.

Radiator Flush and Coolant Change

Here are the easy-to-follow steps for regular coolant system flushing.

1. Open the radiator-filling cap that is located on the top of the radiator. If your vehicle has an expansion tank, open the lid on that, too.
2. Check to find where the radiator drain valve or petcock is located. Position your drain bucket underneath so you can catch the waste coolant.
3. Open the drain plug and let all the liquid run into the bucket to drain the radiator. Once empty, close the drain or petcock.
4. In the top radiator cap, add the radiator flush treatment. After you add this, use your best garden hose to fill the radiator until it is one inch below the neck of your radiator. Make sure you check the instructions on the flushing chemical bottle.
5. Close both your rad cap and the cap of the pressure cap on the expansion tank.
6. Start the engine and run until it is at running a temperature. With your heater control, turn your heater on full blast. Running the heater on high causes the thermostat to open and lets the water and flushing liquid flow around the system. Some motorists also remove the thermostat to achieve the same thing. Please leave it in place, and it gets clean.
7. After ten minutes of running, please turn off the engine and let your vehicle stand until it is cool to the touch.
8. Open the radiator drain plug and pressure caps, and catch the flushing water into your bucket. If no water drains, use a piece of wire to poke because you may have sediment buildup.
9. Remove both the top and bottom radiator hose by loosening the hose clips.
10. Place your garden hose in the top hole of your car radiator. Use the rags to make a good seal.
11. Flush the radiator with tap water until all the dirt comes out and the water clears.
12. Close the drain valve and top up with pre-diluted coolant. You can use distilled or regular water to make up the 50/50 concentration. Distilled doesn’t contain salts that make up the sediment.
13. Run the engine until the coolant no longer bubbles and the level begins to rise. Replace your radiator screw-on cap.
14. Top up the expansion tank if the level is not by the maximum level.

Back Flushing Your Coolant System

The first method does an excellent job of cleaning and draining the radiator, yet you may need to backflush the entire system.

This will dislodge any stubborn sediment from inside the engine cooling channels of the block and thermostat housing.

To make this easier, you can purchase backflush kits suitable for most vehicles and trucks. Aside from this, it would be best to have an excellent radiator cleaner and the items listed before the regular method.

Here are the straightforward instructions to backflush your system:

1. Ensure you are close to a drain or have your drain buckets handy.
2. The engine should be excellent and de-pressurized by removing the upper radiator cap.
3. Cut through the heater inlet hose with the utility knife at the straightest point. This runs from the heater core by the firewall to the top of your engine. Add a hose clamp from the kit to each cut side.
4. Add the correct sized T-fitting (various sizes come with the kit) and fasten the hose clamps with a screwdriver.
5. Connect the black end of the backflow prevention coupler to your T-fitting. Take your best water hoses and connect them to the yellow end of the coupling. Be sure your garden hose is away from moving parts.
6. Connect the splash tube. You can also add another plastic tube, allowing better drainage away from your vehicle.
7. Use your drain bucket or open drain for the wastewater.
8. Open the drain plug that is located at the lowest point.
9. Turn on the faucet and check the water coming from the splash tube.
10. Start your engine and turn the heater to full. Let your vehicle idle as the pump pushes water through the engine system.
11. Water will eventually run clear after the vehicle runs for around 10 minutes.
12. Once you see clear water, you can turn off the engine and remove the garden hose, the splash tube, and the backflow prevention coupler from the T-fitting.
13. Open the drain valve and let all the water run from the system. When empty, you can close the drain valve and the T-fitting on the flushing fitting with the included cap.
14. You can now change the coolant with your premix of 50/50. Be sure the coolant level of the new antifreeze mix is by the maximum level in the expansion chamber.

More Radiator Cleaning

Once you change the coolant, you need to check there are no leaks from your backflush parts, the bottom, or the upper radiator hose. You must monitor the levels over the next few weeks to ensure they stay at the proper levels.

While doing these coolant changes, some vehicle owners clean their radiators on the outside. To do this, remove your radiator from the vehicle and connect your garden hose to the best pressure washer ideal for these jobs around the home.

With your pressure washer, you can fire the water through the aluminum fins to clear dead flies, insects, and any dust accumulation. All these can affect the cooling capacity of your radiator. From start to finish, you can clean the entire system in your vehicle and add new coolant. The whole process takes three hours maximum. (Read Starter Fluid Spray Guide)

You can save quite a bit of money by doing it yourself, and you can know it is done right.

Tim Graham

With over 20 years of hands-on gardening and landscape design experience, Tim Graham, the founder of YardandGardenGuru.com, is dedicated to sharing expert advice and fostering a vibrant community for garden enthusiasts. His award-winning designs and sustainable practices reflect a deep-rooted passion and expertise in horticulture. Connect and cultivate your green thumb with Tim!