Silicon in engine oil

[Rene Dupuis]

Cummins 6 CTA 8.3 450hp
When I was in the process of purchasing this boat with twins it had 350 hours.I had the oil sample taken and the test results fine.
After purchase I changeed the oil & filters using Rotella 15/40 and stored the boat for the winter.
In the spring I added ,Seaboards Air sep system to both engins.
Ran the boat about 175 hours and had the oil sampled before changing it.
The samle came back with a critical reading for silicon in both engines.
The only thing different for the first 175 hours I put on the boat was, I added the new air sep system.
I decided that this new air cleaner system for some reason has caused this silicon issue.
Being consurned I removed the air seps and returned the Cummins original air-filters.
OK, with fresh Rotella oil & filters, I now run the boat for another 175 hours and again samle the oil. Again the results silicon in both engine but this time at a bit less.
What could be causing this silicon and how to correct this problem?
Please help.

Topic

[Rob Schepis]

Was the pre-purchase oil sample and the recent ones taken by the same person using the same sampling methods and the same apparatus?

[Tony Athens]

With so few hours on the engines overall, no real trend over time, personally I would totally ignore the samples..

What you really need to do tell me about the last time the aftercoolers were removed from the engines, put on the bench and serviced per my protocol?

Also–

Engine serial numbers?

Saltwater or fresh water vessel

Exact oil filter you are using?

WOT engine RPM’s loaded as you use the vessel?

What is you happy cruise RPM & vessel speed?

I’d like to see good pictures of the engines as installed in the vessel

Tony

[Author]

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