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Smoke upon startup

Discussion in 'Technical Discussion' started by Dusty, May 2, 2005.

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  1. Dusty

    Dusty New Member

    Joined:
    May 2, 2005
    Messages:
    4
    Location:
    New Jersey
    Have Detroit 450's and I have noticed upon a cold start they smoke but when I put them in gear they stop smoking. They don't use oil but the port engine never runs over 165 degrees. I changed the thermostat but never made a difference.

    Why do these engines smoke? Thanks
  2. sford

    sford New Member

    Joined:
    Apr 1, 2004
    Messages:
    18
    Location:
    Grand Rapids, Mi
    It is the nature of the "Beast"!!!! These things especially on COLD starts smoke to beat the band!! It should go away once the reach operating temp... I assume you do not have block heaters and I have found that I have alomst completely eliminated the smoking at start by installing them...


    Steve
  3. DieselJoe

    DieselJoe New Member

    Joined:
    Feb 15, 2005
    Messages:
    5
    Location:
    ft lauderdale, fl

    First off, all Detroits do not smoke alot, only the ones that have some type of problem or the DDEC engines. DDEC's smoke alot because the compression is much lower then the mechanical diesels.


    How many hours are on the engines? Did they just start smoking or has the smoke become excessive over time? Is the smoke white, gray or blue?

    If the engines are old or high hours the most likely cause would be due to low cylinder compression. If the smoke never goes away until the engine is hot or put under load, then thats one possible cause. Most of the 71's smoke during the cold-start but should clear up after a few seconds if they are in good working order. Another possible cause would be faulty injector(s) If it was my boat I would have the injectors pop tested then a cylinder compression test to help determine the cause for abnormal start-up smoke. BTW,the cylinder compression should be min 425 PSI. New cylinders produce up to 475 PSI.

    DJ