6cta aftercoolers

[Dave Eberle]

I have a question about the attached pictures. First I serviced the aftercools per Seaboard recommended procedure. I was in the process of servicing them again and noticed the pitting between the o-ring and end cap in the attached picture. That is my starboard engine. Every thing else looks great, housing and core. What could cause this? Is it safe to put back in boat since it is outside of the 0-ring? I change zincs regularly. The second attached picture is my port engine. It also has a little pitting, but not as much, but the big issue is something messed up the tube ends. On this one the housing and rest of core is in real good shape also. I am thinking maybe part of a zinc broke off and rattled around. A friend down the dock had the same thing happen to him. Can that be repaired, there is a little restriction. Should I just get new cores? The engines are 7 year old factory recons with 1100 hrs and this is the 3rd aftercooler service I performed.
Thanks Dave

Topic

[Rob Schepis]

JB Weld would be good, just a tad harder to work with.

For the peened over tubes—an aluminum rod from the opposite end with a taper point—gently

Early tubes were soldered/furnace brazed—later versions were expanded……. Way better if done right

[Bill Desmarais]

I had the same pitting in my 2008 new ReCon 6BTA coolers after three season (May-Oct). Both after coolers were greased with Alco Metalube @ Seaboard before the engines were shipped to me.
I stay in contact with the new owner. After coolers are fine as far as I know….and I know he would have serviced the coolers every three years since with grease.

Pressure test…no issue IMO

[Dave Eberle]

Rob, thanks for the response, I did not think of Bondo, was thinking of maybe JB Weld. Yes I was thinking of just filling in the pits, groves and fairing smooth. I don’t know if it would even make a difference. With regards to the bent up tubes. How are the tubes attached to the plate, are they rolled, soldered or braised? Have you seen this before and experienced no issues provided there is no leakage? There were no signs of leakage when I removed the core, slid right out just a little black.

[Rob Schepis]

Dave are you thinking of using something along the lines of automotive Bondo? Skim around the ring and then fair it down smooth to where the bondo is only left in the pits and grooves? As long as the core passes a pressure test I would not worry about the bent tube ends that I see in your pic

[Dave Eberle]

Thanks for the response Tony. This might be a stupid question, should I try filling the corrosion and smoothing it out before I reinstall it? What about the core with the banged up tubes?

[Tony Athens]

Cummins aftercoolers cores

What you have posted 100% confirms what I figured out about 5-7 years ago……Who ever makes the current genuine Cummins cores changed the alloy that they use for the upper & lower main ring plates (my engineer in Asia calls them “side plates”).. We did a full material analysis of the SEREK aftercooler core built in the mid-90’s and they were 100% up to par as to what would stand up well in this particular “mixed metal” part in this application..

The alloy they used had about 33-36% zinc.. So at that time, if were to get into making our our own core we decided to up the quality of the alloy 2-3%. as to more copper.

What you are seeing what we are seeing now–A cheaper “brass alloy”with “probably” 5-10+% more zinc than Cummins used to use………………………….It’s the typical “save a buck” way these days..

AS to reusing the core–Lots of Alco Metalube and you should be fine..

Tony

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