By December 28, 2012 2 Comments Read More →

Flush Radiator

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Reader Question

Austin, I see you are not a big fan of flushing car radiators so can you please tell me why you feel that way? I want to flush out the radiator in my Honda but after reading your site I am wondering if that is still a good idea for me to do.


Hi Pam

Thanks for your great question! First off, I am not opposed to “flushing a radiator” as long as it’s for the right reasons. Flushing, either with a garden hose stuffed inside the radiator neck, or using the latest and greatest coolant flushing machine at your local oil change place…just flushes out the surface rust and crud that has build up in the cooling system.

The bulk of the rust, mineral deposits and junk will be embedded deep at the bottom of the radiator which can not be “flushed out”. A new radiator or a professional radiator repair shop that can dissemble your radiator and “boil” out the junk is what really needs to happen.

Now, with that said. If you just want to flush out the old coolant and install new fresh coolant AND you are not experiencing any overheating type issues then YES, feel free to flush out the radiator as you see fit. Replacing the coolant every 60,000-100K miles is a great idea and should be part of regular maintenance.

If you ARE experiencing an overheating issue (especially at freeway speeds where a radiator restriction will show up) I would not bother with flushing and replace the radiator if it is indeed restricted.

If you can see red/orange rust at the top of the radiator then think about what the bottom must look like where it settles and accumulates over the years. Yuk!

Flushing is like brushing your teeth. You brush to help prevent cavities from forming, but if you already have a cavity brushing will not repair that tooth…its too late.

Posted in: Over Heating


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2 Comments on "Flush Radiator"

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  1. Austin Davis says:

    The first thing I would do if you were in my shop is get a cooling system pressure test to help locate the coolant leak. I would also make sure the electric cooling fans are cycling on and off at idle as the engine warms up, they should. I would also check the radiator for a restriction at the bottom…which can not be “flushed out” but requires radiator replacement.

    Did you watch my overheating video, it might help narrow things down for you.

  2. Migue says:

    I have a 2002 dodge stratus and it over heats at idle only after driving for 10 miles I have no visual antifreeze leaks ad no build up tempture drops when car is in motion fans come on at regular speed and high speed automatically but o seem to have a loss of compression on power but no check engine light I’m confused any suggestions? O ya an im lossing antifreeze but no white smoke ???

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