Lower Aftercooler Zinc All Gone

[Steve]

Did an annual service today which included replacing the three zincs in our qsb 5.9 425hp. The top zinc of the aftercooler and the heat exchanger zinc looked fine. Attached is a picture of the zinc on the bottom of the aftercoler. This is after 11 months. About 140 hours worth.

What is going on here?

Thanks
Steve

Topic

[Steve]

Roger that……..I’ll add the more regular replacements into the maintenance schedule. I’m relieved it doesn’t appear (at this point anyhow) to be indicitative of a more serious problem and I’ll keep a close eye on it.
Thank You
Steve

[Rob Schepis]

If all else seems as normal I would just put it on a tighter replacement interval and go from there…

I do engine zincs pre-launch and then again mid-season, they always come out not needing replacement but get replaced anyway as it’s easier than dealing with end of life zincs that want to be stuck, or break off, etc. and it’s also a good reason to inspected everything on all sides of the engine carefully, cleanm and spray as needed, and double check all hose connections with a nutdriver in hand…

[Tony Athens]

The bottom zinc in the aftercooler always goes away quicker–Sometimes 3;1..

Tony

[Steve]

Sir,
I last replaced the zincs and caps in May 2017. The zincs were still whole and showed pretty minor wear. The cap is still attached in the picture. The hull zinc wear has been normal as well. Nothing unusual.

I cant understand how the bottom zinc is completely eaten away but the other two seem normal. Granted the bottom one constantly sits in water but I’ve never seen any zinc so totally destroyed….

I’ll be checking it every two months so see what develops but I’d sure appreciate any theories you have as to what may have happened and what I need to pay special attention to.

Thank You
Steve

[Rob Schepis]

Is this a new development in that you have changed zincs at this same interval before and that zinc was not totally spent? The rust color is puzzling. Is the brass cap attacked as well? Do you know how the hull zincs are holding up?

[Author]

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