Volvo D2-55 Exchanger cleaning

[branko]

After 6 years of exploitation I decide (after checking raw water filter) that on my Volvo D2-55 calcificated exchanger on the raw water side is a reason for higher temperature of cooling water ( 100C at 2600 rpm) and white steam smoke in the exhaust. What is the best way to clean exchanger ( chemical cleaning), what acid and how?

 

[FlorealIII]

Do not use acid ! Normally the outside body of the exchanger is in aluminium ( no need to clean ) , but the exchanger itself is a copper tube and within this is a set of small tubings that you can clean by letting it overnight in caustic soda ( 30 percent of NaOH in water ) . If necessary you can probe the small tubings with a copper stiff electric wire . That's how I cleaned my Bowman last year with succes .

 

[VicS]

If this is a limescale ie calcium carbonate scale then caustic soda won't do much good, it will need an acid descaler. Acid descalers to consider are:-
Fernox DS40 which is based on organic acids. It will be relatively slow acting and will need to be warmed to be really effective. It is designed to descale a complete central heating system over a period of several days.
Fernox DS3 limescale remover which is based on sulphamic acid, a slightly stronger acid than the organic acids in DS40 and therefore faster acting, but again should be used warm.

Read about the Fernox products and take note of their compatibility with various metals that might be in your heat exchanger at http://www.fernox.com/index.php?cccpage=products

Another possibility is a product known as Rydlyme http://www.rydlymemarine.co.uk/ I am not sure what that is but I suspect it is hydrochloric acid based although the pH value quoted is not low enough for it to be that alone. It may well be the fastest acting but they claim it is safe on a variety of metals.

It would perhaps be worth testing a sample of the scale in your heat excahnger with some diute acid, vinegar will do. If it fizzes if confirms that it is a carbonate scale.

 

[boatmike]

Totally agree. These products won't hurt the tube stack. You can often find "kettle descaler" or domestic "limescale cleaner" will work OK too and is easier to obtain.
Very often other crud finds it's way down the tube and can be freed up by poking down the hole. Don't use force though and don't use anything wooden or it will break. A tip is that the end of an old morse cable is often just the right diameter to clear the holes, and the threaded end will often clean the tube innards very well!
If there is a solid blockage though use acid cleaner to clear it. Don't try to drill it out or knock it out. Often though its salt deposits which are soft, or other foreign matter like gravel that is blocking it and you won't need chemicals at all.