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Old 11-06-2015, 06:22 PM   #1
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Bowman Air Charge Cooler: Need help reassembling

It all started out so innocently. I removed the Bowman air charge cooler (intercooler) to take home and clean. The plan was just to soak it in Barnacle Buster to dissolve the deposits. Then I came across this thread at ybw.com that made it seem easy to disassemble. Now I have mess on my hands and need some advice.

It looks similar to this picture without the TAD:

I used a lot of muscle to "tap" the copper core (matrix) out of the cast iron housing. The iron housing had enormous amounts of built up scale that bound the core to the housing. It's like this hard black crumbly crud that grew from the sides of the housing into the core. The crud is jet-black and makes a massive mess like chimney soot. I worked the core back and forth using a variety of solvents and chemicals to loosen the crud. I finally got the core out with a 2X4 and a mallet. I started being super gentle but after a while it just took a lot of pounding.

Once the core was out I discovered about 3/16" of the crud coating the inside of the housing. I was able to blast most of it away with a pressure washer. I soaked the copper tube core in vinegar and alternated between steam cleaning, pressure washing and light bead blasting.

Is it likely I damaged the core with all the banging? It looks like it's in good shape but there's so much I can't see. Is it a bad idea to add some more tin to the ends using a mapp gas torch?

Can I wire-wheel the inside of the iron housing, then paint the inside with epoxy for continued corrosion resistance?

Do I have to replace the two rubber O rings or can I reuse the originals with some non-hardening sealant like Hylomar?

Is there some kind of sealant I should use on the ends of the core when I put it back in? I was thinking about coating the edges with silicone RTV or some other liquid gasket material.

Thanks,
Robert
1977 Perkins T6.354
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Old 11-06-2015, 08:13 PM   #2
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You do have a mess on your hands. That after cooler looks different from ones on modern Cummins and Yanmar engines. Those have the water inside the tubes and the air outside. Yours looks opposite. That is probably why the shell is cast iron rather than aluminum like the others.

Clean up the core by soaking in Barnacle Buster, Rydlime, etc. to remove the scale. Make sure that the tubes are open before doing this. If any are closed up with scale, rod them out so that the acid can get through. But most of the scale is probably on the outside of the tubes where the raw water flows.

Clean the shell up by water blasting and then soaking in BB, etc . When both shell and core are squeaky clean then see if the core will slide back in. it needs to slip in easily with little pounding.

You won't know if you have damaged the core until you have put it back together WITH NEW GASKETS and lots of water proof grease on the end and sides to let it slide in easily and limit future corrosion. Then you have to pressure test it to know if it leaks. You can borrow a radiator test kit from your auto parts store. Pressure the water side up and look for leaks into the air side.

I can't really comment about soldering the tubes. The tubes should be rolled into the tube sheet which seals it, not with solder.

The proof is in the pressure testing, in any case.

David
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Old 11-06-2015, 08:39 PM   #3
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Thanks - for the pressure testing what's the recommended PSI? We have water pressure here that's 120psi and 80psi. I was thinking I'd cap one end and attach the other to the garden hose. I can't imagine the water pressure gets anywhere near that when running.

I thought the design seemed backwards, with the air running through the tubes. Also seems like a plastic housing would be better.

Thanks,
RR
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Old 11-06-2015, 09:03 PM   #4
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don't use silicone
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Old 11-06-2015, 09:47 PM   #5
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whats wrong with silicone?
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Old 11-06-2015, 11:00 PM   #6
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Take our word for it, don't use silicone.

Do use new gaskets/ O-rings. Pressure test it first before you start smearing sealant around.

By asking about adding solder to the tube bundle I assume what you are seeing is that the tubes are soldered/braised to the separation plates? If so I would not add any solder till you pressure test the cooler. You could just pressure test the tube bundle without reassembling the whole cooler.

Baby steps. No need to unintentionaly open any more cans of worms.
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Old 11-07-2015, 04:23 AM   #7
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I believe you.

So I'm wondering why and came aross https://mercedessource.com/problems/...sket-adhesives

What do people think about Hylomar, or https://mercedessource.com/store/ana...maker-the-best
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Old 11-07-2015, 09:44 AM   #8
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Here is an article on cleaning and reassembly of the Cummins air cooler: Aftercooler Maintenance - Cummins

Even though the Cummins housing is aluminum and the flow is different, the principles are the same. You can use Alco Metalube which you can buy from Tony's shop or any waterproof marine grease. Make sure that the sealing surfaces are good- no tool marks or gouges on them.

The grease doesn't seal but it makes the parts go together smoothly and blocks future corrosion and makes future disassembly easier with little or no pounding.

I would test at 15-30 psi, not the 80-120 psi of your water system. That is why I suggested the radiator test kit which comes with a hand pump.

David
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Old 11-07-2015, 03:01 PM   #9
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If your housing is cast iron like my original was don't leave it lying around too long. It will corrode badly at least mine did from the humidity in my basement in the winter with the furnace keeping it fairly dry. It was the raw water nipples that disintegrated. It was a bear to repair.
I think 30 psi would be plenty to test for leaks.
PS I had to use a 20 ton screw press to get my core out of the housing. Mine was packed full of mud as the PO spent most of his time idling at the dock with the keel in the muck
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Old 11-07-2015, 03:10 PM   #10
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I wire-wheeled the inside of the cast iron housing, one of the nipples had significant corrosion and it was disheartening to watch it disappear under the wirewheel. After getting down to solid metal all over I coated everything with epoxy. You could tell is soaked down into the pores in the iron.

I want to modify the drain plug to add a small pencil zinc. Would this cause any galvanic issues since it's cast iron + copper + salt water?

Thanks,
RR
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Old 11-07-2015, 05:37 PM   #11
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A zinc will certainly help with water side corrosion. Zinc is the highest (or lowest, can't remember which) on the galvanic scale, iron is lower and copper is lower still. So a zinc will protect both iron and copper.

David
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