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Old 08-30-2020, 10:06 PM   #1
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Aftercooler Housing Corrosion - How much is too much?

Onward...

One of my projects this weekend is aftercooler maintenance. This boat is now a freshwater boat, so I wanted to get these components cleaned and serviced for their long life ahead. I think what I found is sort of a mixed news scenario, but I'm not experienced with these matters. BTW Cummins 6CTA 8.3 450s here.

On the positive side, both came off just fine, came apart just fine, and the tubes slid out with no issues - no Kroil, no nothin. Very little clogging of any tubes, as they had been serviced in 2018.

So I THINK I already know the answer to the question about the water side. No, I didn't bring it to a shop or any other pressure test method. But I'm pretty sure that there must be some sort of leak on the water side based on a) the green oxidation on the copper on the air side, and b) the pitting and corrosion on the housing. Photos of the starboard side are included. Port side is similar, but definitely much less pitting. First photo is of the tubes, second two are each side of the housing.

I'm resigned to replacing the core tubes, and happy to do so. Now that I'm in fresh water I have little concern for continued corrosion on that end, and I'm more than willing to do the maintenance every couple years to make sure it's solid. My question is on the housing. Yes there is pitting on the housing, but how much is "too much"? It seems that the seal from the water side comes from the o-ring. It seems like I'm not concerned about water seeping through the pits, because they are on the air side, not the water side. Also, it's aluminum so welding doesn't seem to be the best idea, but is there a way to repair those pits?

Thanks for your inputs. Much appreciated.
BD

PS - I hate to brag, but yesterday I did the starboard side and my wife watched and handed me tools. Today, when I struggled to squeeze myself between the port engine and the water tank, she said "Don't worry about it. I got this." and climbed in, pulled all the hoses, pulled the aftercooler, and disassembled and cleaned the whole thing. She then climbed back in there and installed the whole thing with me doing little more than holding it in place and handing tools.

I couldn't imagine a better partner in this whole endeavor.
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Old 08-30-2020, 11:18 PM   #2
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Old 08-31-2020, 05:21 AM   #3
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I can't really see any corrosion on the o-ring joint and I don't quite understand what you say about not being concerned about the o-rings leaking on the air side. That seal keeps air on the air on the air side and water on the water side. If they leak sea water can get through.

But if you are always going to run in fresh water that is less of a risk. Also the fact that they came apart easily indicates not so much corrosion.

So reassemble with lots of grease on the joints. Then do test it, either with a radiator testing kit you can borrow from the auto parts store or having a radiator shop do it. If it tests ok then you should be fine running in fresh water.

In fresh water service you should be ok doing this again in five years.

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Old 08-31-2020, 06:52 AM   #4
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That corrosion is not necessarily from a sea water leak. When running at higher power, condensation occurs in the air side, and when shut down it pools at the bottom. With water in the bottom, galvanic action pits the aluminum.

Don't worry about pitting on the inside diameter. The oring seals against the bottom of the housing, that flat on the bottom must be in good shape, no pitting. From the photos yours look ok, but hard to tell.

If there is pitting, a machine shop can fly cut the ends, easily done but need a taller than average mill.

All three surfaces that contact the oring must be clean clean clean.

Put it together and pressure test the water side with water under about 30psi. Leave sit under water pressure for a couple hours, if no water shows up on the air side, you are good to go.
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Old 08-31-2020, 07:32 AM   #5
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Thanks Ski, that's where I was going. David, sorry I wasn't more clear.

I was looking at the corrosion on the inside diameter. The flats look good as do the caps, and the o-rings should be seated just fine. I used a considerable amount of grease per Tony A.

I will develop a kit to perform the pressure test. There is only one radiator shop that's less than 100 miles away and they're closed on weekends. I'll just do it myself.

If I can get out of this without having to buy two new aftercoolers, that'll make my day! Thanks again.

BD
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Old 08-31-2020, 10:14 AM   #6
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there are two diameter sizes of O rings, be sire to get the correct size.

I always order my Cummins parts from seaboard marine. They seem more familiar with the marine engine parts than my Cummins dealer.
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Old 08-31-2020, 11:30 AM   #7
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Quote:
Originally Posted by bayview View Post
there are two diameter sizes of O rings, be sire to get the correct size.

I always order my Cummins parts from seaboard marine. They seem more familiar with the marine engine parts than my Cummins dealer.
All of these parts came from sbmar.com. O rings were proper size (identical to old ones).
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Old 08-31-2020, 12:56 PM   #8
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PS - I hate to brag, but yesterday I did the starboard side and my wife watched and handed me tools. Today, when I struggled to squeeze myself between the port engine and the water tank, she said "Don't worry about it. I got this." and climbed in, pulled all the hoses, pulled the aftercooler, and disassembled and cleaned the whole thing. She then climbed back in there and installed the whole thing with me doing little more than holding it in place and handing tools.

I couldn't imagine a better partner in this whole endeavor.
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Old 08-31-2020, 01:26 PM   #9
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I may have said too much!
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Old 08-31-2020, 01:55 PM   #10
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Yep. I have me one of those ladies too. I was fretting about having to squeeze in front of the port engine to change the raw water pump on my 6CTAs. So my little petunia said she would give it a try and climbed in there and did a great job!!! This is her in action....

PS....it is hard to tell by the pics but your aftercoolers look fine to me. Do all the right things and get them pressure tested and enjoy the boat!
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Old 09-01-2020, 11:31 PM   #11
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I'm going to show this thread to my wife. She has a raw water pump to swap out and needs some encouragement.
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Old 09-02-2020, 09:32 AM   #12
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I'm going to show this thread to my wife. She has a raw water pump to swap out and needs some encouragement.
I will admit having owned a BTA, they are a little more compact and difficult to get to. There have been installations that require you to loosen the engine mount to remove the old one. And if you are going through the trouble of changing them, is highly recommend the SMX pump over the OEM Sherwood.
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