How to Flush a Radiator With a Garden Hose

how to flush a radiator with a garden hose

Learn how to flush a radiator with a garden hose. You can flush a radiator with a garden hose when it is clogged to prevent overheating. The radiator is a part of the car’s cooling system.

A normal functioning radiator does the work of exchanging heat from fluid inside the radiator the air outside. Automatic transmission fluids and air conditioners make use of radiator to complete this process.

The most common reasons why radiator gets clogged is either because of dirt or radiator oil itself. If you car’s radiator gets clogged there would be no flow of coolant or antifreeze through the cooling system thereby causing overheating.

Lets flashback a little to the common causes of overheating in a car. In my previous article about overheating we learnt the causes of overheating includes leaking coolant or antifreeze, a blown gasket and a loose radiator cover.

Things needed to flush a radiator with a garden hose


  • A pair of hand gloves
  • Container to drain the cooling fluid into
  • Brand new antifreeze or coolant
  • A meter long garden water hose
  • Distilled Water for Refilling (unless new antifreeze is pre-mixed)
  • Antifreeze tester
  • Radiator flushing product

All the above listed items are all you to successfully flush a radiator with a garden hose at home. All the items are very important and necessary except for that of the pair of hand gloves.

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how to flush a car radiator using a garden hose

If you are using a old radiator in your car then it is possible to have dirt inside it that would cause the radiator to clogged. In this article we will see the most common causes of been clogged and how to flush a radiator with a garden hose.

The radiator fluid too can clog the radiator if the engine is not run for a prolong period of time. If the radiator fluid stays stagnant for a long time it starts to create rust and sediments that blocks the radiator fins and hoses.

Follow the guide below to get started and flush a clogged radiator with a garden hose. This guide will help you save money as you can do it at home

  • Disconnect lower hose under the radiator
  • Drain the cooling fluid into a container
  • Now seal the lower radiator hose with a pices of rag
  • Make sure the radiator cap is put back and covered as expected
  • Disconnect the upper radiator hose
  • Now connect your garden hose and fill the system with water
  • Remove the rage used to cover the lower hose earlier and let the water drain out
  • Now plug the garden hose back and flush the system out until its clean
  • Use a glass cup to collect the water from the last flash to see how clean it is
  • Repeat this process until a desired result is archived
  • Fit the respective hose back when after flushing
  • Now pour a 50% distilled water and 50% antifreeze into the coolant reservoir
  • Cover the radiator the pressure radiator cover

If you have completed the steps above then by now your radiator should be free of dirt and ready to go. Now that yo have successfully flush your radiator at home using a garden hose lets see it if flushing a radiator can cause a problem.

Can flushing a radiator cause problems?

Yes flushing a radiator can cause a problem when it is not done the right way. For example using of dirty water instead of a clean water to flush down the radiator cause cause more harm than good.

If you use a dirty water instead of a clean water to flush radiator you will end up clogging the valves. If the flush isn’t thoroughly to clear all of that out, it can loosen up those things which could clog up the cooling system, including the radiator.

How to check and clean your thermostat’s at home

Apart from the air filter and the radiator, every part of your cooling systems needs to be checked between intervals. Your thermostat can get dirty and start giving you false temperature reading.

This is a good sign either for your householder cooling system neither is it for your car. Just the way you flush a radiator with a garden hose at home you can also clean your thermostat at home.

To check and clean your thermostat follow the guide below to get started

  1. Step 1: Compare its reading with a thermometer. No special tools are need except for the fact that you need another thermostat to compare the readings. You can do this by using a sellotape to tape a glass tube thermometer to a wall couple of inches away from your thermostat.                                                                                                                                                                                                                                   Rap a pice of paper round the thermometer before taping to the wall, this will prevent the thermometer from reading wall temperature. Be sure that neither the thermostat or the thermostat is affected by outside temperature.
  2. Step 2: After placing the the thermometer on the wall, avoid touching it for about 15 minutes. This will enable the mercury to stabilize so as to avoid getting wrong readings.                                                                                                                                   After the said 15 minutes wait, you can now proceed to take measurements. Now compare the temperature reading from both the thermometer and that of the thermostat.
  3. Step 3: The temperature reading at this point should be the same or little to no difference at all. The temperature reading on both the thermostat and the thermometer should be almost the same.                                                                                                                                                                                                                        If there is a difference in temperature above one degree, then you should check your thermostat for dirty or dust inside. To do this you have to remove the plate covering the face of the thermostat.                                                                                                                                                                                                                              Carefully and gently remove the faceplate dust the dirt inside it. If the thermostat has accessible contact points, rub new dollar bill between them to clean these spots.                                                                                                                                            Do not use unapproved cleaning solutions, rough cleaning rag or an emery cloth. If the part you’re trying to clean is coiled, use a soft brush to get at the dirt.
  4. Step 4: If thermostat has a mercury vial inside, use a level to make sure the unit is straight. If a thermostat is not straight, loosen the mounting screws and adjust the thermostat so it becomes is level.
  5. Step 5: After cleaning your thermostat, check it again with the glass thermometer, if the thermostat is still not calibrated properly, it should be inspected by an HVAC professional because that indicates there may be a bigger problem with your heating and air system.

Will coolant flush help overheating?

Yes and No coolant flush will not help overheating, i guess that might be confusing right? Okay the yes coolant flush can help stop overheating only and only if your radiator is clogged and needs flushing.

For instance if you radiator is not blocked but your car keeps overheating it might just be that your cooling system is leaking coolant. Overheating can as well be caused by a blow head gasket, a clogged coolant valve even a loose radiator cap.

So, you have to be sure about what is making you car overheat before you start flushing your radiator with a garden hose. I believe this article should have by now answered you question about how to flush a radiator with a garden hose.

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