How To Flush Cooling System With Garden Hose?

A car’s performance can be affected by various factors including local environment, and even sediments. The engine must be kept cool at all times so that it does not overheat.

As the car is used over time, lots of deposits and sediments may build up in the radiator. This is why a car owner is advised to maintain their car by flushing the radiator every once in a while as a standard maintenance precaution.

Why Is It Important To Flush Your Radiator System?

Most cars’ radiators and heaters are made from aluminium metal. Aluminium may not rust; however, it can be corrosive if submerged in water for long periods. Other radiators made of other materials may rust. This is why car owners need to flush the radiator after every 50,000 miles.

To flush the radiator, you can use a garden hose since it’s effective in removing rust and all other sediments that have been building up over time. Using a garden hose will keep the radiator clean and prevent rust from accumulating. To ensure the longevity of the radiator, you may also need to apply great protection from corrosion.

Build-up obstructs the radiator’s and engine’s water passages, causing engine overheating. When the engine overheats, sometimes it may lead to engine seizure, a situation where the engine shuts down and fails.

Essentials Required To Flush the Radiator

  • Antifreeze tester
  • Products for flushing the radiator, for instance BlueDevil Radiator Flush
  • Distilled water to refill (use water if your antifreeze is not premixed)
  • A garden hose
  • Gloves
  • Utility knife
  • Suitable coolant or antifreeze
  • Drain buckets
  • Good flow of water
  • Goggles
  • A tester for checking the level of antifreeze
  • Old rags

Flushing the Radiator Using a Garden Hose

Flush Cooling System With Garden Hose

Before you start working on the radiator, you must park the car on a level surface. Do not start flushing if the engine and the radiator are not cool to the touch. Operating car coolants can be toxic; therefore, you are advised to take the necessary precaution. Also, wear gloves and put on the googles for maximum protection.

You can flush your radiator in two ways, either using the regular method or the back flushing method. The back flushing method removes any built-up grime that may have settled in the cooling system’s smaller parts.

In this article, we will look at both methods of flushing the radiator. Read on.

Regular System Flushing

Regular System Flushing

  1. Start by opening the radiator filling cap which is found at the top part of the radiator. You can also open the cap on the expansion tank if it’s present.
  2. Place your drain bucket below the drain valve or the petcock so that the waste coolant does not spill on the ground.
  3. Run the liquid into the drain plug, emptying it into a bucket to drain the radiator.
  4. Close the petcock or the drain once you are done running the liquid
  5. Refill the radiator flush treatment into the top radiator cap. Then, fill it with water from your garden hose until it reaches at least an inch below your radiator’s neck. The manual on the chemical treatment should guide you further.
  6. After flushing, tighten the red and pressure cap located at the expansion tank.
  7. Start your engine and run it for a while. Also, turn the heater on high so that the thermostat can open and allow the water and flushing treatments to flow within the system.
  8. After around 10-15 minutes, turn the engine off and allow the vehicle to cool down properly.
  9. Use a bucket to catch and drain the drain plug and pressure cups. Loosen the hose clips to remove the top and bottom radiator hose.
  10. Place your garden hose on the top hole of the radiator and seal using rags.
  11. Flush it with water until the sediments come out and the water becomes clear.
  12. Add pre-diluted coolant onto the valve or make a mixture of distilled water and coolant.
  13. Run your engine until the bubbles stop showing and the level of the coolant rises. Replace the radiator screw-on cap
  14. You can add more liquid into the expansion tank if the level has gone down.

Flushing Using the Back Flushing Method

Flushing Using the Back Flushing Method

  1. The Back flushing method is useful in dislodging stubborn sediments within the cooling channels and the thermostat housing.
  2. There are many backflush kits available in the market, which you can use on your radiator.
  3. Start by cooling the engine and de-pressurizing it.
  4. Use a utility knife to cut through the heater inlet hose. Clip the hose clamps found in the kits to the heater core and the engine top.
  5. Fit the T-fitting from the kit, and tighten the hose clamps using a screwdriver
  6. Fix the T-fitting to the black side of the backflow prevention, and connect the garden hose to the yellow side of the coupling. Do not pass the garden hose anywhere near the moving parts.
  7. Fix the splash tube and any other plastic tube so that the water can drain away from the car.
  8. Drain the wastewater into the drain buckets.
  9. Ensure that the faucet is bringing water into the splash tube.
  10. Start the engine and turn the heater on high. Allow the water to pass through the system.
  11. After the water runs clear, turn the engine off and disconnect the plastics and the garden hose.
  12. Do not forget to drain all the water by opening the drain valve, then closing it after you are done.
  13. Add in your premix after changing the coolant and ensure that it reaches the maximum level in the car’s expansion chamber.

Checking if the Job Is Done

You can use a pressure tester to check if the whole system is able to hold the proper amount of pressure. Holding pressure means that there are no holes where air can enter or the coolant can spill out. Therefore, you must ensure that you let the bubbles rise until they are out of the neck.

When there is too much heat, for instance, in the summer, you must ensure that the system is holding pressure as expected so that the system does not overheat.

If you want to check the pressure of the system, open the radiator; check if the overflow reservoir is filled with enough coolant. Fit the pressure tester into the opening and pressurise the entire system until you see the coolant flowing out of the overflow lone.

Do not go beyond the prescribed maximum amount of pressure or overflow your reservoir cap. Hold the pressure tester for a while, checking that the coolant is not leaking. Once you finish, replace the cap and put the heater controls on high to warm the car.

If you want, you can clean your radiator on the outside. Start by removing the radiator from the car and connecting the garden hose to a pressure washer suitable for such work. Use the pressure washer to run water through the aluminium fins to get rid of any dust or dirt that may have accumulated. The accumulation of dirt can affect your radiator’s cooling capacity.

You can also clean the aluminium fins separately by brushing the loose dirt using a nylon brush, to make sure you do not damage the soft, metal core. If the core is greasy, use oil dispersant on it or smear an oil solvent using a soft brush. Clean gently until you eliminate all the dirt, dust, and grease.

How to Tell If the Radiator Needs to Be Flushed?

You should check the condition of the coolant in the reservoir regularly. The colour and consistency of the coolant should tell you if the radiator needs flushing. Murky, thick, and cloudy coolant indicates that replacement is needed. Other warning signs include:

  • A warning light of the coolant that indicates it’s low on the dash
  • The vents releasing cool air after you hot set the car
  • The engine temperature gauge moving to the red zone slowly
  • A warning light from the check engine.

Benefits Of Flushing the Cooling System of the Car

  1. It helps to remove harmful deposits and scale that can result in serious engine issues. A flush raises the deposits and scale-out making the cooling system perform at the optimum level.
  2. Lubrication of the moving parts in your cooling system. The lubrication will help to extend the life of these moving parts; for instance, the water pump.
  3. Flushing ensures that the temperature and corrosion protection of the engine is improved. If you use a good quality coolant, you will protect your engine better from high/low temperatures as well as corrosion, which helps it to perform better and have a longer lifespan.
  4. Flushing helps you to know exactly what is in your engine. People who buy used cars may find it difficult to know the kind of coolant in the system or if it is of better quality. Once you replace your cooling system, you will know exactly the type of coolant responsible for protecting the engine, and you will also know how to mix the fluids properly.

Final Thoughts

If you want to save money, you can flush the cooling system using a garden hose on your own. You only need to follow the steps listed above and after doing it a few times, the process will become quite easy.

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3 thoughts on “How To Flush Cooling System With Garden Hose?”

  1. Thanks a lot. This article is so useful. A radiator plays an essential role in keeping the temperature of our car at a safe level. The condition of our radiator will affect the car’s engine and the air conditioning system, so it is best to take care of it. Doing this work by myself will help us to save money. Nice!!

    • Hi Jessica,
      Thanks for your feedback. Delivering valuable information is what drives us, and we’ll continue to work hard to create content that adds value. Stay tuned for more!

      Good luck! ❤️

  2. Depending on the state of my radiator, a radiator flush will cost me around $50-$150. I want to save money and do this procedure on their own. That’s why I want do it by myself.


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