Amazon: Radiator flush

[P1800Ray]

I want to put a cleaning solution in the radiator that will de-calcify the channels - any recommendations? Would rather do it in situ but could remove.
Thanks 😄

[142 Guy]

Interesting question.

If the internal contamination is due to hard water deposits (calcification is actually a medical term not exactly applicable to that scaly formation) you would typically use an acidic cleaner. Cleaning vinegar with a 10% acetic solution would be a safe starting place; but, might be rather slow. Diluted muriatic acid solutions will be more aggressive; but, you will have to suss out the dilution rate. Remember, always dilute strong acids by pouring it into water - do not pour water into the acid. Remove the rad, plug the lower opening and fill it with the cleaning solution and then let it work for a while.

Unless you have been using pure tap water or a tap water / antifreeze mix, you will not have hard water scale in the cooling system. Pre mix coolant or concentrated coolant with distilled water will not form the common hard water scale. However, as they age they can oxidize and combine with other contaminants that get into the cooling system to form nifty sludges. To clean sludges you do not want an acid based cleaner. You want something caustic. There are a bunch of caustic based radiator cleaning solutions that are commercially available. I have no advice as to which is best.

In my case, the lower 1/4 of the horizontal tubes in my 140's radiator were solidly plugged mid-way across the radiator. I elected to remove the radiator and take it to a radiator specialist who dumped it in their tank of caustic solution for a soak and then flushed and flow tested it. After that they pressure tested it to check for any pin hole leaks that can appear after you clean off the crap that was plugging those pin holes. I didn't particularly want to deal with using and disposing of caustic solutions which can be rather nasty.

So, first off you need to determine whether you have a hard water scale problem or sludge which will determine the type of cleaner that you need to use.

[Bob Meadows]

Central heating cleaner/descaler works well- used it on various occasions for the 240 & a 65 year old classic:~

Fine with dissimilar metals- leave it in for as long as you can bringing it up to temperature within the above period.
Flush out as normal before adding the antifreeze mix.

(1Ltr goes a long way: Plumbers Merchants will hold stock)
Regards Bob.