QSB 5.9 Oil Analysis

[dave carey]

I have a boat with twin QSB 5.9s. They are vintage 2004 and I have 1,100 hours on both. I have owned the boat for four years and have done oil analysis for the last two years. The results of both analysis show high aluminum (~100 ppm) content. The engines run very well, seem to match design numbers for rpm, fuel consumption, etc. and generate no apparent smoke.

Any one know if there is an issues with these engines or any other possible explanation? Is the most likely source the aluminum pistons (the oil pan is steel). Would lack of runtime be a possible cause (90 hours per year average but oil changed every year)? Thanks.

Topic

[dave carey]

Thanks Tony!

Tony,

Thanks for the information, now I understand. I want to add: you and the team at Seaboard are astounding, I’ve never encountered folks with so much marine diesel knowledge.

Thanks!

Dave

[Rob Schepis]

I have the original 2001 vintage aftercoolers with the aluminum finned core. It’s seen sbmar servicing every 3 or so years and spent entire life in brackish water. Visually they and the housings look good for their age. Just did oil samples in November 2019 and all was normal. Did your fins or housings show corrosion damage?

[Tony Athens]

Only a trend over 100’s of hours of use can offer any value as to internal engine wear.. A random sample has no real value unless something about the engine when running was obviously wrong and sampling the oil was a last resort after all the other avenues of diagnoses were accomplished. I am still waiting to find an engine that failed because the oil was never sampled.. But I see them fail all the time even though the oil was sampled during a survey at the time of sale.

IMO, 90++ % of all survey miss the things that take out marine engines Exhaust design, internal aftercooler condition, and proper loading of the engine in the cruise RPM mode……But, that’s a big reason my crew stays busy.

Your “aluminum” is from your aftercooler. Your engine vintage suggests you have an aluminum finned unit made by MOEN in the late 90 thru about 2003-ish.. Rob Schepis knows them well.

Next time you service it, take some really good pics

[dave carey]

Aftercoolers

Hi Tony,

I bought the boat in 2016, the aftercoolers had never been serviced. I serviced them right away and I am servicing them again this year (plan to do it every four years). So maybe aluminum molecules are getting blown into the combustion chamber from the aftercoolers?

Curious, why is oil analysis of no value?

Thanks!

[Tony Athens]

Oil analysis is of no value & is meaningless..

Try “aluminum molecules” from the aftercoolers housings and fins..

When was the last time you put them on the bench and serviced them per my protocol?

Tony

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