Seawater cooling question for old salts

[fletch]

Trying to decide best course of action. I have always had maintenance done per the Cummins specs on my QSB6.7’s i.e. annually vice 250 hours in that I have low hours, by a “trusted provider” who went out of business suddenly, (from what I hear was a mega yacht deal gone sour). So, I decided to do the yearly myself (should have been doing it all along myself). Seawater side questions, not a disaster, but troubling… Replacing engine cooling system zincs, they are gone, pulled one aftercooler, looks OK on the seawater side, but on the exhaust outlet port saw some white deposits. Of course the tube bundle is stuck hard, soaking now in PBBlaster. Pulled one HX endcap, some tubes need a good barnacle buster treatment, looks OK, and have never seen anything operationally, both engine temps track and are dead on with each other within a degree at full load. Oil samples look great, so at least I haven’t gone into a dark place yet. Now the question, should I go conservative and dive into the whole SW circuit, given I could have been running zinc deprived for several months at a time over 5 years, and pull the oil cooler and HX, or am I overly concerned? Also posting this as a lesson learned for newbies, like me, wish I had more knowledge of this potential issue earlier.

 

[PM]

All I can say is that I am glad I am in fresh water..

Learning by doing, The American Way !

pete

 

[RT Firefly]

Greetings,
Mr. f. This is pure peculation, on my part...The white deposits may be unreactive in PB blaster. I'd try soaking in "barnacle buster" AFTER a thorough degreasing (get rid of the PB residue).

Barnacle buster is about 10% phosphoric acid and quite expensive IMO. You can buy concrete etching (Home Despot) phosphoric acid (MUST be diluted to 10%) and get the same results.
After all the white stuff is gone, THEN try PB blaster.

 

[DavidM]

Don't know what you mean by "exhaust outlet port". The aftercooler has intake air on one side and sea water on the other.


But if you really do have white deposits on the air side then the aftercooler leaks and if it gets worse will trash your engine. So remove the core, clean both sides, reassemble with new o-rings and lots of grease. Then pressure test. If the pressure test fails then you will have to replace at least the aluminum shell, preferably the entire aftercooler.


David

 

[fletch]

Thanks, that's where I'm heading I think, by exhaust port I meant there is an inlet and outlet that goes to the turbo, it's on the outlet or downstream side, i.e. downstream of the HX, and seawater, going toward the turbo.

 

[fletch]

Thanks RT, good point, BB is definitely high$$$. Wonder what the markup is on that stuff I just wonder if there are some sort of buffers that are proprietary, that might make it somewhat more benign.

 

[DavidM]

Back a 100 years ago I worked in the chemical cleaning industry, acid cleaning central station power boilers among other industrial equipment. We used hydrochloric acid (HCl, muriatic acid, swimming pool acid, etc) diluted 1:2 with a few tenths of a percent of an amine corrosion inhibitor. The inhibitor reduces the corrosion rate by a hundred fold.

One simple test that we often employed to insure that the inhibitor was properly mixed in was to take a shiny common nail, put it in a beaker with the diluted acid and heat it to about 150 F. If it bubbled there was no inhibitor.

I once tried this with Barnacle Buster. It bubbled.

David

 

[fletch]

Thanks, scary, did chemical cleaning in my early days also, fortunately with Navy we had a very prescribed blend, with actual chemists on staff. Reached out to rydlime, they seemed to be very honest, told me if I used their product, use 1/4 of suggested blend on anything aluminum, i.e. the housing.

 

[RT Firefly]

Greetings,
Mr. f. Buffers? Good grief!!! Do you have ANY idea how long ago I took chemistry? If I recall, some dude named Timothy Leary was in the news...

 

[C lectric]

If yoiu have not already then look up
Seaboard Marine.

www.sbmar.com

they are in Cal. but the owner, Tony Athens has provided a huge amount of info for these engines and a lot about the aftercoolers.
Look it up and read it.

 

[Irish Rambler]

If you want a cheaper safer way to clean it go to the supermarket, buy some 12% white vinegar which will do the trick and not so dangerous.

A litre/quart poured down the toilet at night once a month will keep your toilet exit hoses clean from calcium build up (from your pee).

Shower head calcium build up ? Put some white vinegar in a plastic bag, place the shower head in it, tie the neck with cord and leave overnight, job done !

 

[fletch]

I still don't know what a mole is, other than I have a few in the yard

 

[Woodland Hills]

You can also buy 30% cleaning vinegar to do the job faster.