Flushing Your Block & Rads Clean

Posted: February 26, 2011 in How To & Misc
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So you have all your brand new parts, and you are anxious to hook them all up.  Unfortunately, many parts particularly radiators come with flux and other nasty bits of gunk inside that can only be removed by flushing.  There have been a lot of various methods people use, some with chemicals, and I figured I’d share my particular method.

I use a very basic faucet flush system.  I can’t tell you the part number, but I can tell you there are likely some similar options out there to make your faucet a flushing system.  This allows you to use cold/hot water from your faucet to run a continuous stream of water through your parts flushing your parts clean.  The following photo should give you a rough idea, it’s a very simple gasket hosebarb I found that very cleanly threads into my second bathroom sink.  I’m not sure what the threading is, but these seem to run standard sizes.  I just tried one I saw at the plumbing store and it was a perfect match.

To flush parts I simply follow a two directional process.  This includes flushing with hot water one direction, then switching the part port and doing a reverse flush.  For stubborn parts you could run the water for a lengthy time, perhaps 30 minutes if needed.  This works well, but BE CAREFUL.  Household water pressure can exceed 50psi, this is more than enough pressure to cause permanent damage to radiators or blocks if you blocked the outlet port or ran the flow up too high.  I personally have never had a problem with this, but I have heard at least one story where someone blocked the outlet port on a radiator and bulged the flat tubes out round.  Respect the pressure and you’ll be fine.

Here is a simple example of flushing a block, I just grabbed an old block from my parts bin, but the same process applies to any blocks or radiators.  Flush one direction, switch the other direction.  Many people also take blocks apart and rinse and scrub with a toothbrush which is fine as well, just make sure you put it all back together correctly.

Turn the hot and cold to a comfortable temperature and let water do the work..

The final step is to drain the tap water, then flush the bits of tapwater out with distilled.  I would also be a bit cautious about “HOT” tap water.  Depending on your water heater, the water temperature could potentially be damaging to plastic parts.  You might want to keep an eye on water temperature and take it easy on the plastic bits.

Acetal for example is rated to 80C/180F, but I’m not sure what glued joints can handle.  I would assume in general you can use fairly hot water for radiators or other all metal construction, but you should dial it down for plastics, and only use warm water for anything with a glued joint.

Hope this helps.




Videos by other watercoolers:

The Odai from xtremesystems showing us the problem at hand in his radiator:


And West Coast Mods Filter Method is another way:

  1. Ceadderman says:

    You can do the same thing that the WCMods fush kit handles for a tad less but it’s a helluva Idea. 🙂

  2. norman power says:

    Dear Martin, Been seeing some info about the new 180 mm radiators by magicool and 200 mm radiators by others but no test data about them. Also wondering how they stack up against other radiators . Would also like to know what their equivelents in 120mm x2 and x 3 fan versions verses 180 single and double fan and 200 mm radiators. Thanks for any insight into these new radiators

    • Martinm210 says:

      Good questions and not much info to look at that is apples to apples. The only way you could really understand is to test each with the same exact fans using some sort of adapter. Then there is the data gap in how good or poor the larger fan sizes work. I do know that 140mm fans produce more flow per RPM but they also produce more noise per RPM and produce basically the same noise per CFM. In the end I found that really good 120mm fans on 140mm radiators did better than the best of 140mm fans.

      As an estimate I would just use the frontal area as a comparison, but keep in mind the fan options. We have some really good 120mm fan options and large sizes are much more limted with little to no data on the 180+mm fans. In the end, you will have to guess and if you are happy..thats all that matters..:)

      • nesto says:

        Would using a garden hose purely to flush be a bad idea? It doesn’t seem so bad if you don’t put the pressure too high. My sinks don’t have room for adapters of any sort, but I can easily get a female hose to barb adapter.