Cummins Marine Diesel Repower Specialists › Forums › Cummins Marine Engines › 2004 Cummins 6CTA 8.3 Oil Analysis 635 hours

  • This topic has 9 replies, 3 voices, and was last updated 4 years ago by JJM.
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  • October 18, 2019 at 6:16 pm #79494

    JJM
    Participant
    Engines: Cummins 480 CE
    Location: CT
    Country: United States

    Hey Guys ,

    New to the forum but not to the automotive/marine industry. I am in the process of purchasing a boat with these Engines in it and Kubota Generator. The oil samples taken did not come back to be the best however this is some discrepancy on wether its just because its old oil and the motors were started multiple times over the last few months and not warmed up completely. So all those dry starts…….I am alittle concerned with the motor results but more with the generator results. Can you take a look and let me know your thoughts. To me it appears the dry starts just left some good wear with the Iron and some chromium. Generator on other hand not sure what to make of that. The broker just had all the fluids changed after this incident and is going to try and get 8-10 hours on the engines and 20 hours on generator and retest to see how we do. Thoughts?

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  • October 24, 2019 at 4:29 am #79788

    JJM
    Participant
    Engines: Cummins 480 CE
    Location: CT
    Country: United States

    Thanks Steve. Yes it was burning about 26.8 combined at about 2100 rpms also

    October 24, 2019 at 3:33 am #79786

    Steve Lewis
    Participant
    Vessel Name: Just Us
    Engines: Cummins 480CE
    Location: Marblehead, OH
    Country: USA

    Thoughts…….

    on #2 and the WOT Fuel burn………

    Do you run your boat at WOT 100% of the time? I hope not. So the relevant fuel burn numbers will be those in the 1800 – 2400 RPM Range. Some where in that range is going to be your cruise RPM where you will operate your boat most of the time. That is where you need to get the fuel burn to be ON OR BELOW the 450 curve. Which is why I mentioned 13.6 gph at 2200 rpm in your other post. You may recall that in your other post, Rob realized that these engines are 480CE’s so they have electronic fuel flow measuring so you can get a good idea of fuel flow at any RPM and therefore need to focus on Cruise RPM fuel burn not WOT Fuel Burn. Re-Read the following and focus very carefully on the conclusion of the article.

    Propping the Cummins 6CTA 8.3 480CE vs. 430/450 Diamond Engine

    Conclusion of the Article……….
    “Hereā€™s the bottom line: If you cannot get your load close to the 450 Diamonds curve and be happy with the performance, then you have what we call, ā€œtoo much boat and not enough engineā€ And lastly, think about where all of the wear and tear takes place on these engine ā€“ Itā€™s not at WOT, itā€™s at CRUISE!”

    So it is a good idea to get a full graph of the entire RPM range and then plot it against the 450 curve. The whole curve not just the top end of the curve.

    October 23, 2019 at 5:39 pm #79777

    JJM
    Participant
    Engines: Cummins 480 CE
    Location: CT
    Country: United States

    New Information

    So I have some new and good information as things progress here.

    1) I had a analytical Ferrogram performed on one of the motor samples. The concensus was that the high iron content was mostly rust that was just from cylinder wall rust because the boat sat for several weeks or a month before between starting cycles. The copper was mostly all leaching from the oil cooler with only one actual visible piece. So all in all it came back with a #2 which meant no action needed except flush fluids and retest at 60-80 hours. So that is positive.

    2) All fluids were flushed out and changed on the boat, new fuel filled up in the tanks, new fuel filters and now the broker is going to put some hours on it for retesting. Thus far with full tanks, head wind boat was able to reach 2680 rpms on both motors without issue. The fuel burn was 45.96 gph at WOT which is spot on for the 450 Curve . So it appears motors are running strong and within spec thus far. Speed was only 26 knots but that was with a head wind and against the tide. Hoping to see 28 knots in ideal conditions.

    Thoughts?

    October 21, 2019 at 5:51 am #79623

    JJM
    Participant
    Engines: Cummins 480 CE
    Location: CT
    Country: United States
    Rob Schepis wrote:

    I would imagine if engines can hit the governor , have proper boost pressures and temps then the likely hood is they are ok and do not have low compression. Am I thinking right?

    Rob,

    Do I have the right frame of mind when I said

    “I would imagine if engines can hit the governor , have proper boost pressures and temps then the likely hood is they are ok and do not have low compression. Am I thinking right?”

    Would you agree ok to proceed with this boat if all of the above are within spec?

    October 20, 2019 at 5:56 pm #79605

    Rob Schepis
    Forum Moderator
    Vessel Name: Tenacious
    Engines: 6BTA 5.9 330's - "Seaboard Style"
    Location: Long Island, NY
    Country: USA

    Yes at startup, especially in colder weather. Underway once up to temperature you may see some under hard acceleration and pushing her over the hump

    1 user thanked author for this post.
    JJM
    October 20, 2019 at 6:43 am #79578

    JJM
    Participant
    Engines: Cummins 480 CE
    Location: CT
    Country: United States
    Rob Schepis wrote:

    Youā€™ll want a good cold start (good time of year in CT for that) and to look for any signs of smoke and itā€™s color at startup and underway.

    Wouldn’t it be considered normal for the boat to smoke at idle when first started cold? Underway I would also expect to see alittle no?

    October 19, 2019 at 5:42 am #79522

    Rob Schepis
    Forum Moderator
    Vessel Name: Tenacious
    Engines: 6BTA 5.9 330's - "Seaboard Style"
    Location: Long Island, NY
    Country: USA

    Youā€™ll want a good cold start (good time of year in CT for that) and to look for any signs of smoke and itā€™s color at startup and underway.

    1 user thanked author for this post.
    JJM
    October 19, 2019 at 5:30 am #79519

    JJM
    Participant
    Engines: Cummins 480 CE
    Location: CT
    Country: United States

    Alright. Unfortunately I have the survey and sea trial coming up and need to make my best guess at wether they are functioning properly or I have a big bill coming up. I would imagine if engines can hit the governor , have proper boost pressures and temps then the likely hood is they are ok and do not have low compression. Am I thinking right?

    October 19, 2019 at 4:03 am #79516

    Rob Schepis
    Forum Moderator
    Vessel Name: Tenacious
    Engines: 6BTA 5.9 330's - "Seaboard Style"
    Location: Long Island, NY
    Country: USA

    I would put the engines and genny through numerous hours of normal proper use cycles before paying too much attention to the reports. Long periods of sitting and idling engines at the dock are not good and are not “normal”

    1 user thanked author for this post.
    Tony Athens
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