What can cause diesel to be overloaded intermittently?

Discussion in 'Diesel Engines' started by Northeaster, Sep 15, 2018.

  1. BlueBell
    Joined: May 2017
    Posts: 678
    Likes: 64, Points: 28
    Location: Victoria BC Canada

    BlueBell Ahhhhh...

    You've changed so many things it could be anything!
    Or, worse yet, a combination of things.
    I think you need some on-sight help.
    Someone who knows what's going on and is a good troubleshooter.
    I don't envy you.
    Good luck with the painting.
     
  2. Northeaster
    Joined: Sep 2011
    Posts: 259
    Likes: 8, Points: 18, Legacy Rep: 45
    Location: Eastern Canada

    Northeaster Senior Member

    Bluebell - did you watch the video on the last page? What is it that strikes you as alarming or requiring such concern? I appreciate the replies but I do think that we're blowing this a bit out of proportion. We know that my diesel is overloaded by having too much weight So for the next few outings, I will not push the throttle too much. As I am almost done adding weight to the boat it is now really a matter of working with my propeller guy to remove possibly one or two inches of pitch or whatever is required to be able to achieve maximum RPMs under load, once the end weight is known.
    The purpose for me starting this post was to see if I had missed possible causes of intermittent overloading. But, as my fuel system was new with little use, air filter good, prop and bottom clean etc I think that it seems a matter of being overpropped enough that any added weight or adverse wind and seas reduce my rpms and therefore available hp, thus causing lower achievable speed. If I reduce pitch to the point where I can hit 2800rpms,with people on board and towing a dinghy, I think my overloading issues will be gone. Stupid of me to add pitch last time but we make mistakes sometimes.
     
  3. BlueBell
    Joined: May 2017
    Posts: 678
    Likes: 64, Points: 28
    Location: Victoria BC Canada

    BlueBell Ahhhhh...

    Yes, I watched the video.

    What makes you think I am alarmed or overly concerned?

    So, it runs fine for half an hour and then overloads.
    Weird.
    Strange, odd, even ridiculous, but if your not concerned, then don't worry about it.

    I guess to respond more correctly to your post: I have no idea why.
    Maybe just focus on your painting.
     
  4. Northeaster
    Joined: Sep 2011
    Posts: 259
    Likes: 8, Points: 18, Legacy Rep: 45
    Location: Eastern Canada

    Northeaster Senior Member

    Update - I had 2" of pitch taken off the prop during the winter. Had the boat out briefly when I put it in a couple of weeks ago (haven't been able to get out since).
    With the pitch taken off the prop, I am now able to get 3000rpm WOT (max intermittent rpm for the engine is 2800rpms which delivers 150hp).
    This was by myself, but with new aluminum floors in (replacing somewhat waterlogged temporary OSB / ply floors), but most gear aboard like anchors, full tanks, etc.

    So, I think i am good for now- engine should not be overloaded this year... Even with a couple families on board and beach gear, I should still hopefully be able to hit perhaps 2500rpm or so (which is max continuous rpms).
    I may end up building a small cabin some day...but that could be a year or two, or never... if i add more weight then, i may have to de-pitch again but at least for now I wont kill the diesel prematurely..
    thanks all for the input!
     
  5. Lepke
    Joined: Sep 2015
    Posts: 78
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    Location: Oregon to Alaska

    Lepke Junior Member

    An overtaking following sea is trying to turn your props backwards. Depending on your draft, wave height, and overtaking speed of wave will load and unload the engines.
     
  6. Northeaster
    Joined: Sep 2011
    Posts: 259
    Likes: 8, Points: 18, Legacy Rep: 45
    Location: Eastern Canada

    Northeaster Senior Member

    Thanks for the info Lepke- i had not heard that before - and with the engine already at the point of overloaded, due to overpropping, I would guess that might be more dramatic than if the engines had plenty of reserve torque and hp... now that it is not overpropped, I will see if the intermittent rpm drops subsides ..
     

  7. Magnus W
    Joined: Nov 2017
    Posts: 112
    Likes: 4, Points: 18
    Location: Sweden

    Magnus W Senior Member

    Your maximum rpm is 2800 so I assume it shouldn’t rev much past that unloaded as the governor would prevent it, perhaps 3000 rpm?

    You said earlier that you could reach 3300 rpm. Are you certain that the tach is accurate?
     
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