How to flush the heater radiator

Flushing the heater radiator Tips

Flushing the heater radiator

How to wash the heater radiator with your own hands, without removing it?

Is your car heater not working properly? It may be caused by a clogged heater radiator.

Don’t worry you can do the heater radiator flush yourself using the right equipment and the right methods. We have written this guide on how to flush your heater radiator. Use it to clean your heater radiator without any problems.

Flushing the heater radiator

What you need to know before flushing the heater radiator

Flushing the heater radiator is required after about 100,000 miles of mileage, or if the heater has started to heat poorly. You can flush the radiator either by removing it from its seat or without removing it. When washing on your own usually use citric acid, whey, caustic soda, boric or orthophosphoric acid, and at service, stations use special agents.

Why are the heater radiators clogged?

The cause of a clogged heater radiator lies in the coolant. Firstly, in any antifreeze with the time of operation the spent additives precipitate out, and secondly, when the liquid is heated, the scale gradually appears, and it can also cause corrosion of the surfaces of all elements of the engine cooling system. As a result, all that debris accumulates in the thin tubes of the heater radiator honeycomb. If the coolant or antifreeze is of good quality, these processes take place very slowly; if the liquid is of bad quality, it is not just the radiator, it is possible to ruin the engine in a couple of years.

Radiator clogging is one of the most common causes of poor performance of the cabin heater. Most often it happens because of low-quality coolant, mixing of two different types of antifreeze or using water.

All this leads to the formation of plaque on the walls from the inside. Dirt clogs up the already thin radiator tubes with swirlers, disturbing the circulation, and no heating is out of the question.

How do you know if the problem is a clog?

To check whether the radiator is really clogged is quite simple. You need to find two thin pipes, going to the cabin through the bulkhead of the engine compartment, and feel them. If one of them is hot and the other is barely warm or cold, it’s a clog.

In some cases, there will be cold air blowing from the heater even if both pipes are hot. This can mean the following: everything inside is clogged so badly that the heated antifreeze gets into the radiator tank and bypasses the honeycomb and immediately leaves it, not having time to give off heat.

What to do about it?

The standard solution to this problem is to replace the radiator with a new one. This is what will be recommended in a car service center. You will have to pay more, because the cost of works is added to the price of a new radiator, and it is 2-3 times more expensive than the spare part itself. In modern cars, it is not so easy to reach the radiator: you have to remove the trim and the torpedo, unscrew the air conditioner tubes, and then refill it.

The second variant is flushing directly on a car. In this case, everything is much easier and you don’t need to remove anything. It is enough to disconnect the pipes going to the heater, connect a pump with hoses instead and run the flushing solution through the radiator.

flush the heater radiator

Flushing the heater radiator without removing it

It is easier to flush the heater radiator without removing it. To do this, use one of three methods – using two plastic bottles, with the help of a suspended large plastic bottle, or with the help of an external water pump. The described methods allow you to create pressure in the radiator, under which the cleaning fluid will circulate inside it.

Flushing with a plastic bottle

The method of flushing with plastic bottles allows you to flush the heater radiator, in two ways – in the removed state and directly in place from under the hood. For the work, you need the following tools: two 1.5-liter plastic bottles, a cleaner for the radiator, four clamps. The essence of the method is that the flushing liquid is poured half in the radiator and one bottle, and run it alternately from one bottle to another by pushing with your hands or feet on the bottles. In this way, its inner cavity is cleaned. The method is very simple and effective. When the liquid is very dirty – it must be replaced with a clean one.

flush the heater radiator

Another method is to cut off the bottom of a large plastic bottle, thus creating a watering can from it. And hang it higher, thereby creating pressure for the fluid flowing out of it. Connect one hose to the neck and the first spigot of the radiator, and the second hose, to the other spigot of the radiator and into the bucket on the floor. For tightness, it is desirable to fasten the hose on the radiator spigots with clamps.

When flowing from the height, the cleaning fluid under pressure will clean the inner cavity of the radiator. Continue until the new liquid is clean enough.

Flushing the radiator with a car pump

One of the most effective methods is to make a device based on an external liquid pump, with the help of which a constant circulation of detergent inside the radiator under pressure is ensured.

To make a device you will need: a car pump with electric drive, three hoses, which diameter corresponds to the outputs of the radiator and the pump, a battery charger, an immersion heater (which should heat the liquid), and a container for the solution, filtering element (synthetic sock or stocking), cleaning composition, stand under the container with the solution at the level of the pump.

Connect with hoses the pump (in/out), radiator (input/output pipes), and the basin with a warm cleaning solution. Put a filter sock on the end of the output hose. Start the pump, from the terminals of the battery, so that it “pumps” the liquid in a circle. And do not forget to connect the charger to the battery, as it has a heavy load.

This will create a looped system that will circulate the cleaner around the radiator. It is recommended to “run” the fluid for an hour in one direction and an hour in the other direction. After that, replace the fluid with clean fluid and repeat the procedure again. When you are done, rinse the radiator with boiled or distilled water for half an hour per side.

All the described methods can also be used if the heater radiator is dismantled from its seat. This will not only allow you to clean it under pressure but also by simply pouring special cleaning agents into it. In addition, the additional advantage of dismantling is that the car owner will have the opportunity to remove debris, as well as to inspect it for damage and corrosion pockets.

What to flush the car’s radiator?

In modern cars, heater radiators are made of two main materials – copper and aluminum. For aluminum radiators, it is necessary to use acidic means, and for copper – alkaline compositions. Do not use alkaline solutions for cleaning aluminum radiators, because its surface will immediately begin to oxidize, and the situation with clogging will only worsen or even ruin the part!

A list of products that can be used to wash aluminum and copper furnace radiators:

  • Citric acid
  • Vinegar
  • Lactic acid or whey
  • Battery electrolyte (radiator does not have to be disassembled when washed)
  • Caustic soda (radiator must be disassembled by flushing)
  • Phosphoric acid (radiator must be disassembled by flushing)
  • Boiled or distilled water
  • Special professional cleaners

Heater radiator flushing with citric acid

Citric acid can be used to clean radiators of any metal, both aluminum and copper. There can also be several proportions and recipes for its application. One of them is to take 20-40 grams of dry acid and dissolve them in one liter of water. If the radiator is heavily clogged, the amount can be increased to 80-100 grams per liter (increase the volume of the flushing mixture proportionally). Ideally, the acid solution should be checked with a litmus paper – the pH-factor value should be equal to 3. This is the optimal composition for cleaning the heater radiator.

The acid solution can be used according to the methods described above, pouring it inside. As an option pour it instead of antifreeze in the car and run the engine for 30-40 minutes, letting it idle or drive, then leave it for the night. Then drain the fluid, if it is very dirty (with a lot of sediment) the procedure should be repeated one or two more times. After that flush the cooling system with normal distilled water and pour in new antifreeze.

Vinegar flushing

Acetic acid is another available and effective tool for cleaning both the cooling system as a whole and the heater radiator in particular. For the flushing solution, you will need 500 ml of table vinegar, which must be dissolved in 10 liters of boiled or distilled water. The rest of the steps can be acted upon in a similar manner to flushing citric acid. Such a composition is suitable for radiators made of both copper and aluminum.

Washing with whey

The lactic acid that is available in whey perfectly cleans the plaque, rust, and debris from the walls of both aluminum and copper radiators. But in its pure form lactic acid is difficult to find, so it is easier to use natural (this is very important!!!) whey.

To clean the heater radiator you need 5-10 liters of it. Before using the whey you need to strain it through a filter a couple of times to remove pieces of fat from it!

Most often it is poured into the system and rolled for about half an hour, and then drained and flushed with hot distilled water several times, because the whey contains grease.

Flushing the furnace radiator with electrolyte

Battery electrolyte is also a good way to wash out various deposits and scaling. Almost any electrolyte in sufficient volume can be used. It can be used to clean both copper and aluminum radiators (but not for very long). When working with the electrolyte it is necessary to wear working clothes, rubber gloves, a respirator, and safety glasses.

When removing the radiator, the electrolyte is poured into it and left for a couple of hours so that a chemical reaction can take place, in which the dirt and plaque will dissolve. Then it is poured out and washed. Only the first time the water was used should be with a small amount of baking soda. And then it is advisable to use a cyclic “run” of water through the insides of the radiator.

Caustic soda flushing

Caustic soda is a caustic alkali and can have several names, caustic soda, sodium hydroxide, and caustic soda. It can not be used to clean aluminum radiators, only copper radiators, and even removed from the car because it is detrimental to aluminum parts of the cooling system.

A 10% solution of caustic soda is used for radiator cleaning. When making it, you need personal protection equipment, as caustic soda can cause chemical burns if it comes into contact with the skin. The obtained solution should be heated before use, and then pour it in and leave it for several hours, then drain it. If necessary, repeat the procedure two or three times until the liquid poured out is relatively clean. When finished, be sure to flush the radiator with clean, boiled or distilled water.

How to Wash with Phosphoric Acid

For cleaning aluminum and copper heater radiators are also well suited to orthophosphoric acid, and more precisely its 85% solution, sold in specialized stores. It is used on radiators that were removed from the car. You must wear personal protective equipment, gloves and a respirator.

You just need to pour the acid inside the radiator and leave it there for a couple of hours. After that rinse well with boiled or distilled water. It does not corrode the metal, and instead dissolves the plaque and rust inside.

Rinsing with Water

The simplest, but most ineffective remedy is plain boiled (this is important) or distilled water. But if you just want to wash your radiator with water, you must do it under pressure. In its pure form it is usually not used but only as a rinse after any of the means.

Special product for flushing a radiator radiator

For those who do not trust the old methods, manufacturers of car chemistry have already made ready-made tools specifically designed for cleaning the cooling system of the car.

For example LIQUI MOLY Kuhler-Reiniger or Hi-Gear Radiator Flush.

How effective is the radiator flush?

The radiator cleaning is much easier, faster, and definitely cheaper than the replacement, but this procedure has its disadvantages. Flushing is not a panacea, the chances of success are about 50 to 50. In neglected cases, sometimes there is no effect.

On older cars, the radiator can leak just because deposits that have closed the holes in the tubes will wash out. Well, there is always a chance of dirt from the cooling system getting back into the flushed heater.

Still, before replacing the radiator, many car owners prefer to flush it first.

How to flush the radiator without removing it?

Preparing for Flushing

Almost everything you will need for cleaning can be found in any garage, buy in the nearest store.

  • 150-200 grams of citric acid
  • 8-10 liter bucket
  • Antifreeze drainage tank
  • hose about 3 meters long
  • clamps
  • wires
  • mesh, gauze
  • water
  • antifreeze for refill
  • transfer pump
  • kettle or stove
  • wrenches
  • screwdrivers

Flushing process

Principle of flushing the heater radiator

The heater is disconnected from the cooling system and a pump with hoses is connected to it. In a separate container, the chemical is dissolved and heated, and then the flushing fluid is circulated through the radiator with the help of the pump. This dissolves and flushes out all accumulated dirt.

To keep debris from getting inside again, it is collected at the outlet and removed with an improvised filter made of gauze or old kapron tights. The radiator is then flushed with clean water and the original cooling system hoses are reinstalled.

Remove the terminals from the battery

When removing the radiator hoses, you may have to disconnect some wiring connectors. Therefore, to avoid control system errors, it is better to de-energize the onboard network by removing the terminals from the battery. Firstly – minus, and then – plus.

Preliminarily make sure that the heater is set on maximum heating. If it is controlled with a faucet, in the closed position it will block the flow of fluid and interfere with flushing.

Remove the terminals from the battery

Drain the coolant

The heater is filled with antifreeze. To prevent the fluid from leaking on the floor when you remove the spigots, it must be drained into a pre-prepared container through the plug on the main radiator.

As the heater is not the lowest point of the system, it is possible to drain not all the antifreeze but only a part of it. If you are careful you will be able to do it right through the pipes during the removal.

Drain the coolant

Remove the fuser connections from the heater radiator

Locate and disconnect the two thin hoses that go into the cabin. They are located between the engine and the engine compartment bulkhead. Usually, they are easy to find, but if you can not or are afraid to make a mistake – check the documentation for the car or search on the Internet.

Then just loosen the clamps and remove the tubes, turning them from side to side. Be prepared for some more coolant to come out.

Connect the hoses and pump

Take any appropriate diameter hoses (usually 16 or 18 mm), put them on the heater tubes, and secure them with hose clamps. The free end of one of the hoses connects to the pump, wraps the other in gauze, and lowers it into a container for flushing. Also, put a small section of the hose on the pump to draw in the fluid.

Prepare and heat the flush

To clean off dirt and scale, use specialized products, reagents for cleaning drains, caustic soda, and ordinary citric acid. The latter is the safest and at the same time just as effective.

Take 5-6 liters of water and pour 150-200 grams of the usual citric acid, stir well, and heat the solution. You can heat it with a kettle, on an electric stove, or from a gas burner. For maximum effect, the water temperature should be at least 170°F (75°C), or better, close to boiling.

Start the pump

Fill the pump’s intake hose with solution, quickly dip the tube into the container, and turn on the pump by turning on the power. Then the flushing process will begin: the liquid will circulate, draining into the bucket and coming from it again into the radiator.

If the heater is too clogged, at first the water will flow out of it in a weak trickle. Then as the solution is applied, the pressure will increase.

A full flush takes one to several hours, depending on the condition of the radiator. If the contamination is strong, you may need to change the solution to a fresh one.

The main thing is to change the direction of circulation every 15-20 minutes, rearranging the hoses on the pump. This will help flush out the maximum amount of dirt.

When a good stream of relatively clean water comes out of the radiator, the flushing can be considered complete.

Rinse the radiator with water

At the end of the process, you need to flush away the residual citric acid, so that it does not later mix with the coolant in the system.

To do this, just run a few liters of distilled water through the radiator. Drain the rest of the solution, rinse the container and then fill it with water and run the pump as in the previous step.

Pour in new antifreeze

After all the manipulation blows out the rest of the water from the radiator and disconnects the flushing hoses. Install the original hoses in their place and secure them with hose ties.

Check everything once more and make sure the plugs are closed. Next, pour in the antifreeze that was drained earlier, and if necessary add a new one – so that the level in the expansion tank corresponds to the norm.

Remove airlocks

When you remove the pipes and flush the cooling system, air locks will inevitably form in the system. With time they will come out by themselves, but because of them the heater can work with interruptions, so it is better to get rid of air at once.

To do this, it is necessary to drive up to an overpass or a steep hill, to raise the radiator of a car as high as possible, and to press the gas well a few times. At this point you will hear a gurgling sound inside the heater, which will stop after the plugs come out.

Check the heater operation

Warm the engine up well and evaluate the result. If the problem was really a clogged radiator and you did everything correctly, the effect will pleasantly surprise you. The heater will warm up like a new one, and the heat from the air ducts will start to flow in a couple of minutes after you start the engine.

Answers to Questions

How to understand that the heater radiator is clogged?

There can be many reasons why the heater does not warm up well. Including, it is due to its clogged radiator from the inside by the products of decomposition of the coolant. In order to check its cleanliness, it is necessary to check the temperature of the inlet and outlet pipes, running to the heater radiator, on the warmed up engine. Thus, if one of them is hot, and the other is cold, it means that the heater radiator is clogged. The clogging of the heater radiator will also indicate the fact that when they are both hot, the heater still blows cold air.

How can I flush the car’s heater radiator?

The heater radiator can be washed with or without removing it. In the latter case, the radiator is usually cleaned with a cleaning compound or an additional pump connected to the sockets and then washed with water.

What is the best way to flush the copper radiator?

The easiest method of flushing the copper heater radiator is to use a 10 percent solution of caustic soda (caustic soda, a mole for flushing plumbing pipes). Pour the hot solution inside for 30 minutes, then drain it. If necessary, repeat the procedure two or three times.

Also, a good result shows rinsing with a mixture of citric acid and vinegar. However, for an old copper radiator, it will be best to remove, unsolder it and mechanically clean it by hand.

What is the best way to wash an aluminum furnace radiator?

To wash aluminum furnace radiators, it is recommended to use acid-based products. The best options are milk whey, citric acid (such mixtures should only be very hot) or a solution of orthophosphoric acid (heated to medium temperature). And copper and brass heat exchangers will be safe only for professional products designed for flushing the cooling system of the car.

How to flush and what are the proportions for flushing the heater radiator with citric acid?

The proportion for flushing the car’s radiator with citric acid is 50 grams of acid per five liters of water. If the radiator is heavily clogged – the amount of acid can be increased to 80 grams. Pour the acid into 0,5 liter of boiled water, stir until it dissolves, and then adds the main volume of distilled water.

Pour the liquid into the cooling system instead of the antifreeze, warm the engine up to the working temperature, and then leave it idling for another 15 minutes. Then you drain and flush the system 3-4 times with distilled water.

How is it possible to wash the heater radiator without removing it?

Alkaline, acidic, or special cleaners are used for flushing the radiator. Alkaline compositions remove scale (lime), and acidic – rust.

How much does it cost to flush a furnace radiator at a service?

Different services, including, in different cities can assign different prices for the service of cleaning the furnace radiator without dismantling it. However, on average, the price of this procedure starts from $50. As for the time of the procedure, it is about two hours. If the radiator is heavily clogged – you may need more time, and the payment will increase because more cleaning products and workers’ time will be spent.

My friends and I created this site to tell you a lot of useful things from the world of cars. I worked as a salesman in a big auto parts store and gained a lot of experience in this field, now I am sharing my experience with you.

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