Failed after cooler core

[dave carey]

Twin QSB 5.9, 380 hp.  I ran my boat down the east coast to Florida.  Near the end of the trip, the starboard engine exhaust showed black smoke above 1800 rpm.  Assuming it was a rich condition, I cleaned and replaced the air sep filter and oil separator filter, drain and piping, checked the turbo etc. no improvement.  I finally pulled the after cooler and removed the core to find this mess (see pic). The core was destroyed and possibly, probably (?) leaking and if so, the engine was ingesting it.  I bought and installed a new unit from Seaboard.  Engine runs fine now, all temps and pressures match the good port engine. BUT, the starboard engine now burns oil, at least a quart every five hours.  I will do a compression test shortly but what is the best guess, did the leaking after cooler destroy the piston rings?  Probably dreaming here but is there a chance this improves over time (by burning or washing out some form of corrosion)?    

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[dave carey]

Tony first off, thanks a for responding, and doing so, so quickly.  And yes, from the looks of the aftercooler core, this has been going on for a long time.

The boat is a 2005.  I bought it in 2017 and had the after coolers serviced at purchase by Cape Cod Marine (a certified Cummins shop).  I saw the service work in process, disassembled, cleaned, plenty of the recommended grease.  Around three years ago, I serviced them myself using the same procedure (and watching Seaboard video) and I pressure tested them for leaks.  Needless to say, that was not frequent enough and every two years is probably necessary.

After discovering the problem and buying the new core from Seaboard, I had the core/housing assembled, pressure tested and installed by WW Williams of South Carolina.  I drove from South Carolina to North Carolina and confirmed the oil loss/burning.

I had the oil changed just before I discovered this (three weeks ago) and the oil had no cream. Since then I have been looking at the dip stick and in the valve cover through the oil fill and do not see any cream.  I can remove the cover and do a better check.  I will pull and service the port after cooler asap.

I don’t see any smoke when underway but I do see oil sheen spotting in the exhaust water when idling.  Is there any other likely explanation for oil loss other than burning cause by ring damage?

Dave

 

 

 

 

[Tony Athens]

Obviously your aftercoolers have never been properly serviced.. I guess my past 25+ years of preaching this over internet has not helped you or the past owner..

 

Let’s move past that ASAP and do this NOW. Do what you have to do to bypass the seawater around the aftercooler for now   so you can RUN the engine. Do not worry about turbo air hoses, etc. for now.. We want to save you engines cylinders..  Check your oil for “creamy stuff” ( under your valve covers too) if the oil is OK start your engine and putt abound the harbor for an hour or so until the thermostat opens / engine is up to temp… If not OK, it’s multiple oil change time……………………..Do that every couple of days or so until BOTH aftercoolers are repaired, replaced etc etc..   

 

What I see did not happen in the last week–This  “salt water breach”  has been going on for months   What’s the vessels  proper maintenance history as you know it?    

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