Aftercooler Service and test

[Robert Towsley]

I have 2002 370 BTA’s and have not personally serviced them before. I’ve read many of your articles (thank you) and removed aftercoolers, then cores and tried to clean them.  I had some trouble removing the starboard one.  I used kroil, a wood block and rubber mallet, which resulted in some deformation of the top of a few tubes. The port one was relatively easy to remove, but as you can see was somewhat damaged at the ends from previous removals and shows some signs of corrosion. I then cleaned them with several cans of brake cleaner, soaked them in 1:3 mix of simple green, then rinsed well in warm water.

A few questions:

I plan to own this boat for a while, does either look beyond long term use?

They still don’t look particularly clean to me and show some residue. Is this what I should expect? Should I take them to a  local radiator shop (if so, any special instructions)?  

Do you recommend that I pressure test each assembled aftercooler by closing both inlet and outlets and running house water into a zinc location? If so, to 30-40 psi?

I guess this test would also test the housing, which does have a good amount of corrision,  but looks like the top surface is flat where the o-rings bear against.

Thanks – Any thoughts would help?

 

 

Topic

[Rob Schepis]

Sounds like you got it.  The flats on the housing where the o-ring gets crushed by the cap is a sealing surface as is the sidewall of the core end.  And the bevel inside the cap as well, clean that real good with a 3m pad or such.

[Robert Towsley]

Excellent.  

Being suspicious of the core because of the residue makes sense to me (as does the delta for the pressure). I will look into the ultrasonic cleaning and also call you to see about sending them in.  

Also, If I am thinking about this right then corrosion on the inside of the housings doesn’t matter much (until it starts separating the gap between the core and the housing) for keeping the air pressure because the air seal is on the 0-ring on top/bottom and the caps, and the water seal is only between the core ends and the cap. If that is right,  I now have a much better understanding of what is going on. 

Thanks.

[Rob Schepis]

Air side fins look “green”, I wonder if they were cleaned with an acid based cleaner at some point? Is there still residue on the fins and crud between them?  If so maybe an ultrasonic cleaning would do them better if you could find locally.  Or you could send them to Seaboard where the cores could be pressure tested as well Yes, pressure test the assembly.  You can water pressure test the seawater side and verify she holds pressure and no visible water appears on the air side.  But no need to go that high, 25psi would be fine.   With a strong raw water pump (new impeller), you might see 15-20 PSI in neutral at 3000 RPM and under load at 2800, maybe a 5-10 PSI max delta due to boost pressure on the air side combatting the pump pressure on the seawater side.  It’s all about the DELTA between the two..  Fit a pressure gauge on a zinc port so you can see the pressure.  Here’s my rig..

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