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How To Flush a Car Radiator System

This article will go through what you need to do when you want to flush your car’s radiator. Flushing a radiator is a process of draining it with the aim of not only removing any sediment that has built up inside but also lowering ground levels and water pressure. Flushing a radiator should be done every two years in order to give the system enough time to cool down, purge air, and enable it to circulate more water before exposing it again to high heat. 

In this post, I will provide some tips on what you need in order for this process, how much maintenance your system needs, and why flushing should be done every two years.

The following is what you should have to flush a radiator:

  1. Radiator bleed valve – This will be located near the bottom of your radiator stop leak and is used at the start of the flush in order to release air that has built up inside. This can be purchased for around $20 or found free at your local auto parts store.
  1. A bucket- This will be used to drain the radiator and will allow you to not only empty it but also to inspect inside should you have any concerns.
  1. Teflon tape- This is used in order to seal the bleed valve so that no air can escape while you are flushing your system.
  1. Brake cleaner – These products are used in order to clean any residue sediment out of your system.
  1. Radiator filler/bleed tool- This will be used in order to fill your radiator once you have flushed it.
How To Flush a Car Radiator System
How To Flush a Car Radiator System

Inspect For Debris

Next, you will want to remove the radiator caps from both sides of your car and check for any debris that might have been collected in them as well. If necessary, use a brush or pipe cleaner in order to clean them out. Then tighten down these caps so they cannot leak while pumping air out of your system.

Fill Radiator With Water

After this, you will want to fill your radiator with the recommended amount of water. While doing this you will want to clean out any old fuel from your lines, the filler tube, and any other areas that might have water in them. This is where the brake cleaner comes into play in order to clean these areas out.

Bleed Radiator

After filling up your radiator you will want to bleed both sides of your car separately. Bleed the rear first so that it can bleed a little bit more than the front before you add more water, then begin back on both sides again in order to get rid of air that has been built up inside over time. 

Top Off Radiator

Once you have finished flushing your system you will want to top off the radiator with water to the recommended level. This amount varies depending on the size of your radiator but it should be somewhere between the manufacturer’s fill line and half of that mark. While doing this make sure all caps are tight on both sides before running through a check sheet that will ensure you have not forgotten any areas. 

Check For Leaks

Then check for any leaks at all connections, connections to pipes, oil pressure lines, and so on. If there is a leak then you may want to take apart the pipe in order to see where it is coming from and what caused it. If in doubt then you can always just reinstall the original cap.

Once your radiator is fully flushed you will want to begin checking for leaks at the end of pipes, or even at the radiator itself. This is where all of your patience will come into play, in order to find all leaks it is best to just follow the car’s plumbing lines and connectors that have been laid out on paper and marked. Use a marker to write down any leaks on this system as well as any other areas where water may be seeping out. This can be done through a funnel or by spraying a spray bottle with water until it begins dripping then marking down where it is coming from as well as what caused it.

Check Valves As Well

While checking for leaks make sure that you check the valves as well. The valves are what will control water flow in your radiator after the system has been flushed and they need to be completely tightened down or they can become air leaks or even leak completely. 

If you find a leak then you should either clean it thoroughly with some rubbing alcohol in order to remove oil, dirt, and any other residue that might have built up after years of use. 

Repairing Leaks

In order to repair a leak, it is best to replace the part itself. Inside the radiator, you will find a series of valves that you can service by simply removing the car’s thermostat and thermostat housing, which should be located in your engine bay. With these parts removed you will find a radiator overflow outlet which is where all of your water will flow into. Underneath this is what we need to replace, in order to do this we need to remove the plastic caps at both ends of the radiator overflow valve. Then with our new gasket leak-proofed replace these parts and tighten down all connections while checking for leaks at any other connections as well.

The intake lines that connect from your tank to your radiator are also commonly prone to leak. In order to replace these take your intake pipe off, this can be done by using a wrench to remove the bolt holding it down. Then with the old part off slowly unscrew the new one, be sure not to get any dirt or residue from doing so inside of the tank. Then replace it and tighten down all connections while checking for leaks at any other connections as well.

If you still have any issues after this then check for any broken or disconnected tools and make sure all bolts are tight, especially check that your radiator stop leak cap is tight as well because if this isn’t then your water can leak out onto your engine plugs.

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