Water channels

[Fspp369]

Hello all,
I’m about to start recommissioning/ reinstalling my V12 after about 2 yrs of back of the garage life!
I want to clean out the engine waterways, what solution would anybody recommend. Someone did suggest a citric acid solution….not sure,,!!!
I have no intention of doing a full strip down as the unit was running sweetly.
Any information gratefully received.

[paydase]

I once made a "treatment" with diluted phosphoric acid.
Will never do again, it took numerous flushings to get rid of all the chalky residues coming out.
Not taking account of the risks to obstruct somme of the tiny channels...

[Fspp369]

Oh, there's food for thought.
Thanks..

[abowie]

Take it to a radiator specialist.

They have equipment to power backflush the system, and test it in situ for flow.

Otherwise there are a number of proprietary flushing solutions available.

[Series1 Stu]

Citric acid will help as you are introducing an acid to attack the calcium carbonate (limescale) which is alkaline. It will be a lot more effective if it is used hot. It's just like descaling your kettle although the flaky lumps are more difficult to remove from an engine's waterways.

That said, I would still prefer to take it to a specialist.

Regards

[Fspp369]

I don’t think a Radiator specialist would not be impressed if I turned up with an engine.
I think I can do about 20l/min at 100C if I can get organised… it’s the chemistry that I want to get right.

[mgcjag]

Hi Peter..iv done a few 4.2 engins..removed coreplugs
Removed waterpump/ thermostat and drain plug.. then used a jet wash...it soon flushed out lots of old crud and scale...gaffa tape up any oarts you want to keep dry..Steve

[Fspp369]

I am the proud owner of a V12….1974

[mgcjag]

Hi Peter...yes I know its a S3....I was explaining what iv done on a 6 cylinder engine...not really much difference in jet washing it...Steve

[Fspp369]

[MarekH]

I once made a "treatment" with diluted phosphoric acid.
Will never do again, it took numerous flushings to get rid of all the chalky residues coming out.
Not taking account of the risks to obstruct somme of the tiny channels...

I thought the whole objective was to get rid of all of those chalky residues, so I'd be pleased to have shifted those. They certainly won't have been doing any good left where they were.

Aside from that, using phosphoric acid was probably not the way to go, as this would have attacked all of the hose fittings on the water rails which are made of steel, plus the header tank and the pipes under the shroud ahead of the radiator and the heater return pipe on the left side. Hence citric acid being recommended.

Where possible, I've replaced steel water rails with something non ferrous, e.g.brass or copper or rubber.

kind regards
Marek

[Fspp369]

Perhaps should clarify..engine is on the bench stand.

[mgcjag]

Ideal to wheel outside and jet wash in as many internal areas as you can....you will be supprised what comes out...Steve

[paydase]

I once made a "treatment" with diluted phosphoric acid.
Will never do again, it took numerous flushings to get rid of all the chalky residues coming out.
Not taking account of the risks to obstruct somme of the tiny channels...

I thought the whole objective was to get rid of all of those chalky residues, so I'd be pleased to have shifted those. They certainly won't have been doing any good left where they were.

Aside from that, using phosphoric acid was probably not the way to go, as this would have attacked all of the hose fittings on the water rails which are made of steel, plus the header tank and the pipes under the shroud ahead of the radiator and the heater return pipe on the left side. Hence citric acid being recommended.

Where possible, I've replaced steel water rails with something non ferrous, e.g.brass or copper or rubber.

kind regards
Marek

Marek,
Actually I was surprised by how much calcium and other salts were released and of the numerous operations that were necessary to clear the outcoming flushing water. Maybe also because I did not use a pressurised flushing and it was difficult to clean the lower parts of the circuit (e.g. radiator bottom).
When I saw that, I feared that this crud could block some of the smaller passages in the circuit but at the end of the process it was ok.

Concerning the choice of the acid, I had explored many of the possible options.
Of course excluding strong acids such as hydrochloric, even diluted.
But also acetic (vinegar) or citric, as they attack steel more than phosphoric because phosphoric produces a passivating layer on steel (a specificity) while other acids don't and their corrosion continues.
Actually, most of the solutions offered by commercial brands to clean cooling circuits basically contain phosphoric acid plus a number of wetting agents and some more stuff.
What I did was to dilute phosphoric at a concentration known to be suitable (don't remember, maybe 1/10) and also took care of rinsing numerous times shortly after with water and then 50/50 glycol/demineralised water.
At the end of the day, I believe that most of the chalky material was removed and that the rest has settled down again.
Btw, since I did that several years ago, no indication of any corrosion in the rad, header tank or pipes.

[abowie]

I don’t think a Radiator specialist would not be impressed if I turned up with an engine.

It'd probably be easier for them than doing it in situ.

Although if you can do 20l/min at 100C that's probably as good as they can.