Hardcore cooling system flush

[tonydca]

Sorry this is a re-post from the end of a recent thread of mine, but I wanted to start it off as a new topic...

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An issue that seems to crop up frequently is calcified/petrified cooling systems. On the assumption that the cooling channels in the engine will be as clogged as the rad/hoses, just re-coring and swapping tubes won't necessarily cure overheating ills.

One thing that has crossed my mind (I've never tried it before) would be to follow up a re-rad/re-piping with a generous engine flushing with a de-calcification solution like CLR or the like.

I don't know if there are any of the engine internals that would dissolve along with the calcium , so interested if anyone here has tried such madness on their baby with good or bad results.

[BCDelica]

Of our two old Delica's, I did try the 4L can of CLR and it didn't remove much. But the follow up strong acid flush, not meaning some preastone or CT kit but a large amount of acid, removed a good amount of grunge leaving the empty rad looking spotless under examination. Well the junk really sloshed out after the first 10-15 min acid run; but with strong acid flushes you should rinse a couple of times with water, one time with a box of baking soda as a neutralizer, and for safety reasons change out the rad hoses.

An environmentally safer way is to obtain 2-3 pounds of critic acid and use that for an acid flush on the rad system. Previously to using this method I would remove a rad and take to a rad shop for through cleaning.

Disclaimer: this method was shown to me be a mechanic like 20 years ago and it is very important to not leave the strong acid solution in for to long or damage could result. Also a strong acid solution, or even CLR (acid mixture), used may hasten the failure of sketchy, close to failing, water pump seals.