QCB 5.9 Heat exchamgers

[Marc Smoorenburg]

Hello,
I have a Sea Ray boat with Cummins QSB 5.9 engines. 425hp. I noticed that there was some corrosion? on the side heat exchangers on both sides, but only at 1 end. Refer to photos..
Can someone please tell me what is happening here?
There is no fluid leaking at the moment, but would like to resolve this issue before it becomes larger.
Also, I know I’m asking alot, but possible remedy and parts required also would help heaps. If it’s an easy fix, I will attempt it myself.
Thanks guys,

Marc

Topic

[Marc Smoorenburg]

Hi Rob,
To answer your question, NO. not any real reliable service history. I have owned the boat for 14 mths and had a Cummins service 7 mths ago. Incl oils, filters, zincs.
Now I am calling my mechanic, & those coolers etc will be on the top of my list.
Thanks

[Rob Schepis]

No, that is highly unlikely. They need to be removed for proper servicing which includes cleaning with an acidic solution, pressure testing, cleanup and touchup the “green” painted areas, and new gasket kits and a zinc. And be sure the end caps have not been flattened from over-tightening, etc. which is what the article is what that topic was about that I attached the link above.

What about all the other “coolers” ?? – you did not answer my question about maintenance history?

Especially the aftercooler – here’s another link

https://www.sbmar.com/articles/cummins-marine-aftercooler-maintenance/

[Marc Smoorenburg]

Thanks Rob, so am I right , the best fix is to replace the heat exchangers?

[Rob Schepis]

Call it oxidation, corrosion, “alloy rust”, whatever, but what it really is is a sign that MARINE AGE is winning the battle in a big way. Is there any reliable service history on your seawater side components? Cooling pump > Fuel Cooler > Aftercooler > Gear Cooler > Heat Exchanger…….

Here’s one topic that can help you:

Heat Exchanger Flat End Cap Fix

[Author]

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