6BTDA Cummins Aftercooler Condition

[Kevin Spellman]

Our new to us 1997 Bayliner 4788 has twin 330’s with roughly 1300 hours. We know the boat sat for a year (yes, I know) and don’t have any maintenance records from either of the previous owners. We had a technician doing some work and he mentioned the aftercoolers should be looked at. In looking at them both P & S housings look a bit rough and I am wondering if I should just go ahead and replace the whole assembly ($ Ouch!)? Pics below, can these be cleaned up and actually seal with proper O rings?

Topic

[Corey Schmidt]

Only way to really find out the condition of the aftercooler is to remove it from the engine, take the core out and post some really good pictures…

[Rob Schepis]

No doubt that the very poor ambient conditions did considerable damage to probably way more than just the aftercoolers in this engine room. The condition of the air horn to the left in this photo speaks for that. But a big player in my “conclusion” of these being beyond service is that the cap hardware looks untouched for quite some time evident by the continuous paint between the bolt and the cap that is flaking off. Not to mention that discolored brass zinc cup with rounded off edges. All the pieces add up to a puzzle that is not looking good…..

[David Marchand]

Actually those pics show external rust and corrosion to me. Maybe due to salt water spray from some leak or just a high humidity engine room. So they may not represent what is inside.

So pull one off, remove then end cap and look at the shell to tube sheet seal that separates sea water from air. If it is also corroded then Rob is right- high probability that the cores are frozen in place. But you might get lucky!

David

[Rob Schepis]

There is no way to know for sure until they are removed from the engine and put on the bench. 99.99% the cores will not come out and the aluminum housing is corroded beyond any chance of getting an o-ring to seal. I’d put ALL of my money on them being totally shot…

[Author]

Replies