Cleaning coolant side of heat exchanger

[HKTim]

I just had to replace the heat exchangers on my one year old yanmar JH57 engines. The engines have about 300 hours. On inspection, the spaces between the copper pipes in the heat exchanger were "gummed" up. The coolant is supposed to flow around these pipes freely. But that was not happening at all. Doing many many flushes with distilled water had no effect. So wondering if there is something more aggressive to flush thru the coolant system that will not do any harm to the rest of the heat exchanger or engine?

Btw, the cause was from mixing different types coolant that was done during delivery trip form South Africa.

Thanks


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[Reefmagnet]

A short soak in 20% hydrochloric acid solution works. Neat vinegar would probably work too, but would need a much longer soak.

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[HKTim]

Thanks. I assume you'd want to remove the heat exchanger to do this or can I just fill the coolant system up and let it soak awhile. Then flush out with water?


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[savoir]

Depending on where you are hydrochloric acid might be labeled " muriatic acid ". It will certainly do the job with around a 20 - 30 minute soak. Rinse it well in water when you are done with soaking.

[Reefmagnet]

Originally Posted by HKTim

Thanks. I assume you'd want to remove the heat exchanger to do this or can I just fill the coolant system up and let it soak awhile. Then flush out with water?

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Yes, remove to clean. A short length of 3" or 4" plastic drain pipe with an end cap glued on makes a perfect soaking container.

[Badsanta]

I'd also be worried about clogged cooling passageways in the engine it's self.

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[foufou]

I have heard baking soda and water recommended for cleaning radiators, fuel tanks. Pretty benign stuff

[tkeithlu]

Baking soda is not likely to help in this case, because the deposits are likely to be calcium based. If you have trouble finding muriatic/hyrochloric acid, look in the patio/swimming pool section - it reacts with the calcium compounds found in cement and grout for tile.

[DeborahLee]

A good auto coolant flush should take care of problem and clean the cooling passages in the engine also.

[elcappytan]

I've used 50-50 water and white vinegar. Soaked over night, flushed and it's worked fine. I'm kinda afraid to use acid unless it's really really bad.

[RichandHelen]

My engine guy has become a proponent of cleaning the exchanger in an ultrasonic cleaner. This after a whole career soaking them in acid. His feeling is that you may get away with acid a few times but, long term, it eats away the metal. The ultrasonic is benign.

[a64pilot]

Originally Posted by DeborahLee

A good auto coolant flush should take care of problem and clean the cooling passages in the engine also.

This, as he asked for coolant side cleaning, and said one yr old engine.

I took my Yanmar Heat Ex out to clean it, filled a 5 gl bucket with about a 50% mix of Muratic acid, when I put the tubes in to clean them, it boiled like crazy.
I thought Wow, I didn't know I had much growth in there, it looked pretty clean, then the mix began to heat and the boiling got real vigorous. Then I thought, I know there couldn't have been that much growth, what is going on and removed it.
When I got a hard look at the tubes, it became apparent that the outside covering of the tubes was zinc, and I thought OK, that's why there are no zincs in my raw water cooling side

Mine is a 30 yr old 4-JHE, your results may vary of course, but overly aggressive cleaning may not be a good thing, especially on a one yr old engine.

I installed one of these in my hose that goes to the water heater, it is essentially the same as the heater hose on an automobile.
http://prestone.com/enmx/node/461
then connect a water hose and let it run with the engine drains and radiator cap off, water will flow through the engine and out all the drains, let the water run until clear, close drains and run engine until hot, then drain, if water drains out clear, your done. Fill with antifreeze and go, if it is not clear, repeat until it is, if there is a lot of rust etc., remove the thermostat and replace the cooling neck and hose and that will allow water to flow through the engine un-impeded, do not operate the engine with thermostat removed for long.

[a64pilot]

Google DexCool flush, I'm not saying Dexcool was added, but it sure sounds similar.
Dexcool is / was a GM product that if used correctly really was a good coolant, trouble is people don't maintain their cars and it began to have issue, and if regular coolant was added, it formed a sludge, like what you have.
There are some different way to clean it, like a citrius acid based radiator flush that isn't harmful, and apparently using machine dish washing detergent, machine as it does not suds up, I have never used dish washing detergent for this, but it sounds logical, I know it is a good bilge cleaner as it does not suds up.

[Lepke]

I've been using Rydlyme for a long time, usually on the salt side. But when trouble shooting heating problems on a twin engine setup, one that had just been "flushed" by a boatyard, I tried Rydlyme on the fresh side. It solved the problem and the solution came out looking very rusty. I assume it dissolved rust the modern day caustic cleaner didn't.
Since then I have used it on both sides. I circulate the salt side cold, but have gone to idling the engines when doing the fresh side so I don't have to remove the thermostats. It's stated to be used in temps between 0° - 180°F.
The caustic cleaners were much better 25 or so years ago. I assume it was the EPA that screwed that up, too.