Dissolving old coolant without dissolving the radiator?

[ChemicalChaos]

Got a question from a buddy of mine today that has me stumped, so I wonder if you guys and gals might be able to help please?

He is restoring a vintage car and the radiator is totally blocked with solid crystallised coolant. Apparently the type of coolant, once solidified due to lack of flow, becomes impossible to flush out with water as it is not longer soluble.
He says that any "chemical agent" strong enough to dissolve the crystals will also attack and destroy the tin and lead alloy (silver solder) brazing holding the radiator together. I view that as a challenge, as I think there must be something to attack crystals of organic antifreeze/ionic salt buffer without going after the metal.

Having done some research, the particular coolant composition (AL-3) appears to be:

Ethanediol (antifreeze)

Triethanolammonium Orthophosphate (buffer)

Sodium Mercaptobenzothiazole (corrosion inhibitor and dye) - I'm aware this last one is also pretty nasty

Would I be right in thinking that the salts would be the main culprits in precipitating out as insoluble crystals?

Can you think of anything please that would break down these compounds into an aqueous solution without reacting with the metals?

Thanks!

[ChemicalChaos]

I don't profess to be a world expert in my field!

I can only assume that the salt crystal deposition is much like hard water deposits in a kettle, where dissolved ions precipitate out into insoluble solids

[mike_knott]

anonymous said:

[redacted]

This.

How did the antifreeze originally get to be part of the solution if it is insoluble?

Try pouring hot water onto it to confirm that it is definitely insoluble. If it is, a replacement radiator will potentially save him days of trying to find an appropriate solvent.

Mike...

[ChemicalChaos]

How does calcium carbonate in stalactites originally get to be part of the solution of dripping water if it now forms bits of rock deposits?
From my understanding, the car before restoration constantly overheated, suggesting the good coolant inside was reaching boiling temperature without dissolving the crystals.

[jet_noise]

Isn't this more likely to be corrosion deposits or limescale?
Anyway try vinegar - will dissolve alkaline things, or sodium bicarbonate (baking soda) - will dissolve acidic things. Both relatively mild. I wouldn't want either being pumped around an engine and have no idea whether they attack rubber. Even vinegar will attack copper but maybe not enough to kill it. Do you feel lucky?

I would say, however, that this is rather pointless. There are many radiator services who will take your old rad and build a new one. A copy, an enhancement or a restoration replacing only, say, the blocked cores while retaining the "tank" bits,

regards,
Jet

[TooMany2cvs]

Think I'd start without chemicals - simply by finding a big enough metal tray to sit the rad in, totally submerged and full, then putting it on a camping stove and heating it. Take it out, agitate it, flush it, repeat.

I suspect you'll quite quickly find it breaking down and claggy bits coming out.

If not, then - soddit - recore it. It's probably fairly shagged anyway.

[Einion Yrth]

Think outside the box, dissolve the radiator and use the coolant to form a mould for a new one.

Sorry.

[ikarl]

Try coca-cola.....nasty stuff

[julianm]

Ammonia solution might be worth a try - maybe not .880 concentration but from a hardware shop you can get `cloudy ammmonia` which is pretty conc. - this shouldn`t go for any metallic bits but could hopefully take up some of the solids. If you can scrape a bit of gunge out have mini experiment in a shot glass.Take eye protection seriously if you have a go.
I wonder if some of the gunge is actually old `stop leak` stuff, which is going to be a pain to shift?

[Alias218]

Mr Muscle Bathroom Cleaner. What that stuff can't dissolve isn't worth thinking about.

[Simpo Two]

Nitromors and horseradish sauce.

[RizzoTheRat]

Alias218 said:

Mr Muscle Bathroom Cleaner. What that stuff can't dissolve isn't worth thinking about.

I actually used Mr Muscle oven cleaner when I stripped my bike engine, it made a lovely job of cleaning up the pistons

[blitzracing]

Why make life difficult when someone else has done the donkey work- there are lots of commercial products to do this. Ive used the Holts 2 parts rad flush and it works pretty well- just poured it in with boiling water and left to soak for a while.