Blowby test results 14 H20 Excessive? (12 Worn)

[Heather Pumphrey]

Recently sea trialed a 2006 44 Sea Ray Sundancer with QSC 8.3 500’s with 1000 hours. The results for the blow by were 11.3 and 14.2. We do not know the maintenance history on the engines and know that the heat exchanges, aftercoolers & valve adjustments need to be serviced – this has not been done at least in the last 3 years and 300 hours. The oil samples came back good but not a lot of history. There was no noticeable smoke coming from the engines. The starboard turbo has a heavy exhaust leak with excessive soot and needs to be replaced. There was also wobbling from that engine – mounts were checked and in good condition. Also, note that the day of the sea trial the conditions were rough with 4 to 5′ chops.

Questions:
Is the 14.2 reading excessively high and worrisome?
Should we do another blow by test to rule out major engine issues once the turbo is replaced?
Would the wobbling be caused by the failing turbo waste gate?

Sea trial and oil sample results links.

Topic

[Heather Pumphrey]

Dave,

Thanks so much as this is very helpful and reassuring!

They did use the correct .302 orifice according to the Cummins specs.

Heather

[Dave Carlson]

I ran into this problem on the same engines two years ago as a seller and it almost cost me a sale. My boat had 750 hrs, cold start was good and they did not use oil but the engine surveyor said 14 was too high. He was not a Cummins mechanic. I contacted 2 Cummins dealers and was told 14 is the high end of Cummins specs and QSC’s run higher than mechanical engines.

I purchased another QSC powered boat after this sale and the blow by tests were around 13. The engines were perfect. I did learn during this experience there is a specific size orifice the tec needs to use which can change the results if the wrong one is used but I don’t remember the correct size.

Good luck with your decision.

[Author]

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